Fair Value Disclosures [Abstract] Financial Instruments Measured at Fair Value on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Changes in Fair Value Included in Consolidated Statements of Income Changes In Fair Value Included In Consolidated Statements Of Income [Text Block] Changes In Fair Value Included In Consolidated Statements Of Income [Text Block] Changes in Level 3 Fair Value Measurements Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Assets and Liabilities Measured at Fair Value on Non-Recurring Basis Fair Value Measurements, Nonrecurring [Table Text Block] Carrying and Estimated Fair Values of Financial Instruments Carried on Balance Sheet Fair Value, by Balance Sheet Grouping [Table Text Block] Fair Value Accounting Fair Value Disclosures [Text Block] Loans and Allowance for Loan Losses [Abstract] Loans and Allowance for Loan Losses [Abstract] Schedule of Financing Receivables Past Due [Table] Schedule of Financing Receivables Past Due [Table] Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Domain] Total commercial and industrial Commercial And Industrial [Member] Commercial and Industrial [Member] Total commercial real estate Commercial Real Estate [Member] Total consumer Retail [Member] Financing Receivable, Recorded Investment, by Class of Financing Receivable [Axis] Class of Financing Receivable, Type [Axis] Class of Financing Receivable [Domain] Class of Financing Receivable, Type [Domain] Commercial, financial, and agricultural Commercial, Financial and Agricultural [Member] Commercial, Financial and Agricultural [Member] Owner-occupied Owner-Occupied [Member] Owner-Occupied [Member] Investment properties Investment Properties [Member] Investment Properties [Member] 1-4 family properties One To Four Family Properties [Member] One To Four Family Properties [Member] Land and development Land Acquisition [Member] Land Acquisition [Member] Consumer mortgages Consumer Loan [Member] Home equity lines Home Equity Line of Credit [Member] Credit cards Credit Card Receivable [Member] Other consumer loans Other Consumer Loans [Member] Other Consumer Loans [Member] Financing Receivable, Recorded Investment, Past Due [Line Items] Financing Receivable, Recorded Investment, Past Due [Line Items] Total commercial and industrial Loans Receivable, Gross, Commercial and Industrial Total commercial real estate Loans Receivable, Gross, Commercial, Real Estate Total consumer Loans and Leases Receivable, before Fees, Gross Total loans Loans and Leases Receivable, Gross Deferred fees and costs, net Loans and Leases Receivable, Deferred Income Total loans, net of deferred fees and costs Loans and Leases Receivable, Net of Deferred Income Earnings Per Share [Abstract] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock Common Stock [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum Maximum [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Maximum repurchase amount (in shares) Stock Repurchase Program, Number of Shares Authorized to be Repurchased Exercise price (in dollars per share) Share Price Potentially dilutive shares Weighted Average Number Diluted Shares Outstanding Adjustment Other Assets [Abstract] Other Assets Other Assets Disclosure [Text Block] Investments [Abstract] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] U.S. Treasury securities US Treasury Securities [Member] U.S. Government agency securities US Government Agencies Debt Securities [Member] Mortgage-backed securities issued by U.S. Government agencies Mortgage Backed Securities Issued By U S Government Agencies [Member] Mortgage Backed Securities Issued By U S Government Agencies [Member] Mortgage-backed securities issued by U.S. Government sponsored enterprises Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises Collateralized Mortgage Obligations Issued By U S Government Sponsored Agencies or Sponsored Enterprises [Member] Collateralized Mortgage Obligations Issued By U S Government Sponsored Agencies or Sponsored Enterprises [Member] Commercial mortgage-backed securities issued by U.S. Government sponsored enterprises Commercial mortgage-backed securities issued by U.S. Government sponsored agencies [Member] Commercial mortgage-backed securities issued by U.S. Government sponsored agencies [Member] State and municipal securities US States and Political Subdivisions Debt Securities [Member] Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Amortized Cost, Within One year Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost Amortized Cost, 1 to 5 Years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost Amortized Cost, 5 to 10 Years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost Amortized Cost, More Than 10 years Debt Securities, Available-for-sale, Allocated and Single Maturity Date, Maturity, after 10 Years, Amortized Cost Total Amortized Cost Debt Securities, Available-for-sale, Amortized Cost Fair Value, Within One year Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value Fair Value, 1 to 5 Years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value Fair Value, 5 to 10 Years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value Fair Value, More Than 10 years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after 10 Years, Fair Value Total Fair Value Debt Securities, Available-for-sale Schedule of Impaired Financing Receivable [Table] Schedule of Impaired Financing Receivable [Table] Collateral [Axis] Collateral [Axis] Collateral [Domain] Collateral [Domain] Collateral Pledged Collateral Pledged [Member] Financing Receivable, Impaired [Line Items] Financing Receivable, Impaired [Line Items] Pledged to secure deposits Debt Securities, Available-for-sale, Restricted Securities in a loss position for less than twelve months Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year Securities in a loss position for more than twelve months Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year Interest-bearing Deposit Liabilities [Abstract] Interest-bearing demand deposits Interest-bearing Domestic Deposit, Demand Money market accounts, excluding brokered deposits Deposits, Money Market Deposits Savings accounts Deposits, Savings Deposits Time deposits, excluding brokered deposits Time Deposits, Excluding Brokered Deposits Time Deposits, Excluding Brokered Deposits Brokered deposits Interest-bearing Domestic Deposit, Brokered Total interest-bearing deposits Interest-Bearing Deposit Liabilities And Time Deposits Interest-Bearing Deposit Liabilities And Time Deposits Aggregate amount of time deposits of $250,000 or more Time Deposits, $250,000 or More Time Deposits, $250,000 or More Time Deposits, by Maturity [Abstract] Time Deposits, Fiscal Year Maturity [Abstract] Maturing within one year Time Deposit Maturities, Next Twelve Months Between 1 - 2 years Time Deposits, Maturing in Year One and Two Time Deposits, Maturing in Year One and Two 2 - 3 years Time Deposits, Maturing in Years Two and Three Time Deposits, Maturing in Years Two and Three 3 - 4 years Time Deposits, Maturing in Years Three and Four Time Deposits, Maturing in Years Three and Four 4 - 5 years Time Deposits, Maturing in Years Four and Five Time Deposits, Maturing in Years Four and Five Thereafter Time Deposits, Maturing in After Five Years Time Deposits, Maturing in After Five Years Time deposits Time Deposits Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Quarterly Financial Data [Abstract] Summary of Quarterly Financial Data (Unaudited) Quarterly Financial Information [Text Block] Subsequent Events [Abstract] Subsequent Event [Table] Subsequent Event [Table] Minimum Minimum [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] FCB Financial Holdings, Inc. FCB Financial Holdings, Inc. [Member] FCB Financial Holdings, Inc. [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] 5.9% Subordinated Notes Five Point Nine Percent Subordinated Notes, Due 2029 [Member] Five Point Nine Percent Subordinated Notes, Due 2029 [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Consideration transferred Business Combination, Consideration Transferred Loans, net Loans and Leases Receivable, Net Amount Deposits Deposits Number of branches Number of Branches Number of Branches Merger-related expense Business Combination, Acquisition Related Costs Issuance of common stock Stock Issued During Period, Shares, Acquisitions Cash paid Payments to Acquire Businesses, Gross Pro forma total revenue, net of interest expense Business Acquisition, Pro Forma Revenue Pro forma net income available to common shareholders Business Acquisition, Pro Forma Net Income (Loss) Debt, face amount Debt Instrument, Face Amount Stated percentage Debt Instrument, Interest Rate, Stated Percentage Interest rate during the year Debt Instrument, Interest Rate During Period Share-based Compensation [Abstract] Schedule of Stock Options Activity Share-based Compensation, Stock Options, Activity [Table Text Block] Fair Value of Option Grants Used in Measuring Compensation Expense Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Schedule of Restricted Stock Units Activity Schedule of Nonvested Restricted Stock Units Activity [Table Text Block] Schedule of Grants Under All Synovus Equity Compensation Plans Schedule of Aggregate Information of Grants Under All Entity Equity Compensation Plans [Table Text Block] Schedule of Aggregate Information of Grants Under All Entity Equity Compensation Plans [Table Text Block] Employer matching contribution, percent Defined Contribution Plan, Employer Matching Contribution, Percent of Match 401(k) percent of match Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent Annual contribution Defined Contribution Plan, Cost Stock purchase plan, percent of match Defined Contribution Plan, Stock Purchase Plan, Percent of Mmatch Defined Contribution Plan, Stock Purchase Plan, Percent of Mmatch Stock purchase plans compensation expense Deferred Compensation Arrangement with Individual, Compensation Expense Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Allowance for Loan and Lease Losses [Roll Forward] Allowance for Loan and Lease Losses [Roll Forward] Beginning balance Loans and Leases Receivable, Allowance Charge-offs Allowance for Loan and Lease Losses, Write-offs Recoveries Allowance for Loan and Lease Loss, Recovery of Bad Debts Provision for loan losses Provision for Loan and Lease Losses Ending balance Ending balance: individually evaluated for impairment Financing Receivables, Allowance for Credit Losses, Individually Evaluated for Impairment Allowance for Credit Losses related to loans individually evaluated for impairment. Ending balance: collectively evaluated for impairment Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment Ending balance: individually evaluated for impairment Financing Receivable, Individually Evaluated for Impairment Ending balance: collectively evaluated for impairment Financing Receivable, Collectively Evaluated for Impairment Deferred fees and costs, net Purchased credit-impaired loans Purchased Credit-impaired Loans Purchased Credit-impaired Loans Allowance for purchased credit-impaired loans Allowance for Purchased Credit-impaired Loans Allowance for Purchased Credit-impaired Loans Commitments and Contingencies Disclosure [Abstract] Loss Contingencies [Table] Loss Contingencies [Table] Loss Contingencies by Nature of Contingency [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Guarantee Obligations [Member] Guarantee Obligations [Member] Letters of credit Standby and Commercial Letters of Credit [Member] Standby and Commercial Letters of Credit [Member] Commitments to fund commercial and industrial loans Commitments to Fund Commercial and Industrial Loans [Member] Commitments to Fund Commercial and Industrial Loans [Member] Commitments to fund commercial real estate, construction, and land development loans Commitments to Fund Commercial Real Estate, Construction, and Land Development Loans [Member] Commitments to Fund Commercial Real Estate, Construction, and Land Development Loans [Member] Commitments under home equity lines of credit Commitments under Home Equity Lines of Credit [Member] Commitments under Home Equity Lines of Credit [Member] Unused credit card lines Unused Credit Card Lines [Member] Unused Credit Card Lines [Member] Other loan commitments Other Loan Commitments [Member] Other Loan Commitments [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Total letters of credit and unfunded lending commitments Loss Contingency, Estimate of Possible Loss Carrying amount included in other assets Affordable Housing Program Obligation Amount of future funding commitments included in carrying amount Affordable Housing Program Obligation, Future Funding Included in Carrying Amount Affordable Housing Program Obligation, Future Funding Included in Carrying Amount Short-term construction loans and letter of credit commitments Affordable Housing Program Obligation, Short-term Construction Loans and Letter of Credit Commitments Affordable Housing Program Obligation, Short-term Construction Loans and Letter of Credit Commitments Funded portion of short-term loans and letters of credit Affordable Housing Program Obligation, Funded Portion of Short-term Loans and Letters of Credit Affordable Housing Program Obligation, Funded Portion of Short-term Loans and Letters of Credit Contractual amount net of risk participations Contractual Amount Net of Risk Participations Contractual Amount Net of Risk Participations Guarantor obligations, monetary amount Guarantor Obligations, Liquidation Proceeds, Monetary Amount Guarantor obligations, advanced payment to merchant Guarantor Obligations, Advanced Payment to Merchant Guarantor Obligations, Advanced Payment to Merchant Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Parent Company Parent Company [Member] Legal Entity [Axis] Entity [Domain] Synovus Bank Reporting Unit Synovus Bank [Member] Synovus Bank [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Senior Notes Senior Notes [Member] FHLB Advances Federal Home Loan Bank Advances [Member] Other Notes Payable and Capital Leases Other Notes Payable and Capital Leases [Member] Other Notes Payable and Capital Leases [Member] 3.125% Senior Notes due November 1, 2022 Three Point One Two Five Percent Senior Notes, Due November 1, 2022 [Member] Three Point One Two Five Percent Senior Notes, Due November 1, 2022 [Member] 5.75% Subordinated Notes, due December 15, 2025 Five Point Seven Five Percent Subordinated Notes, Due December 15, 2025 [Member] Five Point Seven Five Percent Subordinated Notes, Due December 15, 2025 [Member] LIBOR 1.80% debentures, due April 19, 2035 LIBOR Plus 180 Debentures, due April 19, 2035 [Member] LIBOR Plus 180 Debentures, due April 19, 2035 [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] LIBOR London Interbank Offered Rate (LIBOR) [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Long-term debt Long-term Debt, Gross Subordinated notes Subordinated Debt Unsecured debt Unsecured Debt FHLB advances with interest and principal payments due at various maturity dates through 2018 Long-term Federal Home Loan Bank Advances Other notes payable and capital leases with interest and principal payments due at various maturity dates through 2031 Other Notes Payable and Capital Lease Obligations Other Notes Payable and Capital Lease Obligations Long-term debt Long-term Debt Basis spread on variable rate Debt Instrument, Basis Spread on Variable Rate Interest rate at period end Debt Instrument, Interest Rate, Effective Percentage Weighted average interest rate Long-term Debt, Weighted Average Interest Rate, at Point in Time Stockholders' Equity Note [Abstract] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Net Unrealized Gains (Losses) on Cash Flow Hedges Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Net Unrealized Gains (Losses) on Investment Securities Available for Sale Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] Post-Retirement Unfunded Health Benefit Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Changes in Accumulated Other Comprehensive Income (Loss) by Component [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Beginning balance Stockholders' Equity Attributable to Parent Other comprehensive (loss) income before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Amounts reclassified from accumulated other comprehensive income (loss) Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Net current period other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Reclassification from adoption of ASU 2018-02 Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Securities, After Tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Securities, After Tax Cumulative-effect adjustment from adoption of ASU 2016-01 Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Investment Transferred from Available-for-sale to Other Assets, after Tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Investment Transferred from Available-for-sale to Other Assets, after Tax Ending balance Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Land Land [Member] Buildings and improvements Building and Building Improvements [Member] Leasehold improvements Leasehold Improvements [Member] Furniture and equipment Furniture and Fixtures [Member] Construction in progress Construction in Progress [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Total premises and equipment Property, Plant and Equipment, Gross Less: Accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Premises and equipment, net Property, Plant and Equipment, Net Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] State State and Local Jurisdiction [Member] Type of Tax Credits Carryforward [Axis] Type of Tax Credits Carryforward [Axis] Type of Tax Credits Carryforward [Axis] Type of Tax Credits Carryforward [Domain] Type of Tax Credits Carryforward [Domain] [Domain] for Type of Tax Credits Carryforward [Axis] Net Operating Loss Net Operating Loss Tax Credits Carryforward [Member] Net Operating Loss Tax Credits Carryforward [Member] Other Credits Other Tax Credits Carryforward [Member] Other Credits [Member] Carryforwards Expiration [Axis] Carryforwards Expiration [Axis] Carryforwards Expiration [Axis] Carryforwards Expiration [Domain] Carryforwards Expiration [Domain] Carryforwards Expiration [Domain] 2023-2027 Tax Carryforwards Expiration, Period One [Member] Tax Carryforwards Expiration, Period One [Member] 2028-2032 Tax Carryforwards Expiration, Period Two [Member] Tax Carryforwards Expiration, Period Two [Member] 2033-2036 Tax Carryforwards Expiration, Period Three [Member] Tax Carryforwards Expiration, Period Three [Member] 2019-2023 Tax Carryforwards Expiration, Period Four [Member] Tax Carryforwards Expiration, Period Four [Member] 2024-2028 Tax Carryforwards Expiration, Period Five [Member] Tax Carryforwards Expiration, Period Five [Member] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Deferred Tax Asset Balance Deferred Tax Assets, Gross Valuation Allowance Deferred Tax Assets, Valuation Allowance Total deferred tax assets Deferred Tax Assets, Net of Valuation Allowance Pre-Tax Earnings Necessary to Realize Deferred Tax Assets, Pre-Tax Earnings Necessary to Realize Deferred Tax Assets, Pre-Tax Earnings Necessary to Realize Business Combinations [Abstract] Acquisition Business Combination Disclosure [Text Block] Loans Outstanding by Classification Loans Outstanding By Classification Table Text Block Loans Outstanding By Classification Schedule of Current, Accruing Past Due, and Nonaccrual Loans Schedule of Financing Receivables, Non Accrual Status [Table Text Block] Loan Portfolio Credit Exposure Loan Portfolio Credit Exposure [Table Text Block] Loan Portfolio Credit Exposure [Table Text Block] Schedule of Allowances for Loan Losses and Recorded Investment in Loans Allowance for Credit Losses [Text Block] Schedule of Impaired Loans Impaired Financing Receivables [Table Text Block] Troubled Debt Restructurings Troubled Debt Restructurings on Financing Receivables [Table Text Block] Fair Value, By Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Fair Value by Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring Fair Value, Measurements, Recurring [Member] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Collateralized mortgage obligations issued by U.S. Government sponsored agencies or enterprises Collateralized Mortgage Obligations Issued By U S Government Sponsored Agencies or Enterprises [Member] Collateralized Mortgage Obligations Issued By U S Government Sponsored Agencies or Enterprises [Member] Other investments Other Investments [Member] Financial Instruments [Domain] Corporate debt and other debt securities Corporate Debt and Other Debt Securities [Member] Corporate Debt and Other Debt Securities [Member] Mutual funds Mutual Fund [Member] Interest rate contracts Interest Rate Contract [Member] Mortgage derivatives Mortgage Derivatives [Member] Mortgage Derivatives [Member] Visa derivative Visa Derivative [Member] Visa Derivative [Member] Liability Class [Axis] Liability Class [Axis] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Visa derivative Other Derivative Liability Contracts [Member] Other Derivative Liability Contract [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Level 1 Fair Value, Inputs, Level 1 [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Level 3 Fair Value, Inputs, Level 3 [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Trading securities Debt Securities, Trading, and Equity Securities, FV-NI Mortgage loans held for sale Mortgages Held-for-sale, Fair Value Disclosure Total investment securities available for sale Private equity investments Private Equity Investments Private Equity Investments Equity Securities, FV-NI Equity Securities, FV-NI Mutual funds held in rabbi trusts Mutual Funds Held In Rabbi Trusts Mutual funds held In Rabbi Trusts. GGL/SBA loans servicing asset Servicing Asset at Fair Value, Amount Derivative asset positions Derivative Asset Trading account liabilities Trading Liabilities, Fair Value Disclosure Earnout liability Earnout Liabilities, Fair Value Disclosure Earnout Liabilities, Fair Value Disclosure Derivative liabilities Derivative Liability Gain (loss) included in earnings Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Investment Securities Available for Sale Available-for-sale Securities [Member] Private Equity Investments Private Equity Funds [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] GGL/SBA Loans Servicing Asset SBA/GGL Servicing Asset [Member] SBA /GGL Servicing Asset [Member] Earnout Liability Other Liabilities [Member] Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Beginning balance, January 1, Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs Included in earnings Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings Unrealized (losses) gains included in other comprehensive income Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Other Comprehensive Income (Loss) Additions Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Additions Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Additions Sales Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Sales Settlements Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements Transfer from amortization method to fair value Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers, Net Measurement period adjustments related to Global One acquisition Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Period Increase (Decrease) Ending balance, December 31, Total net (losses) for the year included in earnings attributable to the change in unrealized gains (losses) relating to assets and liabilities still held at December 31, Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Period Increase (Decrease), Included in Earnings Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Period Increase (Decrease), Included in Earnings Schedule of Interest Bearing Deposits Schedule of Interest Bearing Deposits [Table Text Block] Schedule of Interest Bearing Deposits [Table Text Block] Schedule of Cash Maturities of Time Deposits Schedule of Cash Maturities of Time Deposits [Table Text Block] Schedule of Cash Maturities of Time Deposits [Table Text Block] Share-based Compensation and Other Employment Benefit Plans Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Goodwill [Table] Schedule of Goodwill [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Trust Services Reporting Unit Trust Services [Member] Trust Services [Member] Global One Global One [Member] Global One [Member] Goodwill [Line Items] Goodwill [Line Items] Goodwill Goodwill Number of reporting units Number of Reporting Units Accumulated amortization Amortization of Intangible Assets Aggregate estimated amortization expense in 2019 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months Aggregate estimated amortization expense in 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Two Aggregate estimated amortization expense in 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Three Aggregate estimated amortization expense in 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Four Aggregate estimated amortization expense in 2023 Finite-Lived Intangible Assets, Amortization Expense, Year Five Schedule of Financing Receivable, Troubled Debt Restructurings [Table] Schedule of Financing Receivable, Troubled Debt Restructurings [Table] Loan Restructuring Modification [Axis] Loan Restructuring Modification [Axis] Financing Receivable, Troubled Debt Restructurings [Domain] Loan Restructuring Modification [Domain] Below Market Interest Rate Interest Rate Below Market Reduction [Member] Other Concessions Term Extensions and or Other Concessions [Member] Term Extensions and/or Other Concessions [Member] Financing Receivable, Modifications [Line Items] Financing Receivable, Modifications [Line Items] Number of Contracts Financing Receivable, Modifications, Number of Contracts Total loans Financing Receivable, Modifications, Post-Modification Recorded Investment Write-down Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down Net Deferred Tax Assets Components of Deferred Tax Assets and Liabilities [Abstract] Deferred income tax assets Components of Deferred Tax Assets [Abstract] Allowance for loan losses Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Provision for Loan Losses Net operating loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards Net unrealized losses on investment securities available for sale Deferred Tax Assets, Unrealized Losses on Available-for-Sale Securities, Gross Employee benefits and deferred compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost Tax credit carryforwards Deferred Tax Assets, Tax Credit Carryforwards Deferred revenue Deferred Tax Assets, Deferred Income Lease rental Deferred Tax Assets, Lease Rentals Deferred Tax Assets, Lease Rentals Non-performing loan interest Deferred Tax Assets, Non-Performing Loan Interest Deferred Tax Assets, Non-Performing Loan Interest Other Deferred Tax Assets, Other Total gross deferred tax assets Less valuation allowance Deferred tax liabilities Components of Deferred Tax Liabilities [Abstract] Excess tax over financial statement depreciation Deferred Tax Liabilities, Depreciation Deferred Tax Liabilities, Depreciation Other properties held for sale Deferred Tax Liabilities, Fixed Assets Held-for-Sale Deferred Tax Liabilities, Fixed Assets Held-for-Sale Other Deferred Tax Liabilities, Other Total gross deferred income tax liabilities Deferred Tax Liabilities, Net Net deferred tax assets Deferred Tax Assets, Net Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Series C Preferred Stock Series C Preferred Stock [Member] Series D Preferred Stock Series D Preferred Stock [Member] Statement [Line Items] Statement [Line Items] ASSETS Assets [Abstract] Cash and due from banks Cash and Due from Banks Interest-bearing funds with Federal Reserve Bank Interest bearing funds with Federal Reserve Bank Interest bearing funds deposited with the Federal Reserve Bank. Interest earning deposits with banks Interest-bearing Deposits in Banks and Other Financial Institutions Federal funds sold and securities purchased under resale agreements Federal Funds Sold and Securities Purchased under Agreements to Resell Total cash, cash equivalents, restricted cash, and restricted cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Mortgage loans held for sale, at fair value Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Mortgage Investment securities available for sale, at fair value Available-for-sale Securities Loans, net of deferred fees and costs Allowance for loan losses Loans, net Cash surrender value of bank-owned life insurance Bank Owned Life Insurance Premises and equipment, net Other intangible assets Other Intangible Assets, Net Deferred tax asset, net Other assets Other Assets Total assets Assets LIABILITIES AND SHAREHOLDERS' EQUITY Liabilities and Equity [Abstract] Liabilities Liabilities [Abstract] Non-interest-bearing deposits Noninterest-bearing Deposit Liabilities Interest-bearing deposits Total deposits Federal funds purchased and securities sold under repurchase agreements Federal Funds Purchased And Other Short Term Borrowings Federal funds purchased, repurchase agreements, and other short-term borrowings Other short-term borrowings Other Short-term Borrowings Other liabilities Other Liabilities Total liabilities Liabilities Shareholders' Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Preferred Stock Preferred Stock, Value, Issued Common stock - $1.00 par value; authorized 342,857,143 shares; 143,300,449 issued at December 31, 2018 and 142,677,449 issued at December 31, 2017; 115,865,510 outstanding at December 31, 2018 and 118,897,295 outstanding at December 31, 2017 Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Treasury stock, at cost – 27,434,939 shares at December 31, 2018 and 23,780,154 shares at December 31, 2017 Treasury Stock, Value Accumulated other comprehensive loss, net Accumulated Other Comprehensive Income (Loss), Net of Tax Retained earnings Retained Earnings (Accumulated Deficit) Total shareholders’ equity Total liabilities and shareholders' equity Liabilities and Equity Schedule of Components of Income Tax Expense (Benefit) Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of Effective Income Tax Rate Reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of Net Operating Loss and Tax Credit Carryforward Schedule of Net Operating Loss and Tax Credit Carryforward [Table Text Block] Schedule of Net Operating Loss and Tax Credit Carryforward [Table Text Block] Reconciliation of Unrecognized Tax Benefits Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Revenue from Contract with Customer [Abstract] Non-interest Income Revenue from Contract with Customer [Text Block] Statement of Comprehensive Income [Abstract] Net income, Before-tax Amount Income (loss) before income taxes including income from discontinued operations before income taxes Income (loss) before income taxes including income from discontinued operations before income taxes Net income, Tax (Expense) Benefit Income Tax Expense (Benefit) Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net change related to cash flow hedges: Before-tax Amount Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax [Abstract] Reclassification adjustment for losses realized in net income, Before-tax Amount Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax Net change related to cash flow hedges: Tax (Expense) Benefit Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax [Abstract] Reclassification adjustment for losses realized in net income, Tax (Expense) Benefit Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax Net change related to cash flow hedges: Net of Tax Amount Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax [Abstract] Reclassification adjustment for losses realized in net income, Net of Tax Amount Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax Net unrealized (losses) gains on investment securities available for sale: Before-tax Amount Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Tax [Abstract] Reclassification adjustment for net losses (gains) realized in net income, Before-tax Amount Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax Net unrealized (losses) gains arising during the period, Before-tax Amount Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, before Tax Net unrealized (losses) gains, Before-tax Amount Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Tax Net unrealized (losses) gains on investment securities available for sale: Tax (Expense) Benefit Other Comprehensive Income (Loss), Securities, Available-for-sale, Tax [Abstract] Reclassification adjustment for net losses (gains) realized in net income, Tax (Expense) Benefit Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Net unrealized (losses) gains arising during the period, Tax (Expense) Benefit Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax Net unrealized (losses) gains, Tax (Expense) Benefit Other Comprehensive Income (Loss), Securities, Available-for-sale, Tax Net unrealized (losses) gains on investment securities available for sale: Net of Tax Amount Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax [Abstract] Reclassification adjustment for net losses (gains) realized in net income, Net of Tax Amount Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax Net unrealized gains (losses) arising during the period, Net of Tax Amount Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax Net unrealized (losses) gains, Net of Tax Amount Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax Post-retirement unfunded health benefit: Before-tax Amount Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax [Abstract] Reclassification adjustment for gains realized in net income, Before-tax Amount Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax Actuarial (losses) gains arising during the period, Before-tax Amount Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax Net decrease in unrealized gains, net, Before-tax Amount Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax Post-retirement unfunded health benefit: Tax (Expense) Benefit Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax [Abstract] Reclassification adjustment for gains realized in net income, Tax (Expense) Benefit Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax Actuarial (losses) gains arising during the period, Tax (Expense) Benefit Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, Tax Net decrease in unrealized gains, net, Tax (Expense) Benefit Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Post-retirement unfunded health benefit: Net of Tax Amount Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax [Abstract] Reclassification adjustment for gains realized in net income, Net of Tax Amount Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax Actuarial (losses) gains arising during the period, Net of Tax Amount Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax Net decrease in unrealized gains, net, Net of Tax Amount Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Other comprehensive (loss) income, Before-tax Amount Other Comprehensive Income (Loss), before Tax Other comprehensive (loss) income, Tax (Expense) Benefit Other Comprehensive Income (Loss), Tax Comprehensive income, Net of Tax Amount Comprehensive Income (Loss), Net of Tax, Attributable to Parent Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Summary of Derivative Instruments [Abstract] Derivative [Table] Derivative [Table] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Not Designated As Hedging Instruments Not Designated as Hedging Instrument [Member] Derivative Instrument Risk [Axis] Derivative Instrument [Axis] Derivative Contract Type [Domain] Derivative Contract [Domain] Mortgage derivatives Mortgage Derivative [Member] Mortgage Derivative [Member] Visa Derivative Other Contract [Member] Derivative Instruments, Gain (Loss) by Income Statement Location [Axis] Income Statement Location [Axis] Income Statement and Other Comprehensive Income Location [Domain] Income Statement Location [Domain] Other non-interest income Other Non Interest Income [Member] Other Non Interest Income [Member] Mortgage banking income Mortgage Banking Income [Member] Mortgage Banking Income [Member] Other non-interest expense Other Non-interest Expense [Member] Other Non-interest Expense [Member] Interest Rate Lock Commitments Interest Rate Lock Commitments [Member] Forward commitments to sell fixed-rate mortgage loans Forward commitments to sell fixed-rate mortgage loans [Member] Forward commitments to sell fixed-rate mortgage loans [Member] Derivative [Line Items] Derivative [Line Items] Total derivatives not designated as hedging instruments Derivative, Gain (Loss) on Derivative, Net Premises and Equipment Property, Plant and Equipment Disclosure [Text Block] Condensed Financial Information Disclosure [Abstract] Condensed Financial Statements [Table] Condensed Financial Statements [Table] Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Reclassification adjustment for losses realized in net income on cash flow hedges, Before-tax Amount Reclassification adjustment for losses realized in net income on cash flow hedges, Tax (Expense) Benefit Reclassification adjustment for net losses (gains) realized in net income on investment securities available for sale, Before-tax Amount Reclassification adjustment for net losses (gains) realized in net income on investment securities available for sale, Tax (Expense) Benefit Reclassification adjustment for net losses (gains) realized in net income on investment securities available for sale, Net of Tax Amount Net unrealized gains (losses) arising during the period, Tax (Expense) Benefit Other comprehensive (loss) gain of bank subsidiary, Before-tax Amount Other Comprehensive Income (Loss) of Subsidiaries, before Tax Other Comprehensive Income (Loss) of Subsidiaries, before Tax Other comprehensive (loss) gain of bank subsidiary, Tax (expense) Benefit Other Comprehensive Income (Loss) of Subsidiaries, Tax Other Comprehensive Income (Loss) of Subsidiaries, Tax Other comprehensive (loss) gain of bank subsidiary, Net of Tax Amount Other Comprehensive Income (Loss) of Subsidiaries, Net of Tax Other Comprehensive Income (Loss) of Subsidiaries, Net of Tax Accounting Policies [Abstract] Basis Of Presentation [Table] Basis Of Presentation [Table] Basis Of Presentation [Table] Loans Rating [Axis] Loans Rating [Axis] Loans Rating [Axis] Loans Rating [Domain] Loans Rating [Domain] [Domain] for Loans Rating [Axis] DRR Methodology DRR Methodology [Member] DRR Methodology [Member] Title of Individual [Axis] Title of Individual [Axis] Relationship to Entity [Domain] Relationship to Entity [Domain] Non-employee Director Non-employee Director [Member] Non-employee Director [Member] Non-employee Non-employee [Member] Non-employee [Member] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Cumulative-effect adjustment from adoption of ASU 2014-09 Accounting Standards Update 2014-09 [Member] Cumulative-effect adjustment from adoption of ASU 2016-01 Accounting Standards Update 2016-01 [Member] Accounting Standards Update 2016-02 Accounting Standards Update 2016-02 [Member] Retained Earnings Retained Earnings [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Forecast Scenario, Forecast [Member] Basis Of Presentation [Line Items] Basis Of Presentation [Line Items] Basis Of Presentation [Line Items] Cash and cash equivalents Cash On Deposit Per Federal Reserve Bank Requirements Cash on deposit to meet Federal Reserve Bank Requirements. Federal funds sold Short Term Investments Restricted Derivatives Short-term investments which are pledged in connection with derivative instruments. Retail loans and commercial loans, evaluated for impairment Retail Loans and Commercial Loans, Evaluated for Impairment Retail Loans and Commercial Loans, Evaluated for Impairment Separate account life insurance Separate Account Assets Useful life Property, Plant and Equipment, Useful Life Useful life Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Tax Cuts and Jobs Act of 2017, provisional income tax expense Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit) Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit) Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Increase in retained earnings Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings, Tax Effect Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings, Tax Effect Cumulative effect of new accounting principle in period of adoption Cumulative Effect of New Accounting Principle in Period of Adoption Hosting arrangements under service contract, costs capitalized Hosting Arrangements under Service Contract, Costs Capitalized Hosting Arrangements under Service Contract, Costs Capitalized Additional operating liabilities recognized as percent of total assets Additional Operating Liabilities Recognized as Percent of Total Assets Additional Operating Liabilities Recognized as Percent of Total Assets Sale leaseback gains Sale Leaseback Transaction, Deferred Gain, Net Schedule of Quarterly Financial Information Quarterly Financial Information [Table Text Block] Statement of Cash Flows [Abstract] Operating Activities Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation, amortization, and accretion, net Depreciation, Amortization and Accretion, Net Deferred income tax expense Deferred Income Tax Expense (Benefit) Originations of mortgage loans held for sale Payments for Origination of Mortgage Loans Held-for-sale Proceeds from sales of mortgage loans held for sale Proceeds from Sale of Mortgage Loans Held-for-sale Gain on sales of mortgage loans held for sale, net Gain (Loss) on Sale of Mortgage Loans Increase in other assets Increase (Decrease) in Prepaid Expense and Other Assets Increase (decrease) in other liabilities Increase (Decrease) in Other Accounts Payable and Accrued Liabilities Investment securities losses (gains), net Gain (Loss) on Investments Loss on early extinguishment of debt, net Gain (Loss) on Extinguishment of Debt Share-based compensation expense Share-based Compensation Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Investing Activities Net Cash Provided by (Used in) Investing Activities [Abstract] Net cash received in acquisition Net Cash (Used) Received in Dispositions / Acquisitions Net Cash (Used) Received in Dispositions / Acquisitions Proceeds from maturities and principal collections of investment securities available for sale Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale Proceeds from sales of investment securities available for sale Proceeds from Sale of Available-for-sale Securities Purchases of investment securities available for sale Payments to Acquire Available-for-sale Securities Proceeds from sales of loans Proceeds from Sale of Loans Held-for-investment Proceeds from sales of other real estate and other assets Proceeds from Sale of Other Real Estate Net increase in loans including purchases of loans Payments for (Proceeds from) Loans and Leases Net (purchases) redemptions of Federal Home Loan Bank stock Payments for (Proceeds from) Federal Home Loan Bank Stock Net (purchases) redemptions of Federal Reserve Bank stock Payments for (Proceeds from) Federal Reserve Bank Stock Purchases of bank-owned life insurance policies, net of settlements Payments to Acquire Bank Owned Life Insurance Policies (Settlements) Payments to Acquire Bank Owned Life Insurance Policies (Settlements) Net increase in premises and equipment Payments to Acquire Property, Plant, and Equipment Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Financing Activities Net Cash Provided by (Used in) Financing Activities [Abstract] Net increase in deposits Increase (Decrease) in Deposits Net increase (decrease) in federal funds purchased and securities sold under repurchase agreements Increase (Decrease) in Federal Funds Purchased and Securities Sold under Agreements to Repurchase, Net Net increase (decrease) in other short-term borrowings Payments for (Proceeds from) Short-term Investments Repayments and redemption of long-term debt Repayments of Long-term Debt Proceeds from issuance of long-term debt Proceeds from Issuance of Long-term Debt Dividends paid to common shareholders Payments of Ordinary Dividends, Common Stock Dividends paid to preferred shareholders Payments of Ordinary Dividends, Preferred Stock and Preference Stock Net proceeds from issuance of Series D Preferred Stock Proceeds from Issuance of Preferred Stock and Preference Stock Redemption of Series C Preferred Stock Payments for Repurchase of Preferred Stock and Preference Stock Stock options exercised Proceeds from Stock Options Exercised Earnout payment Payments Related To Earnout Liability Payments Related To Earnout Liability Repurchase of common stock Payments for Repurchase of Common Stock Taxes paid related to net share settlement of equity awards Taxes paid related to net share settlement of equity awards Taxes paid related to net share settlement of equity awards Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Increase (decrease) in cash and cash equivalents including restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect Cash, cash equivalents, restricted cash, and restricted cash equivalents at beginning of year Cash, cash equivalents, restricted cash, and restricted cash equivalents at end of year Supplemental Cash Flow Information Supplemental Cash Flow Information [Abstract] Income taxes, net Income Taxes Paid, Net Interest Interest Paid, Excluding Capitalized Interest, Operating Activities Non-cash Activities: Noncash Investing and Financing Items [Abstract] Loans foreclosed and transferred to other real estate Loans Foreclosed and Transferred to Other Real Estate Loans Foreclosed and Transferred to Other Real Estate Premises and equipment transferred to/(from) other assets, net Premises and Equipment Transferred to/(from) Other Assets, Net Premises and Equipment Transferred to/(from) Other Assets, Net Topic 606 cumulative-effect adjustment to opening balance of retained earnings Subtopic 825-10 equity investment securities available for sale transferred to other assets at fair value Investment securities available for sale transferred to trading account assets at fair value Investment securities available for sale transferred to trading account assets at fair value Loans transferred to (from) other loans held for sale at fair value, net Loans transferred to other loans held for sale at fair value Loans transferred to other loans held for sale at fair value Dividends declared on common stock during the year but paid after year-end Dividends Payable Settlement of earnout payment with shares of common stock Settlement of Earnout Payment with shares of common stock Settlement of Earnout Payment with shares of common stock Acquisition: Fair value of non-cash assets acquired Fair Value of Assets Acquired (Disposed) Fair Value of Assets Acquired (Disposed) Fair value of liabilities assumed Liabilities Assumed (Disposed) Liabilities Assumed (Disposed) Fair value of common stock issued Stock Issued Notional Amount Derivative, Notional Amount Fair Value of Derivative Assets Derivative Asset, Fair Value, Amount Not Offset Against Collateral Fair Value of Derivative Liabilities Derivative Liability, Fair Value, Amount Not Offset Against Collateral Operating Activities Net income Net Income (Loss) Attributable to Parent Adjustments to reconcile net income to net cash provided by operating activities: Equity in undistributed (income) loss of subsidiaries Equity in Undistributed Income (Loss) of Subsidiaries Equity in Undistributed Income (Loss) of Subsidiaries Deferred income tax expense Deferred Income Taxes and Tax Credits Net increase (decrease) in other liabilities Increase (Decrease) in Operating Liabilities Net decrease (increase) in other assets Increase (Decrease) in Operating Assets Other, net Other Operating Activities, Cash Flow Statement Investing Activities Net cash received (used) in acquisitions/dispositions Payments to Acquire Businesses, Net of Cash Acquired Net decrease in short-term notes receivable from non-bank subsidiaries Net (Increase) Decrease in Short-Term Notes Receivable from Non-Bank Subsidiaries Net (Increase) Decrease in Short-Term Notes Receivable from Non-Bank Subsidiaries Financing Activities Dividends paid to common and preferred shareholders Dividends Paid to Common and Preferred Shareholders Dividends Paid to Common and Preferred Shareholders Repurchases of common stock Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] Internal Credit Assessment [Domain] Internal Credit Assessment [Domain] Pass Pass [Member] Special Mention Special Mention [Member] Substandard Substandard [Member] Doubtful Doubtful [Member] Loss Loss And Charged Off [Member] Loss and Charged Off [Member] Financing Receivable, Recorded Investment [Line Items] Financing Receivable, Recorded Investment [Line Items] Total loans Performing, accrual of interest Loans and Leases Receivable, Performing, Accrual of Interest Loans and Leases Receivable, Performing, Accrual of Interest Allowance for loan and lease losses, percent of loan amount Allowance for Loan and Lease Losses, Percent of Loan Amount Allowance for Loan and Lease Losses, Percent of Loan Amount Statement of Stockholders' Equity [Abstract] Cash dividends declared on common stock, per share Common Stock, Dividends, Per Share, Cash Paid Income Statement [Abstract] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Service charges on deposit accounts Deposit Account [Member] Fiduciary and asset management fees Fiduciary and Trust [Member] Card fees Credit and Debit Card [Member] Brokerage revenue Investment Advisory, Management and Administrative Service [Member] Mortgage banking income Mortgage Banking [Member] Other fee income Financial Service, Other [Member] Interest income: Revenues [Abstract] Loans, including fees Interest and Fee Income, Loans and Leases Investment securities available for sale Interest Income on Available for Sale Securities Interest Income on Available for Sale Securities Mortgage loans held for sale Interest and Fee Income, Loans Held-for-sale, Mortgages Federal Reserve Bank balances Interest on Federal Reserve Bank balances Interest income earned on balances deposited with the Federal Reserve Bank. Other earning assets Interest Income, Deposits with Financial Institutions Total interest income Interest and Dividend Income, Operating Interest expense: Interest Expense [Abstract] Deposits Interest Expense, Deposits Federal funds purchased, securities sold under repurchase agreements, and other short-term borrowings Interest Expense, Short-term Borrowings Long-term debt Interest Expense, Long-term Debt Total interest expense Interest Expense Net interest income Interest Income (Expense), Net Net interest income after provision for loan losses Interest Income (Expense), after Provision for Loan Loss Non-interest income: Noninterest Income [Abstract] Revenue from contract with customer Revenue from Contract with Customer, Including Assessed Tax Income from bank-owned life insurance Bank Owned Life Insurance Income Cabela's Transaction Fee Fees and Commissions, Mortgage Banking and Servicing Investment securities (losses) gains, net Debt and Equity Securities, Gain (Loss) Other non-interest income Noninterest Income, Other Total non-interest income Noninterest Income Non-interest expense: Noninterest Expense [Abstract] Salaries and other personnel expense Labor and Related Expense Net occupancy and equipment expense Occupancy, Net Third-party processing expense Information Technology and Data Processing FDIC insurance and other regulatory fees F D I C Insurance And Other Regulatory Fees The premium paid to the Federal Deposit Insurance Corporation for deposit insurance plus other regulatory fees including examination fees and Federal Reserve service fees, all of which are included in noninterest expense. Professional fees Professional Fees Advertising expense Advertising Expense Foreclosed real estate expense, net Foreclosed Real Estate Expense Earnout liability adjustments Earnout Liability, Fair Value Adjustment Earnout Liability, Fair Value Adjustment Other operating expenses Other Noninterest Expense Total non-interest expense Noninterest Expense Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income tax expense Less: Preferred stock dividends and redemption charge Preferred Stock Dividends and Other Adjustments Net income available to common shareholders Net Income (Loss) Available to Common Stockholders, Basic Net income per common share, basic (in dollars per share) Earnings Per Share, Basic Net income per common share, diluted (in dollars per share) Earnings Per Share, Diluted Weighted average common shares outstanding, basic (in shares) Weighted Average Number of Shares Outstanding, Basic Weighted average common shares outstanding, diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Shareholder approved equity compensation plans for shares of Synovus stock Shareholder Approved Equity Compensation Plans for Shares of Synovus Stock [Member] Shareholder Approved Equity Compensation Plans for Shares of Synovus Stock [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Number of securities to be issued upon vesting of restricted share units (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Number of securities to be issued upon exercise of outstanding options (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number Weighted-average exercise price of outstanding options (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price Number of shares remaining available for issuance excluding shares discussed (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Loan Commitments and Letters of Credit Loan Commitments and Letters of Credit [Table Text Block] Loan Commitments and Letters of Credit [Table Text Block] Income Cash dividends received from subsidiaries Cash Dividends Received from Bank Subsidiaries Cash Dividends Received from Bank Subsidiaries Cash distributions received from Synovus Bank Cash Distributions Received from Bank Subsidiaries Cash Distributions Received from Bank Subsidiaries Interest income Investment Income, Interest Other (loss) income Other Income (Loss) Other Income (Loss) Total income Total Income Total Income Expenses Interest expense Other expenses Total expenses Total Expense Total Expense Income before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Allocated income tax benefit Income Tax Expense (Benefit), Intraperiod Tax Allocation Income before equity in undistributed income (loss) of subsidiaries Income (Loss) Before Equity in Undistributed Net Income (Loss) of Subsidiaries Income (Loss) Before Equity in Undistributed Net Income (Loss) of Subsidiaries Equity in undistributed income (loss) of subsidiaries Equity in Undistributed Income (Loss) from Continuing Operations of Subsidiaries Equity in Undistributed Income (Loss) from Continuing Operations of Subsidiaries Net income (loss) available to controlling interest Proceeds from sales of investment securities available for sale Proceeds from Sale of Debt Securities, Available-for-sale Gross realized gains on sales Available-for-sale Securities, Gross Realized Gains Gross realized losses on sales Available-for-sale Securities, Gross Realized Losses Investment securities (losses) gains, net Available-for-sale Securities, Gross Realized Gain (Loss) Subsequent Events Subsequent Events [Text Block] Income Tax Contingency [Table] Income Tax Contingency [Table] Federal and State Domestic Tax Authority and State and Local Jurisdiction [Member] Domestic Tax Authority and State and Local Jurisdiction [Member] Expiration Period [Axis] Expiration Period [Axis] Expiration Period [Axis] Expiration Period [Domain] Expiration Period [Domain] [Domain] for Expiration Period [Axis] Period through 2035 Period through 2035 [Member] Period through 2035 [Member] Period through 2027 Period through 2027 [Member] Period through 2027 [Member] Income Tax Contingency [Line Items] Income Tax Contingency [Line Items] Tax Cuts and Jobs Act of 2017, income tax benefit Tax Cuts and Jobs Act of 2017, Income Tax Expense (Benefit) Tax Cuts and Jobs Act of 2017, Income Tax Expense (Benefit) Tax Cuts and Jobs Act of 2017, measurement period adjustment, income tax benefit Tax Cuts and Jobs Act of 2017, Measurement Period Adjustment, Income Tax Expense (Benefit) Tax Cuts and Jobs Act of 2017, Measurement Period Adjustment, Income Tax Expense (Benefit) Tax Cuts and Jobs Act of 2017, measurement period adjustment, adjustment to prior year tax return Tax Cuts and Jobs Act of 2017, Measurement Period Adjustment, Adjustment To Prior Year Tax Return Tax Cuts and Jobs Act of 2017, Measurement Period Adjustment, Adjustment To Prior Year Tax Return Deferred tax assets expected to be realized Deferred Tax Assets, Amount Expected to be Realized Deferred Tax Assets, Amount Expected to be Realized Valuation allowance Deferred tax assets, not subject to expiration Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration Deferred tax assets, subject to expiration Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration Tax credit carryforward, amount Tax Credit Carryforward, Amount Unrecognized tax benefits, income tax penalties and interest accrued Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Unrecognized tax benefits that would impact effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Unrecognized tax benefits, income tax penalties and interest accrued that would impact effective tax rate Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued that Would Impact Effective Tax Rate Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued that Would Impact Effective Tax Rate Approximate range of uncertain income tax positions expected to be settled or resolved during the next 12 months, minimum Increase in Unrecognized Tax Benefits is Reasonably Possible Schedule of Non-interest Income Disaggregation of Revenue [Table Text Block] Schedule of Goodwill Schedule of Goodwill [Table Text Block] Schedule of Other Intangible Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Award Type and Plan Name [Axis] Award Type [Axis] Award Type [Domain] Equity Award [Domain] Market Restricted Share Units Market Restricted Stock Units (MRSUs) [Member] Market Restricted Stock Units (MRSUs) [Member] Performance Share Units Performance Share Units (PSUs) [Member] Performance Share Units (PSUs) [Member] Share Units Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Outstanding, Beginning of Period (in shares) Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Dividend equivalents granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Dividend Equivalents Grants in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Dividend Equivalents Grants in Period Quantity change by TSR factor (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Quantity Change by TSR Factor Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Quantity Change by TSR Factor Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Adjustment for performance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Adjusted for Performance Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Adjusted for Performance Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Outstanding, End of Period (in shares) Weighted-Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Outstanding, Beginning of Period, Weighted-Average Grant-date Fair Value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Granted, Weighted-Average Grant-date Fair Value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Dividend equivalents granted, Weighted-Average Grant-date Fair Value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Dividend Equivalents Grants in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Dividend Equivalents Grants in Period, Weighted Average Grant Date Fair Value Quantity change by TSR factor, Weighted-Average Grant-date Fair Value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Quantity Change by TSR Factor in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Quantity Change by TSR Factor in Period, Weighted Average Grant Date Fair Value Vested, Weighted-Average Grant-date Fair Value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Adjustment for performance, Weighted-Average Grant-date Fair Value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Adjusted for Performance, Weighted-Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Adjusted for Performance, Weighted-Average Grant Date Fair Value Forfeited, Weighted-Average Grant-date Fair Value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Outstanding, End of Period, Weighted-Average Grant-date Fair Value (in dollars per share) Investment Securities Available for Sale Available-for-sale Securities [Table Text Block] 7.875% Senior Notes due February 15, 2019 Seven Point Eight Seven Five Percent Senior Notes, Due February 15, 2019 [Member] 7.875% Senior Notes, Due February 15, 2019 [Member] 5.125% Subordinated Notes due June 15, 2017 Five Point One Two Five Percent Subordinated Notes, Due June 15, 2017 [Member] 5.125% Subordinated Notes, Due June 15, 2017 [Member] Loans Receivable Loans Receivable [Member] Proceeds from issuance of debt Proceeds from Issuance of Debt Loss on early extinguishment of debt Extinguishment of debt, amount Extinguishment of Debt, Amount Recorded balance loans receivable Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged Other intangible assets, gross carrying amount Finite-Lived Intangible Assets, Gross Other intangible assets, adjustment Finite-Lived Intangible Assets, Adjustments Finite-Lived Intangible Assets, Adjustments Other intangible assets, accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Other intangible assets, net carrying amount Finite-Lived Intangible Assets, Net Mortgage loans held for sale Change In Mortgage Loans Held For Sale Included In Net Income Changes in the fair value of mortgage loans held for sale that were included in the consolidated statements of income during the reporting period. Fair value Additional Collateral, Aggregate Fair Value Unpaid principal balance Fair value option, aggregate unpaid principal balance of mortgage loans held for sale Fair value option, aggregate unpaid principal balance of mortgage loans held for sale. Fair value less aggregate unpaid principal balance Fair Value, Option, Aggregate Differences, Long-term Debt Instruments Schedule of Condensed Balance Sheets Schedule Of Condensed Balance Sheets [Table Text Block] Schedule Of Condensed Balance Sheets [Table Text Block] Schedule of Condensed Statements of Operations Schedule of Condensed Statements of Operations [Table Text Block] Schedule of Condensed Statements of Operations [Table Text Block] Schedule of Condensed Statements of Comprehensive Income (Loss) Schedule of Condensed Statements of Comprehensive Income (Loss) [Table Text Block] Schedule of Condensed Statements of Comprehensive Income (Loss) [Table Text Block] Schedule of Condensed Statements of Cash Flows Schedule Of Condensed Statements Of Cash Flows [Table Text Block] Schedule Of Condensed Statements Of Cash Flows [Table Text Block] Loans And Allowance For Loan Losses Loans, Net of Unearned Income [Text Block] Schedule of Loans, Net of Unearned Income [Text Block] Condensed Financial Information Of Synovus Financial Corp. (Parent Company Only) Condensed Financial Information of Parent Company Only Disclosure [Text Block] Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Preferred stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Common stock, par value (per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares issued (in shares) Common Stock, Shares, Issued Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Treasury stock, shares at cost (in shares) Treasury Stock, Shares Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Community Banking Community Banking [Member] Community Banking [Member] Corporate Banking Corporate Banking [Member] Corporate Banking [Member]