Leases [Abstract] Leases Lessee, Operating Leases [Text Block] Operating leases, 2019 (three months remaining) Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year Operating leases, 2020 Lessee, Operating Lease, Liability, Payments, Due Year Two Operating leases, 2021 Lessee, Operating Lease, Liability, Payments, Due Year Three Operating leases, 2022 Lessee, Operating Lease, Liability, Payments, Due Year Four Operating leases, 2023 Lessee, Operating Lease, Liability, Payments, Due Year Five Operating leases, 2024 and beyond Lessee, Operating Lease, Liability, Payments, Due after Year Five Operating leases, total minimum payments Lessee, Operating Lease, Liability, Payments, Due Operating leases, interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Operating Leases, present value of lease liabilities Operating Lease, Liability Restructuring and Related Activities [Abstract] Project reserve Restructuring Reserve Organization, Consolidation and Presentation of Financial Statements [Abstract] Supplemental Balance Sheet Disclosures [Text Block] Supplemental Balance Sheet Disclosures [Text Block] Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Senior Notes Due November 2019 Senior Notes Due November 2019 [Member] Senior Notes Due November 2019 Senior Notes Due December 2020 Senior Notes Due December 2020 [Member] Senior Notes Due December 2020 Senior Notes Due May 2021 Senior Notes Due May 2021 [Member] Senior Notes Due May 2021 Senior Notes Due May 2023 Senior Notes Due May 2023 [Member] Senior Notes Due May 2023 Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Statistical Measurement [Axis] Statistical Measurement [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Debt Instrument [Line Items] Debt Instrument [Line Items] Debt repurchase amount Debt Instrument, Repurchase Amount Interest Expense, Debt Interest Expense, Debt Debt instrument interest rate stated percentage Debt Instrument, Interest Rate, Stated Percentage Share-based Payment Arrangement [Abstract] Schedule of Compensation Expense for Equity-Based Programs and Related Income Tax Benefits Schedule of Compensation Expense for Equity Programs and Related Tax Benefits [Table Text Block] Schedule of Compensation Expense for Equity Programs and Related Tax Benefits [Table Text Block] Income Tax Disclosure [Abstract] Reconciliation of Total Gross Unrecognized Tax Benefits Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table Text Block] Transfers and Servicing of Financial Assets [Abstract] Transfer of Financial Assets Accounted for as Sales [Table] Transfer of Financial Assets Accounted for as Sales [Table] Transfer of Accounts Receivable Programs [Axis] Transfer Of Accounts Receivable Programs [Axis] Transfer of Receivable Programs [Axis] Transfer of Accounts Receivable Programs [Domain] Transfer Of Accounts Receivable Programs [Domain] [Domain] for Transfer of Accounts Receivable Programs [Axis] Monetization Program Monetization Program [Member] Monetization Program. Kellogg Foreign Subsidiaries Other Program Kellogg Foreign Subsidiaries Other Program [Member] Other financing receivable programs through Kellogg foreign subsidiaries Qualitative and Quantitative Information, Transferred Financial Assets Qualitative and Quantitative Information, Transferor's Continuing Involvement, Transferred Financial Assets, by Transfer or Transferee [Axis] Qualitative and Quantitative Information, Transferred Financial Assets Qualitative and Quantitative Information, Transferor's Continuing Involvement in Transferred Financial Assets, Transfer or Transferee [Domain] Sold And Outstanding Accounts Receivable Sold And Outstanding [Member] Accounts Receivable Sold And Outstanding [Member] Maximum [Member] Maximum [Member] Amendments To Receivable Sales Agreement [Axis] Amendments To Receivable Sales Agreement [Axis] Amendments To Receivable Sales Agreement [Axis] Amendments To Receivable Sales Agreement [Domain] Amendments To Receivable Sales Agreement [Domain] [Domain] for Amendments To Receivable Sales Agreement [Axis] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other income (expense) Other Nonoperating Income (Expense) [Member] Transfer of Financial Assets Accounted for as Sales [Line Items] Transfer of Financial Assets Accounted for as Sales [Line Items] Transfers of Accounts Receivable Agreements Transfers Of Accounts Receivable Agreements Amount of cash proceeds that can be collected under transfer agreement Transfer of Financial Assets Accounted for as Sales, Amount Derecognized Transfer of Financial Assets Accounted for as Sales, Amount Derecognized Gain (Loss) on Sale of Accounts Receivable Gain (Loss) on Sale of Accounts Receivable Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Restructuring Type [Axis] Restructuring Type [Axis] Type of Restructuring [Domain] Type of Restructuring [Domain] Restructuring Plan [Axis] Restructuring Plan [Axis] Restructuring Plan [Domain] Restructuring Plan [Domain] COGS Cost of Sales [Member] Selling, General and Administrative Expenses Selling, General and Administrative Expenses [Member] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Domain] Other Comprehensive Income Location [Domain] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Restructuring charges Restructuring and Related Cost, Incurred Cost Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Goodwill [Table] Schedule of Goodwill [Table] Kashi Kashi [Member] Kashi reporting unit. Europe transfer to AMEA EuropeTransferToAMEA [Member] Europe transfer to AMEA. North America North America [Member] Reporting Unit [Axis] Reporting Unit [Axis] Reporting Unit [Domain] Reporting Unit [Domain] Goodwill [Line Items] Goodwill [Line Items] Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount Goodwill Goodwill Divestiture Goodwill Goodwill, Written off Related to Sale of Business Unit Divestiture net intangibles Indefinite-lived Intangible Assets, Written off Related to Sale of Business Unit Indefinite-lived Intangible Assets Acquired Indefinite-lived Intangible Assets Acquired Schedule of supplemental operating lease information ScheduleOfSupplementalOperatingLeaseInformation [Table Text Block] Tabular disclosure of supplemental operating lease information including operating cash flows from operating leases, right-of-use assets obtained in exchange for new operating leases, weighted-average remaining lease term for operating leases and weighted-average discount rate for operating leases. Operating leases future maturities Lessee, Operating Lease, Liability, Maturity [Table Text Block] Restructuring and Cost Reduction Activities Restructuring and Related Activities Disclosure [Text Block] Trade receivables Accounts Receivable, before Allowance for Credit Loss, Current Allowance for doubtful accounts Accounts Receivable, Allowance for Credit Loss, Current Redundable income taxes Income Taxes Receivable Other receivables Other Receivables Accounts receivable, net Accounts Receivable, after Allowance for Credit Loss, Current Raw materials and supplies Inventory, Raw Materials and Supplies, Net of Reserves Finished goods and materials in process Inventory, Finished Goods and Work in Process, Net of Reserves Inventories Inventory, Net Property Property, Plant and Equipment, Gross Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property, net Property, Plant and Equipment, Net Pension Assets for Plan Benefits, Defined Benefit Plan Deferred income taxes Deferred Tax Assets, Net, Noncurrent Other Other Assets, Miscellaneous, Noncurrent Other assets Other Assets, Noncurrent Accrued income taxes Accrued Income Taxes, Current Accrued salaries and wages Accrued Salaries, Current Accrued advertising and promotion Accrued Marketing Costs, Current Other Other Accrued Liabilities, Current Other current liabilities Other Liabilities, Current Income taxes payable Accrued Income Taxes, Noncurrent Nonpension postretirement benefits Liability, Other Postretirement Defined Benefit Plan, Noncurrent Other Other Sundry Liabilities, Noncurrent Other liabilities Other Liabilities, Noncurrent Components of Notes Payable Schedule of Short-term Debt [Table Text Block] Acquisitions, West Africa Investments, Goodwill and Other Intangible Assets [Abstract] Acquisitions, goodwill and other intangible assets disclosure abstract. Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Europe Europe [Member] Latin America Latin America [Member] AMEA AMEA [Member] Asia, Middle East and Africa reportable operating segment. Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Finite-lived Intangible Assets [Roll Forward] Finite-lived Intangible Assets [Roll Forward] Gross carrying amount, beginning balance Finite-Lived Intangible Assets, Gross Additions Finite-lived Intangible Assets Acquired Divestiture FiniteLivedIntangibleAssetsWrittenOffRelatedToSaleOfBusinessUnit Amount of divestiture of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually and separately recognized. Purchase price allocation adjustment Intangible Transfer Amount of transfers into (out of) an intangible asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Currency translation adjustment Finite Lived Intangible Assets, Foreign Currency Translation Gain (Loss) Gross carrying amount, ending balance Accumulated amortization, beginning balance Finite-Lived Intangible Assets, Accumulated Amortization Amortization Amortization of Intangible Assets Divestiture amortization AmortizationOfIntangibleAssetsWrittenOffRelatedToSaleOfBusinessUnit Write-off of accumulated amortization associated with reclassification to assets held for sale. Currency translation adjustment Finite Lived Intangible Assets Accumulated Amortization Foreign Currency Gain Loss Currency translation adjustment for accumulated amortization. Accumulated amortization, ending balance Intangible assets subject to amortization net, beginning balance Finite-Lived Intangible Assets, Net Additions Finite Lived Intangible Assets Acquired Net Amount of increase in assets, excluding financial assets, lacking physical substance with definite life, from an acquisition. Purchase price allocation adjustment Amortization Amortization Of Intangibles Net The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method. Currency translation adjustment Finite Lived Intangible Assets Foreign Currency Gain Loss Net Net finite lived intangible assets cumulated translation adjustment. Intangible assets subject to amortization net, ending balance Currently estimated aggregate annual amortization expense for full-year Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months Accounting Policies [Abstract] New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] AOCI AOCI Including Portion Attributable to Noncontrolling Interest [Member] Retained earnings Retained Earnings [Member] Cash Flow Location [Axis] Cash Flow Location [Axis] Cash Flow Location [Axis] Cash Flow Location [Domain] Cash Flow Location [Domain] [Domain] for Cash Flow Location [Axis] Impact of new accounting standards New Accounting Pronouncements or Change in Accounting Principle [Line Items] Reclassification of tax effects relating to U.S. tax reform TaxCutsandJobsActReclassificationfromAOCIToRetainedEarningsTaxEffect Tax Cuts and Jobs Act reclassification from AOCI to retained earnings tax effect. Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Operating lease liabilities Obligations placed in accounts payable tracking system Payables Placed On Tracking System Amount of payables financed by suppliers that had been placed on the accounts payable tracking system which facilitates participating suppliers' ability to finance payment obligations from the company with designated third party financial institutions. Obligations sold by participating suppliers Payables Financed By Participating Suppliers Amount of payment obligations sold to participating financial institution that were previously outstanding in the accounts payable tracking system. Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Granted, weighted-average exercise price (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Subsequent Events [Abstract] Subsequent Event [Table] Subsequent Event [Table] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] Cookies, fruit and fruit-flavored snacks, pie crusts and ice cream cones businesses Cookies Fruit And Fruit Snacks Businesses [Member] Cookies, fruit and fruit snacks, pie crusts and ice cream cones businesses. Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Line Items] Subsequent Event [Line Items] Retirement Benefits [Abstract] Components of Plan Benefit Expense Schedule of Defined Benefit Plans Disclosures [Table Text Block] Contributions to Employee Benefit Plans Schedule of Contributions to Employee Benefit Plans [Table Text Block] Schedule of Contributions to Employee Benefit Plans [Table Text Block] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Pension Pension Plan [Member] Other Nonpension Postretirement Other Nonpension Postretirement [Member] Other Nonpension Postretirement [Member] Postemployment Postemployment [Member] Postemployment [Member] Minimum [Member] Minimum [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Amortization of unrecognized prior service cost (gain) Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Recognized net (gain) loss Defined Benefit Plan, Amortization of Gain (Loss) Net periodic benefit cost Defined Benefit Plan Period Cost Gross Periodic benefit costs gross Curtailment (gain) loss Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment Total plan benefit (income) expense Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Basis of presentation Basis of Accounting, Policy [Policy Text Block] Accounts payable Payables Tracking System Policy [Policy Text Block] Describes an entity's policy to account for its agreement with a third party to provide an accounts payable tracking system which facilitates participating suppliers' ability to finance payment obligations from the company with designated third party financial institutions. New accounting standards adopted and accounting standards to be adopted in future periods New Accounting Pronouncements, Policy [Policy Text Block] Income Tax Contingency [Table] Income Tax Contingency [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Income Tax Authority, Name [Axis] Income Tax Authority, Name [Axis] Income Tax Authority, Name [Domain] Income Tax Authority, Name [Domain] Tax Period [Axis] Tax Period [Axis] Tax Period [Domain] Tax Period [Domain] Income Tax Contingency [Line Items] Income Tax Contingency [Line Items] Income tax related interest accrued Income Tax Examination, Penalties and Interest Accrued Tax settlement Tax Adjustments, Settlements, and Unusual Provisions Derivative Instruments and Fair Value Measurements [Abstract] Derivative instruments and fair value measurements Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Foreign currency exchange contracts Foreign Exchange Contract [Member] Cross currency interest rate contract Cross Currency Interest Rate Contract [Member] Interest rate contracts Interest Rate Contract [Member] Commodity contracts Commodity Contract [Member] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Notional amount of derivative Derivative, Notional Amount Equity [Abstract] Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Corporate bonds Corporate Debt Securities [Member] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income Reclassification out of Accumulated Other Comprehensive Income [Member] (Gains) losses on cash flow hedges Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member] Amortization of postretirement and postemployment benefits Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest [Member] (Gains) losses on available-for-sale securities AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Including Noncontrolling Interest [Member] Other income (expense), net Other Income (Expense), Net [Member] Other income (expense), net [Member] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] COGS Cost of Goods and Services Sold SG&A Selling, General and Administrative Expense Interest expense Interest and Debt Expense Net experience (gain) loss Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Prior service cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Other (Income) expense Other Nonoperating Income (Expense) Total before tax Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Tax expense (benefit) Income Tax Expense (Benefit) Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Statement of Financial Position [Abstract] Current assets Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Accounts receivable, net Inventories Other current assets Other Assets, Current Current assets held for sale Disposal Group, Including Discontinued Operation, Assets, Current Total current assets Assets, Current Property, net Other intangibles, net Intangible Assets, Net (Excluding Goodwill) Investments in unconsolidated entities Equity Method Investments Other assets Noncurrent assets held for sale Disposal Group, Including Discontinued Operation, Assets, Noncurrent Total assets Assets Current liabilities Liabilities, Current [Abstract] Current maturities of long-term debt Long-term Debt and Lease Obligation, Current Notes payable Short-term Debt Accounts payable Accounts Payable, Current Current operating lease liabilities Operating Lease, Liability, Current Other current liabilities Total current liabilities Liabilities, Current Long-term debt Long-term Debt and Lease Obligation Operating lease liabilities Operating Lease, Liability, Noncurrent Deferred income taxes Deferred Tax Liabilities, Net, Noncurrent Pension liability Liability, Defined Benefit Pension Plan, Noncurrent Other liabilities Commitments and contingencies Commitments and Contingencies Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Common stock, $.25 par value Common Stock, Value, Issued Capital in excess of par value Additional Paid in Capital, Common Stock Retained earnings Retained Earnings (Accumulated Deficit) Treasury stock, at cost Treasury Stock, Value Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Total Kellogg Company equity Stockholders' Equity Attributable to Parent Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest Total equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total liabilities and equity Liabilities and Equity Supplemental Financial Data Consolidated Balance Sheet [Table Text Block] Supplemental Financial Data Consolidated Balance Sheet [Table Text Block] Supplemental Financial Data Consolidated Balance Sheet [Table Text Block] Other Programs [Member] Other Projects [Member] Other restructuring projects [Member] Restructuring and related costs, expected cost Restructuring and Related Cost, Expected Cost Cash costs Effect on Future Cash Flows, Amount Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Deferred tax liability DeferredTaxLiability [Member] DeferredTaxLiability [Member] Other current liabilities Other Current Liabilities [Member] Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Income tax benefit related to transition tax liability Tax Cuts and Jobs Act, Change in Tax Rate, Deferred Tax Liability, Income Tax Benefit Employer discretionary contribution amount Defined Contribution Plan, Employer Discretionary Contribution Amount Discrete tax benefit Discrete Tax Benefit Discrete tax benefit associated with remeasurement of deferred taxes following a legal entity restructuring as well as the reduction in the U.S. Corporate tax rate associated with the U.S. Tax Cuts and Jobs Act of 2017. Income taxes paid Income Taxes Paid Unrecognized tax benefits Unrecognized Tax Benefits Projected additions to unrecognized tax benefits Increase in Unrecognized Tax Benefits is Reasonably Possible Unrecognized tax benefits that would affect the effective income tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Schedule of Multiemployer Plans [Table] Schedule of Multiemployer Plans [Table] Other liabilities Other Noncurrent Liabilities [Member] Multiemployer Plan Type [Axis] Multiemployer Plan Type [Axis] Multiemployer Plans Type [Domain] Multiemployer Plans Type [Domain] Multiemployer Plan Name [Axis] Multiemployer Plan Name [Axis] Multiemployer Plan Name [Domain] Multiemployer Plan Name [Domain] Collective Bargaining Arrangement [Axis] Collective Bargaining Arrangement [Axis] Collective Bargaining Arrangement [Domain] Collective Bargaining Arrangement [Domain] Multiemployer Plan, Plan Information [Axis] Multiemployer Plan, Plan Information [Axis] Multiemployer Plan, Plan Information [Domain] Multiemployer Plan, Plan Information [Domain] Multiemployer Plans [Line Items] Multiemployer Plans [Line Items] Pre tax charge multi-employer pension plan withdrawal MultiemployerPensionPlanWithdrawalPreTaxCharge Pre tax charge associated with Multiemployer pension plan withdrawal. Annual cash obligation Annual Cash Obligation Annual cash payments associated with multi-employer pension plan withdrawal obligation. Cash obligation period CashObligationPeriod The maximum number of years in which the Company is obligated to pay cash as a result of exiting multi-employer pension plans. Reclassifications Out of AOCI Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Summary of Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Schedule of Restructuring and Cost Reduction Activities Restructuring and Related Costs [Table Text Block] Schedule of Exit Cost Reserves Schedule of Restructuring Reserve by Type of Cost [Table Text Block] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Selling General and Administrative Expenses Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Pre-tax compensation expense Share-based Payment Arrangement, Expense Related income tax benefit Share-based Payment Arrangement, Expense, Tax Benefit Project K [Member] Project K [Member] Employee related costs Employee Severance [Member] Pension curtailment (gain) loss, net Benefit Plan Obligation Impact [Member] Benefit Plan Obligation Impact [Member] Asset impairment Asset Impairment [Member] Fixed Assets that are determined to be impaired and written down to their estimated fair value member Asset related costs Asset related costs [Member] Asset related cost excluding asset impairment charges member Other costs Other Restructuring [Member] Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] Liability, beginning balance Cash payments Payments for Restructuring Non-cash charges and other Restructuring Reserve, Accrual Adjustment Liability, ending balance Hedging Relationship [Axis] Hedging Relationship [Axis] Hedging Relationship [Domain] Hedging Relationship [Domain] Fair Value Hedges Fair Value Hedging [Member] Net Investment Hedging Net Investment Hedging [Member] Other current assets Other Current Assets [Member] Other assets Other Assets [Member] Other liabilities Other Liabilities [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Level 1 Fair Value, Inputs, Level 1 [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Designated as Hedging Instrument Designated as Hedging Instrument [Member] Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Fair Value Of Related Hedge Portion Of Long Term Debt Fair Value Of Related Hedge Portion Of Long Term Debt The fair value of the portion of fixed rate long-term debt, the hedged item, which is hedged with fixed-to-floating, interest rate swaps. Assets Derivative Asset, Fair Value, Gross Asset Liabilities Derivative, Net Liability Position, Aggregate Fair Value Long-term debt total, carrying value Long-term Debt Business Acquisition, Pro Forma Information [Table Text Block] Business Acquisition, Pro Forma Information [Table Text Block] Carrying Amount of Goodwill Schedule of Goodwill [Table Text Block] Intangible Assets Subject to Amortization Schedule of Finite-Lived Intangible Assets [Table Text Block] Intangible Assets Not Subject to Amortization Schedule of Indefinite-Lived Intangible Assets [Table Text Block] Operating Segments Operating Segments [Member] Corporate Corporate, Non-Segment [Member] Program costs to date Restructuring and Related Cost, Cost Incurred to Date Employee related costs Other costs Estimated after-tax cash costs for program, including incremental capital investments Schedule of Indefinite-Lived Intangible Assets [Table] Schedule of Indefinite-Lived Intangible Assets [Table] Indefinite-lived Intangible Assets [Line Items] Indefinite-lived Intangible Assets [Line Items] Indefinite-lived Intangible Assets [Roll Forward] Indefinite-lived Intangible Assets [Roll Forward] Intangible assets not subject to amortization, beginning balance Indefinite-lived Intangible Assets (Excluding Goodwill) Additions Divestiture Purchase price allocation adjustment Indefinite-lived Intangible Assets, Purchase Accounting Adjustments Currency translation adjustment Indefinite-lived Intangible Assets, Foreign Currency Translation Gain (Loss) Intangible assets not subject to amortization, ending balance Segment Reporting [Abstract] Reportable Segments Segment Reporting Disclosure [Text Block] Cash Flow Hedging Cash Flow Hedging [Member] Foreign currency denominated long-term debt Foreign Currency Denominated Long Term Debt [Member] COGS Interest expense Interest Expense [Member] Gain (loss) recognized in AOCI Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net Gain (loss) reclassified from AOCI into income Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net Gain (loss) recognized in income Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net Retirement Plan Sponsor Location [Axis] Retirement Plan Sponsor Location [Axis] Retirement Plan Sponsor Location [Domain] Retirement Plan Sponsor Location [Domain] UNITED STATES UNITED STATES United States Domestic Plan [Member] Nonpension postretirement Other Postretirement Benefits Plan [Member] Employer contributions to employee benefit plans Defined Benefit Plan, Plan Assets, Contributions by Employer Total current year projected employer contributions Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Lessee, Operating Lease, Term of Contract Lessee, Operating Lease, Term of Contract Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Common stock Common Stock [Member] Capital in excess of par value Additional Paid-in Capital [Member] Treasury stock Treasury Stock [Member] Accumulated other comprehensive income (loss) AOCI Attributable to Parent [Member] Total Kellogg Company equity Parent [Member] Non-controlling interests Noncontrolling Interest [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance Balance (in shares) Shares, Issued Common stock repurchases (in shares) Treasury Stock, Shares, Acquired Common stock repurchases Treasury Stock, Value, Acquired, Cost Method Net income Acquisition of noncontrolling interest-Multipro Noncontrolling Interest, Increase from Business Combination Sale of subsidiary shares to noncontrolling interest Noncontrolling Interest, Increase from Subsidiary Equity Issuance Dividends declared Dividends, Common Stock Distributions to Noncontrolling interest Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Stock compensation APIC, Share-based Payment Arrangement, Increase for Cost Recognition Stock options exercised and other (in shares) Stock Issued During Period, Shares, Stock Options Exercised and Other Number of share options (or share units) exercised during the current period. Number of shares of stock issued during the period that is attributable to transactions involving issuance of stock not separately disclosed. Stock options exercised and other Stock Issued During Period, Value, Stock Options Exercised and Other Stock Issued During Period, Value, Stock Options Exercised and Other Balance (in shares) Balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Statement of Cash Flows [Abstract] Operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to operating cash flows: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Postretirement benefit plan expense (benefit) Pension and Other Postretirement Benefits Cost (Reversal of Cost) Deferred income taxes Deferred Income Taxes and Tax Credits Stock compensation Share-based Payment Arrangement, Noncash Expense Multi-employer pension plan exit liability Gain on unconsolidated entities, net Equity Method Investment, Realized Gain (Loss) on Disposal Other Other Noncash Income (Expense) Postretirement benefit plan contributions Payment for Pension and Other Postretirement Benefits Changes in operating assets and liabilities, net of acquisitions: Increase (Decrease) in Operating Capital [Abstract] Trade receivables Increase (Decrease) in Accounts Receivable Inventories Increase (Decrease) in Inventories Accounts payable Increase (Decrease) in Accounts Payable All other current assets and liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net Net cash provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities Investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Additions to properties Payments to Acquire Property, Plant, and Equipment Acquisitions, net of cash acquired Payments for (Proceeds from) Previous Acquisition Divestitures Proceeds from Divestiture of Businesses Investments in unconsolidated entities Payments to Acquire Interest in Joint Venture Acquisition of cost method investments Acquisition Of Cost Method Investment The cash outflow associated with the investment in an entity accounted for under the cost method of accounting. Purchases of available for sale securities Payments to Acquire Debt Securities, Available-for-sale Sales of available for sale securities Proceeds from Sale of Debt Securities, Available-for-sale Other Payments for (Proceeds from) Other Investing Activities Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities Financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Net issuances (reductions) of notes payable Proceeds from (Repayments of) Notes Payable Issuances of long-term debt Proceeds from Issuance of Long-term Debt Reductions of long-term debt Repayments of Long-term Debt Debt redemption costs Payment for Debt Extinguishment or Debt Prepayment Cost Net issuances of common stock Proceeds from Issuance of Common Stock Common stock repurchases Payments for Repurchase of Common Stock Cash dividends Payments of Ordinary Dividends, Common Stock Other Proceeds from (Payments for) Other Financing Activities Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents Increase (decrease) in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Supplemental cash flow disclosures Supplemental Cash Flow Information [Abstract] Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activities Supplemental cash flow disclosures of non-cash investing activities Noncash Investing and Financing Items [Abstract] Additions to properties included in accounts payable Capital Expenditures Incurred but Not yet Paid Derivative Instruments and Fair Value Measurements Derivatives and Fair Value [Text Block] Income Statement [Abstract] Net sales Revenues Cost of goods sold Selling, general and administrative expense Operating profit Operating Income (Loss) Interest expense Other income (expense), net Income before income taxes Income taxes Earnings (loss) from unconsolidated entities Income (Loss) from Equity Method Investments Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to Kellogg Company Net Income (Loss) Attributable to Parent Per share amounts: Earnings Per Share [Abstract] Basic earnings (in dollars per share) Earnings Per Share, Basic Diluted earnings (in dollars per share) Earnings Per Share, Diluted Average shares outstanding: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Actual shares outstanding at period end (in shares) Common Stock, Shares, Outstanding Cover page. Entities [Table] Entities [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] 1.750% Senior Notes Due 2021 [Member] 1.750% Senior Notes Due 2021 [Member] 1.750% Senior Notes Due 2021 [Member] 0.800% Senior Notes Due 2022 [Member] 0.800% Senior Notes Due 2022 [Member] 0.800% Senior Notes Due 2022 [Member] 1.000% Senior Notes Due 2024 [Member] 1.000% Senior Notes Due 2024 [Member] 1.000% Senior Notes Due 2024 [Member] 1.250% Senior Notes Due 2025 [Member] 1.250% Senior Notes Due 2025 [Member] 1.250% Senior Notes Due 2025 [Member] Entity Information [Line Items] Entity Information [Line Items] Document Type Document Type Document Quarterly Report Document Quarterly Report Entity Registrant Name Entity Registrant Name Document Period End Date Document Period End Date Document Transition Report Document Transition Report Entity File Number Entity File Number Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province Entity Address, Postal Zip Code Entity Address, Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Entity Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Entity Common Stock, Shares Outstanding (in shares) Entity Common Stock, Shares Outstanding Amendment Flag Amendment Flag Document Fiscal Period Focus Document Fiscal Period Focus Document Fiscal Year Focus Document Fiscal Year Focus Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Debt Securities, Available-for-sale [Table] Debt Securities, Available-for-sale [Table] Level 2 Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Available-for-sale securities, cost Available-for-sale Securities, Amortized Cost Basis Available-for-sale securities, unrealized gain (loss) Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax Available-for-sale securities, market value Debt Securities, Available-for-sale Gain on sale of available-for-sale securities Debt Securities, Available-for-sale, Gain (Loss) Accounting Policies Significant Accounting Policies [Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Hedge Adjustment [Axis] Hedge Adjustment [Axis] Hedge Adjustment [Axis] Hedge Adjustment [Domain] Hedge Adjustment [Domain] [Domain] for Hedge Adjustment [Axis] Carrying amount of hedged liability Carrying Amount Of Hedged Liability [Member] Carrying amount of hedged liability Cumulative fair value adjustment Cumulative Fair Value Adjustment [Member] Cumulative fair value adjustment Hedging adjustment Hedging Adjustment [Member] Hedging adjustment Discontinued Hedges Discontinued Hedging [Member] Discontinued Hedges Position [Axis] Position [Axis] Position [Domain] Position [Domain] Current maturities of long-term debt Discontinued Operations and Disposal Groups [Abstract] Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] U.S. pension and nonpension postretirement plans Other Pension, Postretirement and Supplemental Plans [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Cash proceeds from sale of businesses Net assets Net Assets Gain (Loss) on Disposition of Business Gain (Loss) on Disposition of Business Disposition related transaction costs DispositionOfBusinessTransactionRelatedCosts Disposition of business transaction related costs. Curtailment gain Derivative [Table] Derivative [Table] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Five Largest Accounts Five Largest Accounts [Member] Five Largest Accounts [Member] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Customer Concentration Risk Customer Concentration Risk [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Trade receivables Accounts Receivable [Member] Accounts Receivable, Net Exchange-traded commodity Derivative [Line Items] Derivative [Line Items] Net deferred losses reported in AOCI to be reclassified into income in the next twelve months Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months Fair value of derivative instruments with credit-risk-related contingent features in a liability position Credit Risk Derivative Liabilities, at Fair Value Additional collateral required to be posted if the credit risk related contingent features were triggered Additional Collateral, Aggregate Fair Value Concentration of risk, derivative instruments assets Fair Value, Concentration of Risk, Derivative Instruments, Assets Collateral posted Collateral Already Posted, Aggregate Fair Value Derivative, Collateral, Obligation to Return Cash Derivative, Collateral, Obligation to Return Cash Margin deposits Margin Deposit Assets Concentration percentage Concentration Risk, Percentage Income Taxes Income Tax Disclosure [Text Block] Dividends declared Common Stock, Dividends, Per Share, Declared Revenue Revenue Benchmark [Member] Other (income) expense, net Restructuring and related costs since inception of program Equity Stockholders' Equity Note Disclosure [Text Block] Debt Debt Disclosure [Text Block] Offsetting [Abstract] Asset derivatives, Amounts Presented in the Consolidated Balance Sheet Derivative Asset Asset derivatives, Financial Instruments, Gross Amounts Not Offset in the Consolidated Balance Sheet Derivative Asset, Not Offset, Policy Election Deduction Asset derivatives, Cash Collateral Posted, Gross Amounts Not Offset in the Consolidated Balance Sheet Asset derivatives, Net Amount Derivative Asset, Fair Value, Offset Against Collateral, Net of Not Subject to Master Netting Arrangement, Policy Election Liability derivatives, Amounts Presented in the Consolidated Balance Sheet Derivative Liability Liability derivatives, Financial Instruments, Gross Amounts Not Offset in the Consolidated Balance Sheet Derivative Liability, Not Offset, Policy Election Deduction Liability derivatives, Cash Collateral Received, Gross Amounts Not Offset in the Consolidated Balance Sheet Derivative, Collateral, Right to Reclaim Cash Liability derivatives, net amount Derivative Liability, Fair Value, Offset Against Collateral, Net of Not Subject to Master Netting Arrangement, Policy Election Restructuring and related activities cash implementation costs recovery time frame Restructuring And Related Activities Cash Implementation Costs Recovery Timeframe Time frame expected to recover cash implementation costs associated with restructuring and related activities after completion of the program. Stock Compensation Share-based Payment Arrangement [Text Block] Schedule of Short-term Debt [Table] Schedule of Short-term Debt [Table] Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] U.S. commercial paper Commercial Paper [Member] Bank borrowings Notes Payable to Banks [Member] Short-term Debt [Line Items] Short-term Debt [Line Items] Principal amount Effective interest rate Debt Instrument, Interest Rate, Effective Percentage Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Beginning balance Additions, current year Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Reductions, current year Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions Additions, prior years Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Reductions, prior years Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Settlements Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Ending balance Change in carrying amount of goodwill Goodwill [Roll Forward] Beginning Balance Additions Goodwill, Acquired During Period Purchase price allocation adjustment Goodwill, Transfers Purchase price adjustment Goodwill, Purchase Accounting Adjustments Divestiture Currency translation adjustment Goodwill, Foreign Currency Translation Gain (Loss) Ending Balance Operating lease costs Operating Lease, Cost Schedule of Reportable Segment Information Schedule of Segment Reporting Information, by Segment [Table Text Block] Revenue from External Customers by Products and Services Revenue from External Customers by Products and Services [Table Text Block] Long-term debt, fair value Long-term Debt, Fair Value Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Number of operating segments Number of Operating Segments Operating profit Research and development expense Research and Development Expense Indirect excise tax liability reversal ExciseTaxLiabilityReversal Income effect of a reversal of an indirect excise tax liability associated with participation in a tax amnesty program. Acquisitions, West Africa Investments, Goodwill and Other Intangible Assets Acquisitions, Goodwill and Other Intangibles [Text Block] The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities.The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss. Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Restricted Stock Award, Forfeitures [Abstract] Award Type [Axis] Award Type [Axis] Award Type [Domain] Award Type [Domain] Restricted stock units Restricted Stock Units (RSUs) [Member] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Non-vested, beginning of year, 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 Non-vested, end of year, weighted-average grant-date fair value (in dollars per share) Class of Treasury Stock [Table] Class of Treasury Stock [Table] Share Repurchase Program [Axis] Share Repurchase Program [Axis] Share Repurchase Program [Domain] Share Repurchase Program [Domain] December 2017 Share Repurchase Program December Two Thousand Seventeen Share Repurchase Program [Member] December 2017 Share Repurchase Program [Member] Equity, Class of Treasury Stock [Line Items] Equity, Class of Treasury Stock [Line Items] Anti-dilutive potential common shares excluded from reconciliation Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Stock repurchase program, authorized amount Stock Repurchase Program, Authorized Amount Stock Repurchase Program, Remaining Authorized Repurchase Amount Stock Repurchase Program, Remaining Authorized Repurchase Amount Common stock repurchased (in shares) Common stock repurchased Operating Lease, Payments Operating Lease, Payments Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Operating Lease, Weighted Average Remaining Lease Term Operating Lease, Weighted Average Remaining Lease Term Operating Lease, Weighted Average Discount Rate, Percent Operating Lease, Weighted Average Discount Rate, Percent 2019 Award PerformanceSharesTargetGrantTwentyNineteen [Member] Performance shares target grant 2019. 2016 Award PerformanceSharesTargetGrantTwentySixteen [Member] Performance Shares Target Grant Twenty Sixteen [Member] Percentage of performance shares that may be earned upon performance Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Award vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Performance shares target grant distribution (in shares) Performance Share Target Grant Performance Share Target Grant Grant-date fair value of shares that correspond with target grants Performance share award settlement Performance Awards Settlement Stock Issued Value Performance Awards Settlement Stock Issued Value Europe Foreign Plan [Member] Expected return on plan assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets Recognized net (gain) loss Hedged items Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge Derivatives designated as hedging instruments Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments Gain (loss) reclassified from AOCI into income Minimum lease payments for real-estate leases signed but not yet commenced Unrecorded Unconditional Purchase Obligation Operating lease rent expense Operating Lease, Expense Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Snacks Retail Channel Snacks [Member] Retail Channel Snacks [Member] Cereal Retail Channel Cereal [Member] Retail Channel Cereal [Member] Frozen Frozen And Specialty Channels [Member] Frozen And Specialty Channels [Member] Noodles and other NoodlesandOther [Member] Noodles and other. Restructuring and related cost, expected cost allocation Restructuring And Related Cost Expected Cost Allocation Allocation amount expected to be recognized in earnings for the specified restructuring cost. Loss Contingency [Abstract] Contingencies Commitments and Contingencies Disclosure [Text Block] Employee Benefits Pension and Other Postretirement Benefits Disclosure [Text Block] Acquisitions, West Africa Investments, Goodwill and Other Intangibles Narrative [Abstract] Narrative [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Tolaram Africa Foods (TAF) PTE LTD Tolaram Africa Foods Pte Ltd [Member] Tolaram Africa Foods PTE LTD TAF Investment in Affiliated Food Manufacturer TAF Investment in Affiliated Food Manufacturer [Member] Tolaram Africa Foods (TAF) Investment in Affiliated Food Manufacturer. Affiliated Food Manufacturer Affiliated Food Manufacturer [Member] Affiliated Food Manufacturer [Member] Multipro Multipro [Member] Multipro [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Equity method investment incremental ownership percentage change Equity Method Investment Incremental Ownership Percentage Increase in the percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. Business Acquisition, Pro Forma Revenue Business Acquisition, Pro Forma Revenue Business Acquisition, Pro Forma Net Income (Loss) Business Acquisition, Pro Forma Net Income (Loss) Equity method investment, ownership percentage Equity Method Investment, Ownership Percentage Payments to acquire business, gross Payments to Acquire Businesses, Gross Purchase price adjustment Equity Method Investment, Realized Gain (Loss) on Disposal Equity method investment aggregate cost Equity Method Investment, Aggregate Cost Equity Method Investment, Other than Temporary Impairment Equity Method Investment, Other than Temporary Impairment Net income attributable to Kellogg Company Schedule of Total Notional Amounts of Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Schedule of Derivative Instruments in Statement of Financial Position Fair Value Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Schedule of Offsetting Assets Offsetting Assets [Table Text Block] Schedule of Offsetting Liabilities Offsetting Liabilities [Table Text Block] Schedule of the Effect of Derivative Instruments on the Consolidated Statements of Income and Comprehensive Income Derivative Instruments, Gain (Loss) [Table Text Block] Available-for-sale securities Available-for-sale Securities [Table Text Block] Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Foreign currency translation adjustments Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Cash flow hedges — unrealized net gain (loss) Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Postretirement and postemployment benefits: Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax [Abstract] Net experience gain (loss) Accumulated Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Tax Prior service credit (cost) Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), after Tax Available-for-sale securities unrealized net gain (loss) AOCI, Debt Securities, Available-for-sale, Adjustment, after Tax Total accumulated other comprehensive income (loss) Operating leases, future minimum payments due 2019 Operating Leases, Future Minimum Payments Due, Next Twelve Months Operating leases, future minimum payments due 2020 Operating Leases, Future Minimum Payments, Due in Two Years Operating leases, future minimum payments due 2021 Operating Leases, Future Minimum Payments, Due in Three Years Operating leases, future minimum payments due 2022 Operating Leases, Future Minimum Payments, Due in Four Years Operating leases, future minimum payments due 2023 Operating Leases, Future Minimum Payments, Due in Five Years Operating leases, future minimum payments due 2024 and beyond Operating Leases, Future Minimum Payments, Due Thereafter Operating leases, total minimum payments Operating Leases, Future Minimum Payments Due Transfers and Servicing of Financial Assets [Text Block] Transfers and Servicing of Financial Assets [Text Block] Statement of Comprehensive Income [Abstract] Other comprehensive income (loss), pre-tax: Other Comprehensive Income (Loss), before Tax [Abstract] Foreign currency translation adjustments, pre-tax Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax Cash flow hedges, pre-tax: Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax [Abstract] Unrealized gain (loss) on cash flow hedges, pre-tax Reclassification to net income, pre-tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax Postretirement and postemployment benefit amounts arising during the period, pre-tax: Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment and Tax [Abstract] Prior service credit (cost), pre-tax Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax Postretirement and postemployment benefits reclassification to net income, pre-tax: Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax [Abstract] Net experience (gain) loss Available-for-sale securities, pre-tax Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Tax [Abstract] Unrealized gain (loss) on available-for-sale securities, pre-tax Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, before Tax Reclassification to net income on available-for-sale securities, pre-tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax Other comprehensive income (loss), pre-tax Other Comprehensive Income (Loss), before Tax Other comprehensive income (loss), tax (expense) benefit Other Comprehensive Income (Loss), Tax [Abstract] Foreign currency translation adjustments, tax (expense) benefit Other Comprehensive Income (Loss), Foreign Currency Translation Gain (Loss) Arising During Period, Tax Cash flow hedges, tax (expense) benefit: Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax [Abstract] Unrealized gain (loss) on cash flow hedges, tax (expense) benefit Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Reclassification to net income, tax (expense) benefit Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax Postretirement and postemployment benefit amounts arising during the period, tax (expense) benefit: Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, Tax [Abstract] Prior service credit (cost), tax (expense) benefit Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Plan Amendments, Tax Effect Postretirement and postemployment benefits reclassification to net income, tax (expense) benefit: Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax [Abstract] Net experience loss, tax (expense) benefit Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, Tax Prior service cost, tax (expense) benefit Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax Available-for-sale securities, tax (expense) benefit Other Comprehensive Income (Loss), Securities, Available-for-sale, Tax [Abstract] Unrealized gain (loss) on available-for-sale securities, tax (expense) benefit Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax Reclassification to net income on available for sale of securities, tax (expense) benefit Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Other comprehensive income (loss), tax (expense) benefit Other Comprehensive Income (Loss), Tax Other comprehensive income (loss), after tax: Other Comprehensive Income (Loss), Net of Tax [Abstract] Foreign currency translation adjustments, after-tax Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax Cash flow hedges, after tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax [Abstract] Unrealized gain (loss) on cash flow hedges, after-tax Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Reclassification to net income, after-tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax Postretirement and postemployment benefit amounts arising during the period, after-tax: Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, after Tax [Abstract] Prior service credit (cost), after-tax Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), after Tax Postretirement and postemployment benefits reclassification to net income, after-tax: Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax [Abstract] Net experience (gain) loss, after-tax Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Prior service cost, after-tax Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax Available-for-sale securities, after tax Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax [Abstract] Unrealized gain (loss) on available-for-sale securities, after-tax Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax Reclassification to net income on available for sale securities, after tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Other comprehensive income (loss) attributable to noncontrolling interests Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest Comprehensive income attributable to Kellogg Company Comprehensive Income (Loss), Net of Tax, Attributable to Parent Equity Method Investments and Joint Ventures [Abstract] Equity Method Investments and Joint Ventures Disclosure [Text Block] Equity Method Investments and Joint Ventures Disclosure [Text Block]