State and local government US States and Political Subdivisions Debt Securities [Member] Due after ten years Available For Sale Securities Debt Maturities After Ten Years Fair Value Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Debt Maturities After Ten Years Fair Value Before Reclassification To Disposal Group Assets Held For Sale Contingencies and Other Matters Commitments and Contingencies Disclosure [Text Block] Debt-to-Value [Domain] Debt-to-Value [Domain] Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Cash, cash equivalents and restricted cash January 1, Cash, cash equivalents and restricted cash, September 30, Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations Impact of non-performance risk Fair Value Measurement, Non-Performance Risk Adjustment Fair Value Measurement, Non-Performance Risk Adjustment $400 million, Floating Rate Notes due 11/2020 Notes Due 2020, Floating Rate Interest, Express Scripts [Member] Senior notes payable with floating interest due in 2020. Debt assumed acquisition from Express Scripts. Statistical Measurement [Domain] Statistical Measurement [Domain] $121 million, 5.875% Notes due 2041 Notes Due 2041, 5.875% Interest [Member] Notes payable bearing interest at 5.875% due in 2041. Security Exchange Name Security Exchange Name Property and equipment, gross Finance Lease, Right-of-Use Asset, before Accumulated Amortization Net proceeds on issuance of long-term debt Proceeds from Issuance of Long-term Debt Insurance and contractholder liabilities classified as held for sale Disposal Group, Including Discontinued Operation, Current Insurance And Contractholder Liabilities Disposal Group, Including Discontinued Operation, Current Insurance And Contractholder Liabilities Reinsurance Disclosures [Abstract] Reinsurance Disclosures [Abstract] Total current liabilities Liabilities, Current $1,000 million, 3% Notes due 2023 Notes Due 2023, 3% Interest [Member] Senior notes payable bearing interest at 3% due in 2023. Debt assumed acquisition from Express Scripts. Gross losses on sales Debt Securities, Available-for-sale, Realized Loss Upper-medium grade and higher Nationally Recognized Statisical Rating Organizations (NRSRO), A- Or Higher [Member] Nationally Recognized Statisical Rating Organizations (NRSRO), A- Or Higher Assets Assets [Abstract] Operating and Finance Lease Right of Use ("ROU") Assets and Lease Liabilities Assets And Liabilities Lessee [Table Text Block] Tabular disclosure of lessee right-of-use assets and lease liabilities for operating and finance leases. Reinsurance recoverables Reinsurance Recoverables, Noncurrent Amount, after valuation allowance, recoverable after one year under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves. Insurance And Contractholder Liabilities [Table] Insurance And Contractholder Liabilities [Table] $1,250 Million, 3.40% Debt due March 15, 2050 3.40% Long-Term Debt Due March 15, 2050 [Member] 3.40% Long-Term Debt Due March 15, 2050 Accounting Policies [Abstract] Accounting Policies [Abstract] Other sales, maturities and repayments (primarily short-term and other long-term investments) Proceeds from Sale and Maturity of Other Investments Effect of issuing stock for employee benefit plans Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Current Short-term Investments [Abstract] Reinsurance recoverables Reinsurance Recoverables, Net Reinsurance Recoverables, Net Real estate investments Real Estate Investment [Member] Balance sheet location of non-current finance lease assets Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List] Realized Gains and Losses on Investments Realized Gain (Loss) on Investments [Table Text Block] Total Insurance And Contractholder Liabilities, Noncurrent, Including Disposal Groups Insurance And Contractholder Liabilities, Noncurrent, Including Disposal Groups Guaranteed Insurance Contract, Type of Benefit [Domain] Guaranteed Insurance Contract, Type of Benefit [Domain] Other transactions impacting noncontrolling interests Temporary Equity, Other Changes Deferred policy acquisition costs Increase (Decrease) in Deferred Policy Acquisition Costs Long-term debt Total long-term debt Long-term Debt and Lease Obligation New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Not rated Nationally Recognized Statisical Rating Organizations (NRSRO), Not Rated [Member] Nationally Recognized Statisical Rating Organizations (NRSRO), Not Rated Unpaid claims and claim expenses Liability For Claims And Claims Adjustment Expense Current Including Disposal Groups The amount (expected to be paid within one year) needed to reflect the estimated ultimate cost of settling claims relating to insured events that have occurred on or before the balance sheet date, whether or not reported to the insurer at that date. Maximum guarantee exposure Guarantor Obligations, Maximum Exposure, Undiscounted Lincoln National Life and Lincoln Life & Annuity of New York The Lincoln National Life Insurance Company And Lincoln Life And Annuity Of New York [Member] Reinsurance recoverables resulting from the 1998 sale of the Companys individual life insurance and annuity business. Adjustment for credit risk on derivatives assets Derivative Credit Risk Valuation Adjustment, Derivative Assets Pharmacy and service costs payable Pharmacy And Service Costs Payable Reflects amounts due to pharmacies for prescriptions filled through our retail network of pharmacies. Also includes amounts due to clients for their portion of rebates that must be contractually shared. Reinsurance recoverables classified as assets of business held for sale Disposal Group, Including Discontinued Operation, Reinsurance Recoverables Disposal Group, Including Discontinued Operation, Reinsurance Recoverables Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Reclassification adjustment for settlement (interest expense and other) Accumulated Defined Benefit Plans Adjustment Settlement [Member] Other non-current liabilities Other Liabilities, Noncurrent Other comprehensive income, net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Debt securities and equity securities Proceeds From Sale Of Debt And Equity Securities Proceeds from sales of debt and equity securities. Inventories Inventory, Net Measurement Frequency [Domain] Measurement Frequency [Domain] AOCI Stockholders' Equity, Policy [Policy Text Block] Current loans Financing Receivable, Not Past Due Equity securities with readily determinable fair values Equity securities Equity Securities Fv Ni Before Reclassification To Disposal Group Assets Held For Sale Equity Securities Fv Ni Before Reclassification To Disposal Group Assets Held For Sale Integration and transaction-related costs, pre-tax Integration and transaction-related costs (Selling, general and administrative expenses) Integration and transaction-related costs Transaction Related Costs Transaction-related costs primarily consisting of fees for legal, advisory and other professional services, amortization of Bridge Facility fees in 2018, as well as employee costs. Concentration percentage Concentration Risk, Percentage Allowance for credit losses Financing Receivable, Allowance For Credit Loss, Before Reclassification To Disposal Group, Assets Held For Sale Financing Receivable, Allowance For Credit Loss, Before Reclassification To Disposal Group, Assets Held For Sale Statement [Line Items] Statement [Line Items] Investments including assets of business held for sale Long Term Investments Before Reclassification To Disposal Group Assets Held For Sale Long Term Investments Before Reclassification To Disposal Group Assets Held For Sale Outstanding Employee Stock Options Not Included in the Computation of Diluted Earnings Per Share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Credit agreement term Debt Instrument, Term $1,000 million, 3.875% Notes due 2047 Notes Due 2047, 3.875% [Member] Notes payable bearing interest at 3.875% due October 15, 2047. Accounts Receivable, Net Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Debt extinguishment costs (Debt extinguishment costs) Debt extinguishment costs Special Item Charges Debt Extinguishment Costs Before Tax Special Item Charges Debt Extinguishment Costs Before Tax Measurement Input Type [Domain] Measurement Input Type [Domain] Group Disability and Other and International Markets Group Disability And Other And International Markets [Member] Group Disability And Other And International Markets Statement [Table] Statement [Table] Statistical Measurement [Axis] Statistical Measurement [Axis] Ongoing Operations Ongoing Operations [Member] Unusual or Infrequent Items, or Both [Abstract] Weighted Average Weighted Average [Member] Entity Small Business Entity Small Business Other Derivatives Swap [Member] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Debt Debt Disclosure [Text Block] Other premiums Other Premiums [Member] Other Premiums Medicare Advantage Medicare Advantage [Member] Amendment Flag Amendment Flag Deposits and interest credited to contractholder deposit funds Additions to Contract Holders Funds Interest accretion Short-duration Insurance Contracts, Discounted Liabilities, Interest Accretion Short-term investments and cash equivalents Cash Cash Equivalents And Short Term Investments Before Reclassification To Disposal Group Assets Held For Sale Cash Cash Equivalents And Short Term Investments Before Reclassification To Disposal Group Assets Held For Sale Corporate Corporate, Non-Segment [Member] Ceded Credit Risk, Reinsurer [Axis] Ceded Credit Risk, Reinsurer [Axis] Pricing Concessions Through Remaining Contract Term Pricing Concessions Through Remaining Contract Term [Member] Pricing concessions sought in litigation for remainder of contract term. Guaranteed separate accounts Guaranteed Separate Account Assets Before Reclassification To Disposal Group Assets Held For Sale The fair value of the assets held by the Entity for the benefit of separate account policyholders with guarantees. Gains (losses) reclassified from other comprehensive income into shareholders' net income Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax Organizational Efficiency Plan Restructuring and Related Activities Disclosure [Text Block] Measurement Frequency [Axis] Measurement Frequency [Axis] Litigation Matters and Regulatory Matters Litigation Matters And Regulatory Matters [Member] Litigation Matters And Regulatory Matters Financial Instruments [Domain] Financial Instruments [Domain] Allowance for Credit Losses Credit Loss, Financial Instrument [Policy Text Block] Maximum exposure to loss related to arrangements with variable interest entity Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount Fair Value Disclosures for Financial Instruments Not Carried at Fair Value Fair Value, by Balance Sheet Grouping [Table Text Block] Gain (loss) recognized in the income statement Derivative, Gain (Loss) on Derivative, Net GMIB Guaranteed Minimum Income Benefit [Member] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Net realized investment gains, excluding credit loss expense and asset write-downs Realized Investment Gain Loss Excluding Impairments The net realized gains or (losses) on investments during the period before impairments, including gains (losses) on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity. $1,250 million, 3.4% Notes due 2050 Notes Due 2050, 3.4% Interest [Member] Notes Due 2050, 3.4% Interest Other comprehensive income, net of tax Other Comprehensive Income (Loss), Net of Tax, Including Temporary Equity Other Comprehensive Income (Loss), Net of Tax, Including Temporary Equity Commitment and Contingencies Commitments and Contingencies, Policy [Policy Text Block] Ceded Credit Risk [Line Items] Ceded Credit Risk [Line Items] Revenue from External Customers Revenue from External Customers by Products and Services [Table Text Block] Allowance for current expected credit losses on accounts receivable Accounts Receivable, Allowance for Credit Loss, Current Short-term debt Debt, Current [Abstract] Payments for debt tender and redemption Payments For Debt Tender And Redemption Payments For Debt Tender And Redemption Total comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest, Including Temporary Equity Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest, Including Temporary Equity Selling, general and administrative expenses Selling, General and Administrative Expense 80% to 100% Debt-to-Value Ratio, 80 to 100 Percent [Member] $1,500 million, 4.8% Notes due 2046 Notes Due 2046, 4.8% Interest [Member] Senior notes payable bearing interest at 4.8% due in 2046. Debt assumed acquisition from Express Scripts. Due after ten years Available For Sale Securities Debt Maturities After Ten Years Amortized Cost Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Debt Maturities After Ten Years Amortized Cost Before Reclassification To Disposal Group Assets Held For Sale Other assets Other Assets, Noncurrent Average Debt Service Coverage Ratio Financing Receivable Credit Quality Debt Service Coverage Before Reclassification To Disposal Group Assets Held For Sale Represents ratio measuring the amount of property cash flow available for annual interest and principal payments on debt. Short Term Investments And Cash Equivalents [Axis] Short Term Investments And Cash Equivalents [Axis] Information by type of short-term investments and cash equivalent balance. TOTAL ASSETS Assets Foreign government Foreign government securities Debt Security, Government, Non-US [Member] Provision for loss contingency Loss Contingency Accrual, Provision Cash reclassified to assets of business held for sale Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Disposal Group, Including Discontinued Operations Insurance and Contractholder Liabilities Liability for Future Policy Benefits and Unpaid Claims Disclosure [Text Block] Long-term debt Long-term Debt and Lease Obligation [Abstract] Net translation gains (losses) on foreign currencies Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Including Temporary Equity Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Including Temporary Equity Unpaid Claims and Claims Expenses Unpaid Policy Claims and Claims Adjustment Expense, Policy [Policy Text Block] Number of reportable segments renamed Number Of Reportable Segments Renamed Number Of Reportable Segments Renamed Subsequent Event Type [Axis] Subsequent Event Type [Axis] Insurance liabilities Increase (Decrease) in Insurance Liabilities Antidilutive Securities [Axis] Antidilutive Securities [Axis] Investments, Debt and Equity Securities [Abstract] Net realized investment gains (losses) Realized investment losses (gains), net Net realized investment gains (losses), before income taxes Realized Investment Gain Loss The net realized gains or (losses) on investments during the period, including gains (losses) on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity. Debt securities and equity securities Payments To Acquire Debt And Equity Securities Payments To Acquire Debt And Equity Securities Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Domain] Other Other Reinsurers [Member] Other Reinsurers TOTAL LIABILITIES Liabilities Other investment asset write-downs Impairments On Investments Total Total impairments recorded in pre-tax realized investment losses Damages sought by Anthem Loss Contingency, Damages Sought, Value Retirement Plan Type [Axis] Retirement Plan Type [Axis] Other Operations Other Segments [Member] Fair Value Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value Before Reclassification To Disposal Group Assets Held For Sale Lower-medium grade Nationally Recognized Statisical Rating Organizations (NRSRO), BBB- To BBB+ Rating [Member] Nationally Recognized Statisical Rating Organizations (NRSRO), BBB- To BBB+ Rating Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Intenational Markets and Group Disability and Life International Markets Group Disability And Life [Member] The combination of the Group Disability and Life segment and International Markets segment. U.S. Medical premiums Integrated Medical Products [Member] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Inventories Increase (Decrease) in Inventories Fair Value Marketable Securities Before Reclassification To Disposal Group Assets Held For Sale Marketable Securities Before Reclassification To Disposal Group Assets Held For Sale Future policy benefits Liability for Future Policy Benefit, before Reinsurance Other, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Commitments And Contingencies [Table] Commitments And Contingencies [Table] Commitments And Contingencies [Table] Additional Paid-in Capital Additional Paid-in Capital [Member] Asset Class [Axis] Asset Class [Axis] Future policy benefits Liability For Future Policy Benefits Noncurrent Including Disposal Groups Amount of accrued obligation to policyholders that relates to insured events for long-duration contracts, expected to be paid after one year. Securities Priced by the Company Unobservable Inputs Developed By Company [Member] Significant unobservable inputs used in pricing Level 3 securities that were developed directly by the Company. Fair Value Measurements Fair Value of Financial Instruments, Policy [Policy Text Block] Total gains (losses) included in shareholders’ net income attributable to instruments held at the reporting date Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Attributed To Instruments Held Included In Earnings This element represents total gains or losses for the period (realized and unrealized), arising from assets included in income attributable to instruments held at the reporting date, measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in asset value. Schedule Of Short Term Investments And Cash Equivalents [Table] Schedule Of Short Term Investments And Cash Equivalents [Table] Schedule of short-term investments and cash equivalent balances. This table excludes restricted cash balances. Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Short Term Investments And Cash Equivalents [Line Items] Short Term Investments And Cash Equivalents [Line Items] Credit Rating, Nationally Recognized Statistical Rating Organization (NRSRO) [Domain] Credit Rating, Nationally Recognized Statistical Rating Organization (NRSRO) [Domain] Credit Rating, Nationally Recognized Statistical Rating Organization (NRSRO) Revolving Credit Facility Revolving Credit Facility [Member] Before-tax Special items Special Items Before Tax [Abstract] Variable Interest Entities Variable Interest Entity Disclosure [Text Block] Income before income taxes Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest $2,187 million, 3.75% Notes due 2023 Notes Due 2023, 3.75% Interest [Member] Senior notes payable bearing interest at 3.75% due in 2023. Debt issued to finance acquisition. Other transactions impacting noncontrolling interests Noncontrolling Interest Other Changes Other activity associated with noncontrolling interest that is not separately disclosed. Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward] Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward] Acquisitions, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Common stock, shares authorized (in shares) Common Stock, Shares Authorized Mortgage and other asset-backed securities Available For Sale Securities Debt Maturities Without Single Maturity Date Fair Value Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Debt Maturities Without Single Maturity Date Fair Value Before Reclassification To Disposal Group Assets Held For Sale Common stock equivalents (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Summarized Segment Financial Information Schedule of Segment Reporting Information, by Segment [Table Text Block] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Non-guaranteed separate accounts priced at NAV as a practical expedient Non Guaranteed Separate Account Assets Priced At Net Asset Value As A Practical Expedient Before Reclassification To Disposal Group Assets Held For Sale The fair value of the assets held by the Entity for the benefit of separate account policyholders without guarantees and priced at net asset value as a practical expedient. 364-day Revolving Credit Agreement, Maturing October 2020 Revolving Credit Agreemen 364 Day [Member] Income Statement [Abstract] Income Statement [Abstract] Accumulated Other Comprehensive (Loss) AOCI Attributable to Parent [Member] Debt Securities by Contractual Maturity Investments Classified by Contractual Maturity Date [Table Text Block] Secured Ceded Credit Risk, Secured [Member] Total Equity Securities, FV-NI And Without Readily Determinable Fair Value, And Hybrid Instruments, Amortized Cost, Before Reclassification To Disposal Group, Assets Held For Sale Equity Securities, FV-NI And Without Readily Determinable Fair Value, And Hybrid Instruments, Amortized Cost, Before Reclassification To Disposal Group, Assets Held For Sale Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Variable Interest Entity, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Fair Value Available For Sale Securities Fixed Maturities Fair Value Excluding Trading Hybrid Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Fixed Maturities Fair Value Excluding Trading Hybrid Before Reclassification To Disposal Group Assets Held For Sale Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Separate Accounts Policyholder Accounts, Policy [Policy Text Block] Collectibility of Risk Corridor Payments Collectibility Of Risk Corridor Payments Receivable [Member] Collectibility Of Risk Corridor Payments Receivable Insurance and contractholder liabilities classified as held for sale Disposal Group, Including Discontinued Operation, Noncurrent Insurance And Contractholder Liabilities Disposal Group, Including Discontinued Operation, Noncurrent Insurance And Contractholder Liabilities Other, including finance leases Other Short-Term Debt, Current Maturities Of Long-Term Debt, And Lease Obligations, Current Other Short-Term Debt, Current Maturities Of Long-Term Debt, And Lease Obligations, Current Amortized Cost Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract] $63 million, 7.65% Notes due 2023 Notes due 2023 7.65% Interest [Member] Notes payable bearing interest at 7.65% due in 2023. Amortized Cost Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Amortized Cost Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Amortized Cost Before Reclassification To Disposal Group Assets Held For Sale Future policy benefits Liability For Future Policy Benefits Current Including Disposal Groups Amount of accrued obligation to policyholders that relates to insured events for long-duration contracts, expected to be paid within one year. Corporate and government debt securities Corporate And Government Debt Securities [Member] This category includes information about debt securities that are issued by either a domestic or foreign corporate business entity with a promise of repayment. Pharmacy and service costs payable Increase Decrease In Pharmacy And Service Costs Payable Consolidation Items [Domain] Consolidation Items [Domain] Total of incurred but not reported liabilities plus expected claim development on reported claims, including reported claims in process Liability For Claims And Claims Adjustment Expense Excluding Physician Incentives And Other Expenses Represents the total liability for incurred but not reported claims plus expected claim development on reported claims, including reported claims in process. Excludes amounts due for physician incentives and other medical care expenses and services payable. Reserves for litigation matters, pre-tax Reserves for performance guarantees Loss Contingency Accrual Beginning balance Ending Balance Debt Securities, Available-for-sale, Allowance for Credit Loss Express Scripts Litigation with Anthem Express Scripts Litigation With Anthem [Member] Total Unrealized Depreciation Debt Securities, Available-For-Sale, Unrealized Loss Position, Accumulated Loss, Before Reclassification To Disposal Group, Assets Held-For-Sale Debt Securities, Available-For-Sale, Unrealized Loss Position, Accumulated Loss, Before Reclassification To Disposal Group, Assets Held-For-Sale Hedging Designation [Axis] Hedging Designation [Axis] Damages for Service Issues Damages For Service Issues [Member] Damages sought in litigation for service issues. Accounts receivable, net classified as assets of business held for sale Accounts receivable, net Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net Special item related to contractual adjustment for a former client Special Items. Increase (Decrease) To Revenues Special Items. Increase (Decrease) To Revenues Other comprehensive income (loss) before reclassifications, tax Other Comprehensive Income (Loss) before Reclassifications, Tax Damages sought by the complaint Gain Contingency, Unrecorded Amount Designated as Hedging Instrument Designated as Hedging Instrument [Member] Loss on repurchase of debt, after-tax Gain (Loss) On Extinguishment Of Debt, Net Of Tax Gain (Loss) On Extinguishment Of Debt, Net Of Tax Mortgage and other asset-backed securities Available For Sale Securities Debt Maturities Without Single Maturity Date Amortized Cost Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Debt Maturities Without Single Maturity Date Amortized Cost Before Reclassification To Disposal Group Assets Held For Sale Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Long-term Long-term Investments [Abstract] Percent of future claim payments reinsured Ceded Reinsurance Agreement Reinsured Risk Percentage Percent of future claim payments reinsured under reinsurance agreement(s), net of existing retrocessional arrangements at the time agreement was made. Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Unpaid claims classified as liabilities of business held for sale Liability For Claims And Claims Adjustment Expense Attributable To Disposal Groups Liability For Claims And Claims Adjustment Expense Attributable To Disposal Groups Ceded Credit Risk, Collateralization [Axis] Ceded Credit Risk, Collateralization [Axis] Allowance for receivables net current Allowance For Receivables Net Current Allowance For Receivables Net Current Aggregate principal amount of outstanding debt securities under tender offer and optional redemption Debt Instrument, Repurchased Face Amount Due after five years through ten years Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value Before Reclassification To Disposal Group Assets Held For Sale Remaining overall limit under reinsurance agreement Ceded Reinsurance Agreement, Coverage Limit, Amount Remaining Amount remaining of overall limit to claims covered under ceded reinsurance agreement. Number of external reinsurers Ceded Credit Risk Number Of External Reinsurers The number of external reinsurers underwriting credit risk ceded by the Company. Revenue from External Customer [Line Items] Revenue from External Customer [Line Items] Accrued expenses and other current liabilities Operating Lease, Liability, Current Weighted-average interest rate Short-term Debt, Weighted Average Interest Rate, at Point in Time $45 million, 8.3% Step Down Notes due 2033 Step Down Notes Due 2033, 8.3% Interest [Member] Step-down debt bearing interest at 8.3% due in 2033. Derivative assets Derivative Assets Before Reclassification To Disposal Group Assets Held For Sale Derivative Assets Before Reclassification To Disposal Group Assets Held For Sale Subtotal Separate Account Assets Classified In Fair Value Hierarchy Before Reclassification To Disposal Group Assets Held For Sale The fair value of the assets held by the Entity for the benefit of separate account policyholders classified in the fair value hierarchy. Number of VIEs Variable Interest Entities, Number Of Entities Variable Interest Entities, Number Of Entities Class of Financing Receivable [Domain] Class of Financing Receivable [Domain] Total Receivables, Net, Current, Including Disposal Groups Receivables, Net, Current, Including Disposal Groups Fair Value Measurements Fair Value Disclosures [Text Block] Settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements Investments purchased or originated: Payments to Acquire Investments [Abstract] Liability for Claims and Claims Adjustment Expense [Line Items] Liability for Claims and Claims Adjustment Expense [Line Items] Current year Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Non-controlling interest percentage Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage Assets of business held for sale Total assets of business held for sale Disposal Group, Including Discontinued Operation, Assets, Current Total purchases, sales and settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) Adjustment upon Adoption Cumulative Effect, Period of Adoption, Adjustment [Member] Additional paid-in capital Additional Paid in Capital, Common Stock Commitments to contribute additional cash, amount Variable Interest Entity Off Balance Sheet Commitment Amount The off-balance sheet obligation to contribute additional cash to limited partnerships. Entity Registrant Name Entity Registrant Name Subsequent Event Type [Domain] Subsequent Event Type [Domain] Investments classified as assets of business held for sale Disposal Group Including Discontinued Operation, Current Investments, Current Disposal Group Including Discontinued Operation, Current Investments, Current Financial assets at fair value: Assets, Fair Value Disclosure [Abstract] Paid costs related to: Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract] Impairments of long-lived assets Asset Impairment Charges Intersegment Eliminations Intersegment Eliminations [Member] Due after one year through five years Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost Before Reclassification To Disposal Group Assets Held For Sale Investments Credit Rating [Domain] Investments Credit Rating [Domain] External credit-ratings or internal groupings that could be used to describe the current status of the payment and performance risk of debt and securities investments. Real estate funds priced at NAV as a practical expedient Fair Value Alternative Investment, Before Reclassification To Disposal Group, Assets Held For Sale Alternative Investment, Before Reclassification To Disposal Group, Assets Held For Sale $1,000 million, 3.5% Notes due 2024 Notes Due 2024 3.5% Interest [Member] Senior notes payable bearing interest at 3.5% due in 2024. Debt assumed acquisition from Express Scripts. Total Insurance And Contractholder Liabilities [Abstract] Insurance And Contractholder Liabilities Acquisition, disposition or runoff activities Acquisition Disposition Runoff Activities [Member] Products related to acquisition, disposition or runoff activities. Equity securities Equity Securities [Member] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Investments [Abstract] Held-for-Sale Disposal Group, Held-for-sale, Not Discontinued Operations [Member] $2,200 million, 4.125% Notes due 2025 Notes Due 2025, 4.125% Interest [Member] Senior notes payable bearing interest at 4.125% due in 2025. Debt issued to finance acquisition. Commercial mortgage loans Mortgage Loans On Real Estate Commercial And Consumer Net Before Reclassification To Disposal Group Assets Held For Sale Mortgage Loans On Real Estate Commercial And Consumer Net Before Reclassification To Disposal Group Assets Held For Sale Restricted cash and cash equivalents, included in other long-term investments Restricted Cash, Noncurrent Notional value Derivative Notional Amount Before Reclassification To Disposal Group Assets Held For Sale Derivative Notional Amount Before Reclassification To Disposal Group Assets Held For Sale Entity Address, Postal Zip Code Entity Address, Postal Zip Code Redemption Notice Period Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period Allowance for credit losses Financing Receivable, After Allowance For Credit Loss, Before Reclassification To Disposal Group, Assets Held For Sale Financing Receivable, After Allowance For Credit Loss, Before Reclassification To Disposal Group, Assets Held For Sale $600 million, 3.05% Notes due 2027 Notes Due 2027, 3.05% [Member] Notes payable bearing interest at 3.05% due October 15, 2027. Goodwill Goodwill Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Fair Value and Significant Unobservable Inputs Used in Pricing Debt Securities Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Investments Credit Rating [Axis] Investments Credit Rating [Axis] Information by credit rating of debt and securities investments. Common dividends declared (in dollars per share) Common Stock, Dividends, Per Share, Declared Reinsurance recoverables Reinsurance Recoverables Including Disposal Groups Reinsurance Recoverables Including Disposal Groups Face value Aggregate principal amount Principal Debt Instrument, Face Amount (Benefits) charges associated with litigation matters (Selling, general and administrative expenses) (Benefits) charges associated with litigation matters Special Item Charge BeforeTax Litigation After-tax charges associated with litigation matters that are classified as special items, attributable to the parent. Special items reflect amounts that management does not believe are representative of underlying results of operations. Separate account assets Separate account assets per Consolidated Balance Sheets Separate Account Asset Other current assets Other Assets, Current Asset Class [Domain] Asset Class [Domain] $190 million, 6.15% Notes due 2036 Notes due 2036 6.15% Interest [Member] Notes payable bearing interest at 6.15% due in 2036. Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Assets and Liabilities of Business Held for Sale Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Performance Guarantee Performance Guarantee [Member] Accounting Standards Update [Extensible List] Accounting Standards Update [Extensible List] Insurance and contractholder liabilities Insurance and contractholder liabilities classified as held for sale Disposal Group,Including Discontinued Operation, Insurance And Contractholder Liabilities Disposal Group,Including Discontinued Operation, Insurance And Contractholder Liabilities Less: Reinsurance and other amounts recoverable Add: Reinsurance and other amounts recoverable Reinsurance Recoverable for Unpaid Claims and Claims Adjustments Derivative Contract [Domain] Derivative Contract [Domain] Total shares (in shares) Weighted Average Number of Shares Outstanding, Diluted Contractholder deposit funds Policyholder Contract Deposits Noncurrent Including Disposal Groups The liability as of the balance sheet date to the policyholders for deposits held under the terms of insurance contracts, expected to be paid after one year. Financial Assets and Financial Liabilities Carried at Fair Value Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Below 60% LTV Less Than 60 Percent [Member] Letter of Credit Letter of Credit [Member] Aggregate principal amount of outstanding debt securities repurchased under optional redemption Debt Instrument, Repurchased Face Amount, Optional Redemption Debt Instrument, Repurchased Face Amount, Optional Redemption Contractual adjustment for a former client (Pharmacy revenues) Special Item, Gain (Loss) From Contract Adjustment, Net Of Tax Special Item, Gain (Loss) From Contract Adjustment, Net Of Tax Debt Disclosure [Abstract] Debt Disclosure [Abstract] Hybrid equity securities Equity Securities, Hybrid Instruments, Amortized Cost, Before Reclassification To Disposal Group, Assets Held For Sale Equity Securities, Hybrid Instruments, Amortized Cost, Before Reclassification To Disposal Group, Assets Held For Sale Revolving Credit Agreement Revolving Credit And Letter Of Credit Facility [Member] Arrangement in which loan proceeds can continuously be obtained following repayments, but the total amount borrowed cannot exceed a specified maximum amount. Evernorth Health Services [Member] Health Services includes pharmacy benefits management (PBM), pharmacy home delivery, and certain medical management services. This segment includes Express Scripts business from the date of acquisition with the exception of Express Scripts Medicare Part D business that is reported in the Government operating segment. Other liabilities Disposal Group, Including Discontinued Operation, Other Liabilities, Current NET CASH (USED IN) FINANCING ACTIVITIES  Net Cash Provided by (Used in) Financing Activities Repayment of long-term debt Repayment of long-term debt Repayments of Long-term Debt Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Medical costs and other benefit expenses Policyholder Benefits and Claims Incurred, Net 60% to 79% LTV 60 to 79 Percent [Member] Investments by Consolidated and Nonconsolidated Entities [Domain] Investments by Consolidated and Nonconsolidated Entities [Domain] Common stock Common Stock, Value, Issued Long-term investments Investments per Consolidated Balance Sheets Long-term Investments Document Fiscal Year Focus Document Fiscal Year Focus Net income attributable to other noncontrolling interests Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest Reinsurance recoverable and Other assets Increase (Decrease) in Reinsurance Recoverable Revenues from customers Total revenues from external customers Non Investment Revenue Revenue excluding net investment income and realized investment results. Current maturities Long-term Debt, Current Maturities Entity Current Reporting Status Entity Current Reporting Status Amounts included in shareholders net income for GMIB liabilities Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings Short-term debt Total short-term debt Debt, Current Actual completion factors Completion Factors [Member] Amounts relating to actual claims emerging differently from assumptions about claim payment speed used to set reserves. Noninsurance customer receivables Noninsurance Customer Receivables Excluding Pharmaceutical Manufacturers Receivable Receivables due from customers that are not under insurance contracts. These include pharmacy sales and fees due from employer clients. Foreign currency swap contracts Currency Swap [Member] Charge for organizational efficiency plan, pre-tax Charge for organizational efficiency plan (Selling, general and administrative expenses) Charge for organizational efficiency plan Organizational Efficiency Plan Charges Organizational Efficiency Plan Charges Debt-to-Value [Axis] Debt-to-Value [Axis] $3,800 million, 4.375% Notes due 2028 Notes Due 2028, 4.375% Interest [Member] Senior notes payable bearing interest at 4.375% due in 2028. Debt issued to finance acquisition. Common stock, shares issued (in shares) Common Stock, Shares, Issued Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Total operating lease liabilities Operating Lease, Liability Reinsurance Recoverables by Range of External Credit Rating and Collateral Level Ceded Credit Risk [Table Text Block] Prepayment rate Debt Instrument, Covenant, Conditional Prepayment Percentage Debt Instrument, Covenant, Conditional Prepayment Percentage Long-term debt Long-term Debt, Excluding Current Maturities Segment Reporting [Abstract] Segment Reporting [Abstract] Separate account assets of business classified as held for sale Disposal Group Including Discontinued Operation, Separate Account Assets, Current Disposal Group Including Discontinued Operation, Separate Account Assets, Current Debt Instrument [Line Items] Debt Instrument [Line Items] TOTAL SHAREHOLDERS’ EQUITY Beginning balance Ending balance Stockholders' Equity Attributable to Parent Separate account liabilities Separate Account, Liability Decrease for debt securities where credit losses have previously been recorded Debt Securities, Available-for-sale, Allowance for Credit Loss, Previously Recorded Debt Securities, Available-for-sale, Allowance for Credit Loss, Previously Recorded Description of Business Nature of Operations [Text Block] Entity Address, City or Town Entity Address, City or Town Pricing Concessions After Remaining Term of Agreement Pricing Concessions After Remaining Term Of Agreement [Member] Pricing concessions sought in litigation for one year arfter contract termination. Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Cigna Litigation with Anthem Cigna Litigation With Anthem [Member] Cigna Litigation With Anthem Shareholders’ Equity Parent [Member] Financial Instrument [Axis] Financial Instrument [Axis] Less: Reinsurance and other amounts recoverable Add: Reinsurance and other amounts recoverable Reinsurance Recoverable For Unpaid Claims And Claims Adjustments Including Disposal Groups Reinsurance Recoverable For Unpaid Claims And Claims Adjustments Including Disposal Groups Pharmacy revenues Product [Member] Liabilities Liabilities [Abstract] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Ceded Credit Risk [Table] Ceded Credit Risk [Table] $78 million, 6.37% Notes due 6/2021 Notes due 2021 6.37% Interest [Member] Notes payable bearing interest at 6.37% due in 2021. Long-term debt Finance Lease, Liability, Noncurrent Pharmacy Benefits Management Services Pharmacy Benefits Management Services [Member] Pharmacy benefit management services provided to corporate client, other employer groups and their employees. These services include pharmacy home delivery, retail network administration and specialty pharmacy Other comprehensive income (loss) Shareholders other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax Leases [Abstract] Leases [Abstract] Unearned premiums Unearned Premiums Including Disposal Groups Unearned Premiums Including Disposal Groups Noncatastrophic Event [Domain] Noncatastrophic Event [Domain] Benefits and expenses Benefits, Losses and Expenses [Abstract] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] COVID-19 COVID-19 Pandemic [Member] COVID-19 Pandemic Total current assets Assets, Current Effects of Reinsurance [Table] Effects of Reinsurance [Table] Total comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Earnings Per Share [Abstract] Earnings Per Share [Abstract] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] NAV Fair Value Measured at Net Asset Value Per Share [Member] Reductions for securities sold during the period Debt Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold Postretirement benefits liability Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Disposal Group Name [Domain] Disposal Group Name [Domain] Average Loan-to-Value Ratio Financing Receivable Credit Quality Loan To Value Ratio, Before Reclassification To Disposal Group, Assets Held For Sale Represents the percentage of the amount of loan to the fair value of the underlying property collateralizing the loan. Document Fiscal Period Focus Document Fiscal Period Focus $1,000 million, Floating Rate Notes due 2021 Notes Due 2021 Floating Rate Interest [Member] Senior notes payable with floating interest due in 2021. Debt issued to finance acquisition. Activity, including transfers in and out of Level 3 Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Asset, Period Increase (Decrease), Including Disposal Groups Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Period Increase (Decrease), Before Reclassification To Disposal Groups, Assets Held For Sale Derivative liabilities Derivative Liabilities Before Reclassification To Disposal Group Liabilities Held For Sale Derivative Liabilities Before Reclassification To Disposal Group Liabilities Held For Sale $1,750 million, 3.2% Notes due 9/2020 Notes Due 2020, 3.2% Interest [Member] Senior notes payable bearing interest at 3.2% due in 2020. Debt issued to finance acquisition. Adjusted revenues Segment Revenues Total revenues less realized investment gains from equity method subsidiaries, special items and other reconciling items determined by management. Commercial mortgage loans Mortgages [Member] Other long-term investments Other Long-term Investments [Member] Entity Filer Category Entity Filer Category Common Stock Common Stock [Member] Translation of foreign currencies Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Product and Service [Domain] Product and Service [Domain] Charge for organizational efficiency plan, after-tax Charge for organizational efficiency plan (Selling, general and administrative expenses) Organizational Efficiency Plan Charges, Net Of Tax Organizational Efficiency Plan Charges, Net Of Tax Net realized investment results from certain equity method investments Realized Investment Gains Losses Equity Method Investments Adjustment to exclude net realized gains (losses) from equity method subsidiaries (recorded in Other revenues) from Operating revenues. Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] $317 million, 5.375% Notes due 2042 Notes Due 2042, 5.375% Interest [Member] Notes payable bearing interest at 5.375% due in 2042. Fair Value Debt securities Available For Sale Securities Debt Securities Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Debt Securities Before Reclassification To Disposal Group Assets Held For Sale Impairments of equity securities related to value changes resulting from observable prices Realized investment losses on equity securities with no readily determinable fair value Equity Securities without Readily Determinable Fair Value, Downward Price Adjustment, Annual Amount Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Unusual or Infrequent Item, or Both [Domain] Unusual or Infrequent Item, or Both [Domain] Stated interest rate Interest rate Debt Instrument, Interest Rate, Stated Percentage $1,500 million, 3.4% Notes due 2027 Notes Due 2027, 3.4% Interest [Member] Senior notes payable bearing interest at 3.4% due in 2027. Debt assumed acquisition from Express Scripts. Number of Issues Available For Sale Securities In Unrealized Loss Positions, Qualitative Disclosure, Twelve Months Or Longer, Number Of Positions, Before Reclassification To Disposal Group, Assets Held For Sale Available For Sale Securities In Unrealized Loss Positions, Qualitative Disclosure, Twelve Months Or Longer, Number Of Positions, Before Reclassification To Disposal Group, Assets Held For Sale $1,250 million, 3.4% Notes due 2021 Notes Due 2021, 3.4% Interest [Member] Senior notes payable bearing interest at 3.4% due in 2021. Debt issued to finance acquisition. Unearned premiums Unearned Premiums Noncurrent Including Disposal Groups Carrying amount of premiums written on insurance contracts that have not been earned as of the balance sheet date, expected to be paid after one year. Net increase in cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Mergers and Acquisitions Business Combination Disclosure [Text Block] Medicare Part D Medicare Part D [Member] A government health plan for prescription drugs. Account Value, Net Amount at Risk and the Number of Contractholders for Guarantees Assumed in the Event of Death Schedule of Net Amount of Risk by Product and Guarantee [Table Text Block] Variances in Incurred Costs Related to Prior Years' Unpaid Claims and Claims Expenses Schedule of Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] 364-day Revolving Credit Agreement, Maturing October 2021 364 Day Revolving Credit Agreement, Maturing October 2021 [Member] 364 Day Revolving Credit Agreement, Maturing October 2021 Employee Stock Options Share-based Payment Arrangement, Option [Member] Shares of common stock held in treasury (in shares) Treasury Stock, Shares Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activities Total equity Balance Balance Stockholders' equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Short Term Investments And Cash And Cash Equivalents [Domain] Short Term Investments And Cash And Cash Equivalents [Domain] Type of short-term investments and cash equivalents. Number of operating segments renamed Number Of Operating Segments Renamed Number Of Operating Segments Renamed Total revenues Revenues Current year Current Year Claims and Claims Adjustment Expense Summary of Derivative Instruments Held Schedule of Derivative Instruments [Table Text Block] Schedule of Derivative Assets at Fair Value Schedule of Derivative Assets at Fair Value [Table Text Block] Income taxes paid, net of refunds Income Taxes Paid, Net Effect of foreign currency rate changes on cash, cash equivalents and restricted cash Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations New Accounting Pronouncements or Change in Accounting Principle [Table] Accounting Standards Update and Change in Accounting Principle [Table] Diluted (in dollars per share) EPS, diluted (in dollars per share) Earnings Per Share, Diluted Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Proceeds from sales Proceeds from Sale of Debt Securities, Available-for-sale Unrealized Depreciation Available For Sale Securities Continuous Unrealized Loss Position Less Than 12 Months Accumulated Loss Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Continuous Unrealized Loss Position Less Than 12 Months Accumulated Loss Before Reclassification To Disposal Group Assets Held For Sale Policy loans Policy Loans [Member] Total Number of Issues Available For Sale Securities In Unrealized Loss Positions, Qualitative Disclosure, Number Of Positions, Before Reclassification To Disposal Group, Assets Held For Sale Available For Sale Securities In Unrealized Loss Positions, Qualitative Disclosure, Number Of Positions, Before Reclassification To Disposal Group, Assets Held For Sale Amount by which credit facilty term length can be increased Debt Instrument Term Additional Amount by which Company may increase the term length of the credit agreement. Account value Net Amount at Risk by Product and Guarantee, General Account Value Entity Address, Address Line One Entity Address, Address Line One Entity Emerging Growth Company Entity Emerging Growth Company Unrealized Appreciation Available For Sale Securities Accumulated Gross Unrealized Gain Before Tax Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Accumulated Gross Unrealized Gain Before Tax Before Reclassification To Disposal Group Assets Held For Sale Berkshire Berkshire Berkshire Hathway Life Insurance Company Of Nebraska [Member] Berkshire Hathway Life Insurance Company Of Nebraska Other Other Pharmacy [Member] Various Other Variable Interest Entities Various Other Financial Instruments [Member] Various Other Financial Instruments Amortized Cost Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Amortized Cost Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Amortized Cost Before Reclassification To Disposal Group Assets Held For Sale $1,248 million, 4.75% Notes due 2021 Notes Due 2021, 4.75% Interest [Member] Senior notes payable bearing interest at 4.75% due in 2021. Debt assumed acquisition from Express Scripts. Net income Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Total reinsurance recoveries Policyholder Benefits and Claims Incurred, Ceded Maximum Maximum [Member] Other Non- controlling Interests Noncontrolling Interest [Member] Insurance customer receivables Insurance Customer Receivables Receivables due from customers under insurance contracts. Common dividends declared Dividends, Common Stock, Cash Unfunded commitments Unfunded Commitments Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments Incurred costs related to: Incurred claims related to: Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract] Comprehensive income (loss) attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest [Abstract] Consolidated effective tax rate Effective Income Tax Rate Reconciliation, Percent Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] $1,500 million, 2.4% Notes due 2030 Notes Due 2030, 2.4% Interest [Member] Notes Due 2030, 2.4% Interest Investments [Domain] Investments [Domain] Trading Symbol Trading Symbol Shares: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Disposal Group Classification [Domain] Disposal Group Classification [Domain] GMDB Guaranteed Minimum Death Benefit [Member] Foreign currency Liability for Unpaid Claims and Claims Adjustment Expense, Foreign Currency Translation Gain (Loss) Future policy benefits Liability For Future Policy Benefits Including Disposal Groups Liability For Future Policy Benefits Including Disposal Groups Fair value of collateral posted Derivative, Collateral, Right to Reclaim Securities Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Summary of Insurance and Contractholder Liabilities, Activity in the Unpaid Claims Liability and Liability Details for Unpaid Claims and Claim Expenses Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block] Entity Shell Company Entity Shell Company After-tax Special Items After Tax [Abstract] Equity securities with no readily determinable fair value Equity Securities Without Readily Determinable Fair Value, Amortized Cost, Before Reclassification To Disposal Group, Assets Held For Sale Equity Securities Without Readily Determinable Fair Value, Amortized Cost, Before Reclassification To Disposal Group, Assets Held For Sale Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Purchases, sales and settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Recurring Fair Value, Recurring [Member] Net Amount at Risk, by Product and Guarantee [Table] Net Amount at Risk, by Product and Guarantee [Table] Segment Information Segment Reporting, Policy [Policy Text Block] Transfers into Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Long-Term Investments Long-Term Investments [Member] Long-Term Investments Amortized Cost Equity Securities, FV-NI And Without Readily Determinable Fair Value, And Hybrid Instruments, Amortized Cost [Abstract] Equity Securities, FV-NI And Without Readily Determinable Fair Value, And Hybrid Instruments, Amortized Cost Noncatastrophic Event [Axis] Noncatastrophic Event [Axis] Document Type Document Type International Markets International Markets [Member] International Markets includes supplemental health, life and accident insurance products and health care coverage in our international markets as well as health care benefits to globally mobile employees of multinational organizations. Favorable (unfavorable) variance, percentage Liability For Unpaid Medical Claims And Claims Adjustment Expense Incurred Claims Prior Years Percentage Amount of payments made in the reporting period to settle claims incurred in prior periods and related claims settlement costs as a percentage of incurred claims as reported in the prior year. Interest expense and other Other Nonoperating Income (Expense) Non-current insurance and contractholder liabilities Total insurance and contractholder liabilities Insurance And Contractholder Liabilities Noncurrent The carrying amounts as of the balance sheet date of all current insurance and contractholder liabilities. Commitments And Contingencies [Line Items] Commitments And Contingencies [Line Items] Commitments And Contingencies Unpaid claims and claim expenses Beginning balance Ending balance Liability for Claims and Claims Adjustment Expense Treasury Stock Treasury Stock [Member] Proceeds related to legal claim Proceeds from Legal Settlements Realized investment losses on assets measured at fair value under certain conditions, after-tax Realized Investment Losses Commercial Mortgage Loans And Real Estate Entities With No Readily Determinable Fair Value Realized investment losses on impaired real estate, partnership entities, commercial mortgage loans and certain equity securities with no readily determinable fair value, after-tax. Fees and other revenues Services Service [Member] Fair Value Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract] Segments [Axis] Segments [Axis] Total Fair Value Debt Securities, Available-For-Sale, Unrealized Loss Position, Before Reclassification To Disposal Group, Assets Held For Sale Debt Securities, Available-For-Sale, Unrealized Loss Position, Before Reclassification To Disposal Group, Assets Held For Sale Changes in the Components of AOCI Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Other long-term investments Other Long Term Investments Before Reclassification To Disposal Group Assets Held For Sale Other Long Term Investments Before Reclassification To Disposal Group Assets Held For Sale Prior years: Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims, Prior Years [Abstract] Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims, Prior Years Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Liability for Claims and Claims Adjustment Expense [Table] Liability for Claims and Claims Adjustment Expense [Table] Change in unrealized gains or losses included in other comprehensive income for assets held at the end of the reporting period Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Unrealized Gain (Loss) Included In Other Comprehensive Income (Loss) Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Unrealized Gain (Loss) Included In Other Comprehensive Income (Loss) Sales Information for Available-for-Sale Debt Securities Available For Sale Securities Sales Information Table [Table Text Block] Summarization of sales information required and determined to be disclosed concerning Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. Future policy benefits classified as liabilities of business held for sale Liability For Future Policy Benefits Attributable To Disposal Groups Liability For Future Policy Benefits Attributable To Disposal Groups Other Current Assets Other Current Assets [Member] 364-Day Term Loan 364-Day Term Loan [Member] 364-Day Term Loan GMIB recoverables Derivative Asset Transfers into/(out of) Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract] Effects of Reinsurance Effects of Reinsurance [Table Text Block] Line of Credit Line of Credit [Member] $900 million, 3.25% Notes due 2025 Notes Due 2025 3.25% Interest [Member] Notes payable bearing interest at 3.25% due in 2025. Deferred tax liabilities, net Deferred Income Tax Liabilities, Net Summary of Debt Issuances Schedule Of Issuances Of Long-Term Debt [Table Text Block] Schedule Of Issuances Of Long-Term Debt Other intangible assets Intangible Assets, Net (Excluding Goodwill) Ceded Credit Risk, Collateralization [Domain] Ceded Credit Risk, Collateralization [Domain] Balance Balance Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value Before Reclassification To Disposal Group Assets Held For Sale Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value Before Reclassification To Disposal Group Assets Held For Sale Accounts receivable Increase (Decrease) in Accounts and Other Receivables Income from operations Operating Income (Loss) Other, including finance leases Other Long-term Debt, Noncurrent Investments by Consolidated and Nonconsolidated Entities [Axis] Investments by Consolidated and Nonconsolidated Entities [Axis] Credit loss (expense) recoveries on invested assets Debt Securities, Available-For-Sale, And Commercial Mortgage Loans, Allowance For Credit Loss, Expense (Reversal) Debt Securities, Available-For-Sale, And Commercial Mortgage Loans, Allowance For Credit Loss, Expense (Reversal) Contingencies — Note 18 Commitments and Contingencies Repurchase of common stock Payments for Repurchase of Common Stock Entity Address, State or Province Entity Address, State or Province Liquidity Measurement Input, Liquidity [Member] Measurement Input, Liquidity Reinsurance Reinsurance Accounting Policy [Policy Text Block] Accounts payable Accounts Payable, Current Gains (losses) required to adjust future policy benefits for settlement annuities Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Required To Adjust Future Policy Benefits This element represents total gains or losses for the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in gains or losses required to adjust future policy benefits for settlement annuities. Unusual or Infrequent Item, or Both [Line Items] Unusual or Infrequent Item, or Both [Line Items] Proceeds from investments sold: Proceeds from Sale and Maturity of Debt Securities, Available-for-sale [Abstract] Retained earnings Retained Earnings (Accumulated Deficit) Domestic disability, life and accident premiums Disability Life Accident [Member] Operating lease ROU assets Operating Lease, Right-of-Use Asset Allowance for credit losses on reinsurance recoverables Allowance for uncollectible reinsurance Reinsurance Recoverable, Allowance for Credit Loss Debt extinguishment costs Debt extinguishment costs Loss on repurchase of debt, pre-tax Gain (Loss) on Extinguishment of Debt $3,000 million, 4.9% Notes due 2048 Notes Due 2048, 4.9% Interest [Member] Senior notes payable bearing interest at 4.9% due in 2048. Debt issued to finance acquisition. $277 million, 4% Notes due 2022 Notes due 2022 4% Interest [Member] Notes payable bearing interest at 4% due in 2022. Shareholders’ equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Fair Value Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value Before Reclassification To Disposal Group Assets Held For Sale Hedging Designation [Domain] Hedging Designation [Domain] Federal government and agency Federal government securities US Treasury and Government [Member] Roll-Forward of the Allowance for Credit Losses on Debt Securities Debt Securities, Available-for-sale, Allowance for Credit Loss [Table Text Block] Payments for debt extinguishment Payment for Debt Extinguishment or Debt Prepayment Cost Valuation Approach and Technique [Domain] Valuation Approach and Technique [Domain] Other segments All Other Segments Other Than Integrated Medical [Member] All segments other than Integrated Medical. EPS, effect of dilution (in dollars per share) Earnings Per Share Effect Of Dilution The decrease in net income (loss) on a per share basis when the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period is assumed. Other, net Payments for (Proceeds from) Other Investing Activities Unearned premiums Unearned Premiums Guaranty Fund Assessments Insurance-related Assessments [Member] Credit Rating, Nationally Recognized Statistical Rating Organization (NRSRO) [Axis] Credit Rating, Nationally Recognized Statistical Rating Organization (NRSRO) [Axis] Credit Rating, Nationally Recognized Statistical Rating Organization (NRSRO) Revenues Revenue from Contract with Customer, Excluding Assessed Tax Risk corridors recovery (Selling, general and administrative expenses) Special Item, Gain (Loss) On Risk Corridor Allowance Adjustment, Before Taxes Special Item, Gain (Loss) On Risk Corridor Allowance Adjustment, Before Taxes Gain Contingencies, Nature [Axis] Gain Contingencies, Nature [Axis] Investments Investment, Policy [Policy Text Block] Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) [Text Block] Disclousre of the changes in the componenets of other comprehensive income/loss. Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Axis] Deferred income tax (benefit) Increase (Decrease) in Deferred Income Taxes Shareholders’ net income per share Earnings Per Share, Basic and Diluted [Abstract] Number of limited partnerships defined as variable interest entities Variable Interest Entity Number Of Entities Number of individual variable interest entities associated with an aggregate disclosure. Favorable (unfavorable) impact of prior year development on pre-tax income Impact Of Prior Year Development On Pretax Income Net impact (unfavorable) of prior year development on pre-tax income Accounts payable and Accrued expenses and other liabilities Increase Decrease In Accounts Payable Accrued And Other Operating Liabilities The increase (decrease) during the reporting period in the aggregate amount of accounts payable, accrued liabilities and other operating obligations not separately disclosed in the statement of cash flows. Aggregate principal amount of outstanding debt securities repurchased under tender offer Debt Instrument, Repurchased Face Amount, Tender Offer Debt Instrument, Repurchased Face Amount, Tender Offer Reinsurance Reinsurance [Text Block] More than one year Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months Or Longer [Abstract] Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months Or Longer Credit Facility [Axis] Credit Facility [Axis] Due after one year through five years Available For Sale Securities Debt Maturities After One Through Five Years Fair Value Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Debt Maturities After One Through Five Years Fair Value Before Reclassification To Disposal Group Assets Held For Sale Summary of the Credit Risk Profile of the Commercial Mortgage Loan Portfolio Financing Receivable Credit Quality Indicators [Table Text Block] Net unrealized appreciation on securities and derivatives Other Comprehensive Income (Loss), Available-For-Sale Securities And Derivatives Adjustment, Net Of Tax Other Comprehensive Income (Loss), Available-For-Sale Securities And Derivatives Adjustment, Net Of Tax Medical cost trend Medical Cost Trend [Member] Amounts relating to actual claims emerging differently from assumptions about the level of claims per member used to set reserves. Restructuring and Related Activities [Abstract] Restructuring and Related Activities [Abstract] Beginning balance, net Ending balance, net Liability for Unpaid Claims and Claims Adjustment Expense, Net Business Combinations [Abstract] Business Combinations [Abstract] $973 million, 3.9% Notes due 2022 Notes Due 2022, 3.9% Interest [Member] Senior notes payable bearing interest at 3.9% due in 2022. Debt assumed acquisition from Express Scripts. Commercial Portfolio Segment Commercial Portfolio Segment [Member] Changes in Total Equity Increase (Decrease) in Stockholders' Equity [Roll Forward] Real Estate Loan Real Estate Loan [Member] Investment maturities and repayments: Proceeds from Sale and Maturity of Held-to-maturity Securities [Abstract] Gain Contingency, Nature [Domain] Gain Contingency, Nature [Domain] Amount by which credit facilty amount can be increased Credit Facility Maximum Borrowing Capacity Additional Amount by which Company may increase its maximum borrowing capacity under credit agreement. Issuance of common stock Proceeds from Issuance of Common Stock Net proceeds Proceeds From Issuance Of Long-term Debt, Net Of Discounts And Underwriting Fees Proceeds From Issuance Of Long-term Debt, Net Of Discounts And Underwriting Fees Computation of Basic and Diluted Earnings Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Debt extinguishment costs (Debt extinguishment costs) Special Item Charges Debt Extinguishment Costs Net Of Tax Special Item Charges Debt Extinguishment Costs Net Of Tax Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Leases Lessee, Finance Leases [Text Block] Below investment grade Below Investment Grade [Member] External credit-ratings or internal groupings that could be used to describe the current status of the payment and performance risk of debt and securities investments that connote non-investment grade. Outstanding balances Long-term Line of Credit Reverse termination fee receivable Acquirer Merger Agreement Termination Fee Regulatory Approval Not Attained Merger agreement termination fee due from acquirer to the Company if regulatory approval is not attained or if closing does not occur by January 31, 2017 (subject to extension to April 30, 2017 under certain circumstances). Favorable (unfavorable) impact of prior year development on shareholders' net income Impact Of Prior Year Development On Shareholders Net Income Net impact (unfavorable) of prior year development on shareholders' net income. Other Other Investments [Member] NET CASH PROVIDED BY OPERATING ACTIVITIES  Net Cash Provided by (Used in) Operating Activities Prior years Favorable (unfavorable) variance, amount Prior Year Claims and Claims Adjustment Expense Entity Central Index Key Entity Central Index Key Securities and Derivatives AOCI, Accumulated Gain (Loss), Debt Securities, Available-For-Sale And Derivatives, Parent [Member] AOCI, Accumulated Gain (Loss), Debt Securities, Available-For-Sale And Derivatives, Parent Derivative Instrument [Axis] Derivative Instrument [Axis] Senior Notes Senior Notes [Member] Total benefits and expenses Benefits, Losses and Expenses Investments including assets of business held for sale Investments Before Reclassification To Disposal Group Assets Held For Sale Investments Before Reclassification To Disposal Group Assets Held For Sale Reclassification adjustment, tax Reclassification from AOCI, Current Period, Tax Segments [Domain] Segments [Domain] Fair Values of Separate Account Assets Fair Value Of Separate Account Assets [Table Text Block] Disclose the aggregate fair value of separate account assets, by fair value level. Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Other Other Commercial Medical Products [Member] Investments including assets of business held for sale Short Term Investments Before Reclassification To Disposal Group Assets Held For Sale Short Term Investments Before Reclassification To Disposal Group Assets Held For Sale Amounts included in shareholders net income for GMIB assets Total gains (losses) included in shareholders’ net income Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Total insurance and contractholder liabilities Insurance And Contractholder Liabilities Insurance And Contractholder Liabilities Due in one year or less Available For Sale Securities Debt Maturities Within One Year Amortized Cost Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Debt Maturities Within One Year Amortized Cost Before Reclassification To Disposal Group Assets Held For Sale Amortization of acquired intangible assets Amortization of acquired intangible assets Amortization of Intangible Assets Unpaid claims and claim expenses Beginning balance Ending balance Unpaid claims and claim expenses Liability For Claims And Claims Adjustment Expense Including Disposal Groups Liability For Claims And Claims Adjustment Expense Including Disposal Groups Investments classified as assets of business held for sale Disposal Group Including Discontinued Operation Investments Disposal Group Including Discontinued Operation Investments Segment Information Segment Reporting Disclosure [Text Block] Accounts receivable, net Accounts receivable, net per Consolidated Balance Sheets Receivables, Net, Current Integration and transaction-related costs, after-tax Integration and transaction-related costs (Selling, general and administrative expenses) Transaction Related Costs After Tax After-tax transaction-related costs including the impact of tax benefits realized from termination of merger agreement. Transaction-related costs consist primarily of fees for legal, advisory and other professional services as well as employee costs. Title of 12(b) Security Title of 12(b) Security Fair value of collateral contractually required to meet or exceed carrying value of recoverable Ceded Credit Risk, Secured, Contractually Required Fair Value [Member] Ceded Credit Risk, Secured, Contractually Required Fair Value Disposal Group Classification [Axis] Disposal Group Classification [Axis] Investments by Category Investment Holdings, Schedule of Investments [Table Text Block] Net Amount at Risk by Product and Guarantee [Line Items] Net Amount at Risk by Product and Guarantee [Line Items] Carrying Value Information for Other Long-Term Investments Schedule Of Other Long-Term Investments [Table Text Block] Schedule Of Other Long-Term Investments Total reinsurance recoverables Reinsurance Recoverables, Including Reinsurance Premium Paid Total impact from special items Special Item Gain Or Loss Before Tax Attributable To Reportng Entity Sum of before-tax tax amounts classified as special items, attributable to the parent. Special items are excluded from the calculation of 'adjusted income (loss) from operations' because management believes they are not representative of the underlying results of operations. This is generally because the nature and size of these matters are not indicative of our ongoing business operations. Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Abstract] Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Short-term investments Short-term Investments [Member] Gross Unrealized Appreciation (Depreciation) on Debt Securities Unrealized Gain (Loss) on Investments [Table Text Block] Requirements and Expected Effects of New Guidance Adopted and Not Yet Adopted Accounting Standards Update and Change in Accounting Principle [Table Text Block] Product and Service [Axis] Product and Service [Axis] Investment Type [Axis] Investment Type [Axis] Insurance [Abstract] Reclassification adjustment for amortization of net losses from past experience and prior service costs (interest expense and other) Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] Cash and cash equivalents Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents Other Assets Other Noncurrent Assets [Member] Net proceeds on issuance of term loan Proceeds from Notes Payable Valuation Approach and Technique [Axis] Valuation Approach and Technique [Axis] Carrying Value Financing Receivable, Before Allowance For Credit Loss, Before Reclassification To Disposal Group Assets Held For Sale Financing Receivable, Before Allowance For Credit Loss, Before Reclassification To Disposal Group Assets Held For Sale Expected liquidation period after inception Fair Value Investments Entities That Calculate Net Asset Value Per Share Liquidating Investment Period From Inception Expected liquidation period after inception of the underlying assets measured at net asset value per share or unit. Securities Limited Partnerships and Real Estate Limited Partnerships Securities Limited Partnerships And Real Estate Limited Partnerships [Member] Securities Limited Partnerships And Real Estate Limited Partnerships Unrealized Depreciation Available For Sale Securities Accumulated Gross Unrealized Loss Before Tax Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Accumulated Gross Unrealized Loss Before Tax Before Reclassification To Disposal Group Assets Held For Sale Shareholders’ net income Shareholders’ net income Net Income (Loss) Available to Common Stockholders, Basic Commercial mortgage loans Proceeds from Collection of Loans Receivable Liberty Re (Bermuda) Ltd. Liberty Mutual Insurance [Member] Liberty Mutual Insurance (Benefits) charges associated with litigation matters (Selling, general and administrative expenses) Special Item Charge After Tax Litigation After-tax charges associated with litigation matters that are classified as special items, attributable to the parent. Special items reflect amounts that management does not believe are representative of underlying results of operations. Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Allowance for credit losses on financing receivables Financing Receivable, Allowance for Credit Loss Other Other Government Products [Member] Gross gains on sales Debt Securities, Available-for-sale, Realized Gain Debt Instrument [Axis] Debt Instrument [Axis] Fair Value Hedging Fair Value Hedging [Member] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Operating Segments Operating Segments [Member] $1,500 Million, 2.40% Debt due March 15, 2030 2.40% Long-Term Debt Due March 15, 2030 [Member] 2.40% Long-Term Debt Due March 15, 2030 Repurchase of common stock Treasury Stock, Value, Acquired, Cost Method GMIB liabilities Derivative liabilities Derivative Liability 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] Litigation Case [Axis] Litigation Case [Axis] Assets maintained by employers (minimum) Guarantor Obligations, Liquidation Proceeds, Monetary Amount Total paid Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid Schedule of Investments [Line Items] Schedule of Investments [Line Items] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] (Income) attributable to noncontrolling interests Income Loss Attributable To Noncontrolling Interest Before Tax Amount of pre-tax income (loss) attributable to noncontrolling interest. Additional Damages Including Lost Premium Value To Shareholders Additional Damages, Including Lost Premium Value To Shareholders [Member] Additional Damages, Including Lost Premium Value To Shareholders Variable Interest Entities [Abstract] Variable Interest Entities [Abstract] Variable Interest Entity, Not Primary Beneficiary Variable Interest Entity, Not Primary Beneficiary [Member] Subsequent Event Subsequent Event [Member] Net income Temporary Equity, Net Income $500 million, 2.6% Notes due 11/2020 Notes Due 2020, 2.6% Interest [Member] Senior notes payable bearing interest at 2.6% due in 2020. Debt assumed acquisition from Express Scripts. Positive Outcome of Litigation Positive Outcome of Litigation [Member] Balance sheet location of non-current operating lease liabilities Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table] Fair Value Estimate of Fair Value Measurement [Member] Other non-current liabilities Operating Lease, Liability, Noncurrent Postretirement benefits liability adjustment Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Short-Term Investments and Cash Equivalents Cash, Cash Equivalents and Investments [Table Text Block] Total incurred Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims Securities Not Priced by the Company Unobservable Inputs Not Developed By Company [Member] Significant unobservable inputs used in pricing Level 3 securities that were not developed directly by the Company Allowance for Credit Loss Debt Securities, Available For Sale, Allowance For Credit Loss, Before Reclassification To Disposal Group Assets Held For Sale Debt Securities, Available For Sale, Allowance For Credit Loss, Before Reclassification To Disposal Group Assets Held For Sale Number of Issues Available For Sale Securities In Unrealized Loss Positions, Qualitative Disclosure, Less Than 12 Months, Number Of Positions, Before Reclassification To Disposal Group, Assets Held For Sale Available For Sale Securities In Unrealized Loss Positions, Qualitative Disclosure, Less Than 12 Months, Number Of Positions, Before Reclassification To Disposal Group, Assets Held For Sale Home delivery and specialty revenues Home Delivery And Specialty [Member] SHAREHOLDERS' COMPREHENSIVE INCOME Comprehensive Income (Loss), Net of Tax, Attributable to Parent Net amount at risk Net Amount at Risk by Product and Guarantee, Net Amount at Risk City Area Code City Area Code Document Period End Date Document Period End Date Percent of debt and equity securities classified in Level 3 Debt And Equity Securities Classified In Level 3 Percentage Before Reclassification To Disposal Group Assets Held For Sale Percent of debt and equity securities classified in Level 3 Total Separate Account Assets Before Reclassification To Disposal Group Assets Held For Sale Separate Account Assets Before Reclassification To Disposal Group Assets Held For Sale Equity Security Investments Equity Securities, FV-NI And Equity Securities Without Readily Determinable Fair Value [Table Text Block] Equity Securities, FV-NI And Equity Securities Without Readily Determinable Fair Value Net Investment Hedging Net Investment Hedging [Member] Other comprehensive income (loss), before reclassifications, before tax, including temporary equity Other Comprehensive Income (Loss), before Reclassifications, before Tax, Including Temporary Equity Other Comprehensive Income (Loss), before Reclassifications, before Tax, Including Temporary Equity Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net amounts reclassified from AOCI to net income Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Contractholder deposit funds Policyholder Contract Deposits Including Disposal Groups Policyholder Contract Deposits Including Disposal Groups Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Number of contractholders (estimated) Guaranteed Minimum Death Benefits Total Contractholders Total number of underlying contractholders for the Guaranteed Minimum Death Benefit business. Other receivables Accounts and Other Receivables, Net, Current Other comprehensive income (loss) before reclassifications, before tax Other Comprehensive Income (Loss), before Reclassifications, before Tax Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Health Insurance Medical Risk Products [Member] Other, net Proceeds from (Payments for) Other Financing Activities Contractholder deposit funds Policyholder Contract Deposit $750 million, 3.2% Notes due 2040 Notes Due 2040, 3.2% Interest [Member] Notes Due 2040, 3.2% Interest Cover [Abstract] Measurement Input Type [Axis] Measurement Input Type [Axis] $300 million, 5.125% Notes due 6/2020 Notes due 2020 5.125% Interest [Member] Notes payable bearing interest at 5.125% due in 2020. Contractholder Deposit Funds Contractholder Deposit Funds, Policy [Policy Text Block] Describes an entity's accounting policy for contractholder deposit funds. Other comprehensive income (loss) before reclassifications, after-tax Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Accrued expenses and other liabilities Accrued Expenses And Other Liabilities Carrying value as of the balance sheet date of other current liabilities and obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). GMIB Assets Guaranteed Minimum Income Benefits Assets [Member] Retrocessional coverage purchased for reinsured contracts with issuers of GMIB products. $17 million, 8.3% Notes due 2023 Notes Due 2023, 8.3% Interest [Member] Notes payable bearing interest at 8.3% due in 2023. Leases Lessee, Operating Leases [Text Block] Total Short-Term And Long-Term Investments [Abstract] Short-Term And Long-Term Investments Carrying Value Equity Securities, FV-NI And Without Readily Determinable Fair Value, And Hybrid Instruments, Carrying Amount, Before Reclassification To Disposal Group, Assets Held For Sale [Abstract] Equity Securities, FV-NI And Without Readily Determinable Fair Value, And Hybrid Instruments, Carrying Amount, Before Reclassification To Disposal Group, Assets Held For Sale Investments per Consolidated Balance Sheets Investments Debt securities Debt Securities [Member] Percent of debt and equity securities classified in Level 2 Debt And Equity Securities Classified In Level 2 Percentage Before Reclassification To Disposal Group Assets Held For Sale Percent of debt and equity securities classified in Level 2 Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Pharmacy and other service costs Cost of Goods and Services Sold Sun Life Assurance Company of Canada Sun Life Assurance Company Of Canada [Member] Sun Life Assurance Company of Canada Gain (loss) recognized in other comprehensive income Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Equity Components [Axis] Equity Components [Axis] $250 million, 4.375% Notes due 12/2020 Notes Due 2020, 4.375% Interest [Member] Notes payable bearing interest at 4.375% due in 2020. Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Minimum Minimum [Member] Securities partnerships Securities partnerships Partnership Interest [Member] Receivables [Abstract] Receivables [Abstract] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other comprehensive income (loss) before reclassifications, tax, including temporary equity Other Comprehensive Income (Loss) before Reclassifications, Tax, Including Temporary Equity Other Comprehensive Income (Loss) before Reclassifications, Tax, Including Temporary Equity Separate Account Assets Separate Account Assets [Member] A separate investment account established and maintained by an insurance entity under relevant state insurance law to which funds have been allocated for certain contracts of the insurance entity. Funds in a separate account are not commingled with other assets of the insurance entity for investment purposes. Property and equipment Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization Total Equity Securities, FV-NI And Without Readily Determinable Fair Value, And Hybrid Instruments, Carrying Amount Equity Securities, FV-NI And Without Readily Determinable Fair Value, And Hybrid Instruments, Carrying Amount $300 million, 4.5% Notes due 2021 Notes Due 2021 4.5% Interest [Member] Notes payable bearing interest at 4.5% due in 2021. Less: Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest $349 million, 4.125% Notes due 9/2020 Notes Due 2020, 4.125% Interest [Member] Senior notes payable bearing interest at 4.125% due in 2020. Debt assumed acquisition from Express Scripts. Total ceded premiums Ceded Premiums Earned Property and equipment purchases, net Payments For (Proceeds From) Property, Plant, And Equipment Payments For (Proceeds From) Property, Plant, And Equipment Mortgage and other asset-backed Mortgage and other asset-backed securities Other Asset-Backed and Corporate Securities Asset-backed Securities [Member] Entity Interactive Data Current Entity Interactive Data Current Revenues Revenues [Abstract] Contractholder deposit funds classified as liabilities of business held for sale Policyholder Contract Deposits Attributable To Disposal Groups Policyholder Contract Deposits Attributable To Disposal Groups Summary of Debt Securities with a Decline in Fair Value Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table Text Block] $259 million, 7.875% Debentures due 2027 Debentures due 2027 7.875% Interest [Member] Debentures bearing interest at 7.875% due in 2027. Unusual or Infrequent Item, or Both [Axis] Unusual or Infrequent Item, or Both [Axis] Other assets Disposal Group, Including Discontinued Operation, Other Assets, Current Derivative [Table] Derivative [Table] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Total transfers into/(out of) Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net Schedule of Investments [Table] Schedule of Investments [Table] Outstanding Amounts of Debt and Finance Leases Schedule Of Short Term Debt Long Term Debt [Table Text Block] A table or schedule providing information pertaining to borrowings under which repayment was required in less than twelve months (or normal operating cycle, if longer) after its issuance. It may include: (1) description of the short-term debt arrangement; (2) identification of the lender or type of lender; (3) repayment terms; (4) weighted average interest rate; (5) carrying amount of funds borrowed under the specified short-term debt arrangement as of the balance-sheet date and measures of the maximum and average amount outstanding during the period; (6) description of the refinancing of a short-term obligation when that obligation is excluded from current liabilities in the balance sheet; and (7) amount of a short-term obligation that has been excluded from current liabilities in the balance sheet because of a refinancing of the obligation. Also, Pertinent information about each long-term debt arrangement including the carrying amount as of the balance sheet date, by type of long-term debt. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the company, if longer. Revenue contribution from transitioning clients Revenue Transitioning Clients Adjustment to exclude revenue from transitioning clients from ajusted revenues. Retirement Plan Type [Domain] Retirement Plan Type [Domain] Fair value of off-balance-sheet financial assets Fair Value Disclosure, Off-balance Sheet Risks, Amount, Asset $1,000 million, Floating Rate Notes due 3/2020 Notes Due 2020, Floating Rate Interest [Member] Senior notes payable with floating interest due in 2020. Debt issued to finance acquisition. Unpaid claims and claim expenses Liability For Claims And Claims Adjustment Expense Noncurrent Including Disposal Groups The amount (expected to be paid after one year) needed to reflect the estimated ultimate cost of settling claims relating to insured events that have occurred on or before the balance sheet date, whether or not reported to the insurer at that date. Debt securities and equity securities Proceeds From Maturities Prepayments And Calls Of Debt And Equity Securities Proceeds from maturities, repayments and calls of debt and equity securities. Net investment income Net investment income Net Investment Income Consolidation Items [Axis] Consolidation Items [Axis] Weighted average (in shares) Weighted Average Number of Shares Issued, Basic Other (primarily short-term and other long-term investments) Payments to Acquire Other Investments Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Group Disability and Life Group Disability And Life [Member] Assets Held for Sale Disposal Group, Including Discontinued Operation, Assets [Member] Disposal Group, Including Discontinued Operation, Assets Deferred policy acquisition costs Deferred Policy Acquisition Cost Guaranteed Insurance Contract, Type of Benefit [Axis] Guaranteed Insurance Contract, Type of Benefit [Axis] Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] Commercial mortgage loans Payments to Acquire Mortgage Notes Receivable Effects of Reinsurance [Line Items] Effects of Reinsurance [Line Items] Current insurance and contractholder liabilities Total insurance and contractholder liabilities Insurance And Contractholder Liabilities Current The carrying amounts as of the balance sheet date of all current insurance and contractholder liabilities. Document Transition Report Document Transition Report Run-Off Settlement Annuity Business Runoff Settlement Annuity Business [Member] Represents information pertaining to the settlement annuity business, a closed run-off block of single premium annuity contracts, reported under the Other Operations segment. Contractholder deposit funds Policyholder Contract Deposits Current Including Disposal Groups The liability as of the balance sheet date to the policyholders for deposits held under the terms of insurance contracts, expected to be paid within one year. Risk corridors recovery (Selling, general and administrative expenses) Special Item, Gain (Loss) On Risk Corridor Allowance Adjustment, Net Of Tax Special Item, Gain (Loss) On Risk Corridor Allowance Adjustment, Net Of Tax Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Equity securities with readily determinable fair values Equity Securities Fv Ni Cost Before Reclassification To Disposal Group Assets Held For Sale Equity Securities Fv Ni Cost Before Reclassification To Disposal Group Assets Held For Sale Sale price Disposal Group, Including Discontinued Operation, Consideration Prior years Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years Document Quarterly Report Document Quarterly Report Financial liabilities at fair value Liabilities, Fair Value Disclosure [Abstract] Total Insurance And Contractholder Liabilities, Current, Including Disposal Groups Insurance And Contractholder Liabilities, Current, Including Disposal Groups Other comprehensive (loss) attributable to redeemable noncontrolling interest Other comprehensive income (loss) Less: Net translation of foreign currencies attributable to noncontrolling interests Temporary Equity Other Comprehensive Income The portion of other comprehensive income or(loss) attributable to temporary equity interest. Financial Guarantee Financial Guarantee [Member] All other incurred Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense Less Interest Accretion Amount, after effects of reinsurance and interest accretion recognized for short-duration contracts, of expense (reversal of expense) for claims incurred in prior reporting periods and related claims settlement costs. Cumulative Effect, Period Of Adoption [Axis] Cumulative Effect, Period of Adoption [Axis] Credit Facility [Domain] Credit Facility [Domain] Litigation Case [Domain] Litigation Case [Domain] Basic (in dollars per share) EPS, basic (in dollars per share) Earnings Per Share, Basic Entity File Number Entity File Number Cash Flows from Operating Activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Indemnification Agreement Indemnification Agreement [Member] Investments Disposal Group, Including Discontinued Operation, Investments, Current Disposal Group, Including Discontinued Operation, Investments, Current Assets and Liabilities Held for Sale Disposal Groups, Including Discontinued Operations [Table Text Block] Balance Sheet Location [Axis] Balance Sheet Location [Axis] One year or less Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less Than 12 Months [Abstract] Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less Than 12 Months U.S. Medical Integrated Medical [Member] Integrated Medical offers a variety of medical solutions to employers and individuals. The Commercial operating segment serves employers (also referred to as clients) and their employees (also referred to as customers) and other groups. This segment provides deeply integrated medical and specialty offerings including medical, pharmacy, dental, behavioral health and vision, health advocacy programs and other products and services to insured and self-insured customers. The Government operating segment offers Medicare Advantage, Medicare Supplement, and Medicare Part D plans to Medicare-eligible beneficiaries as well as Medicaid plans. This operating segment also offers health insurance coverage to individual customers both on and off the public exchanges. This segment includes the acquired Express Scripts Medicare Part D business. Disposal Group Name [Axis] Disposal Group Name [Axis] Prudential Retirement Insurance and Annuity Prudential Retirement Insurance And Annuity Company [Member] Reinsurance recoverables resulting from the 2004 sale of the Companys retirement benefits business, which was primarily in the form of a reinsurance arrangement. Commercial Paper Commercial Paper [Member] Accounts Receivable, Net Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Non-guaranteed separate accounts, including disposal groups Non Guaranteed Separate Account Assets Classified In Fair Value Hierarchy Before Reclassification To Disposal Group Assets Held For Sale Non Guaranteed Separate Account Assets Classified In Fair Value Hierarchy Before Reclassification To Disposal Group Assets Held For Sale Debt and Equity Securities Debt and Equity Securities [Member] Subtotal of debt and equity securities carried at fair value on the balance sheet. Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Other noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest Group Disability and Other Group Disability and Other [Member] $2,200 million, 4.8% Notes due 2038 Notes Due 2038, 4.8% Interest [Member] Senior notes payable bearing interest at 4.8% due in 2038. Debt issued to finance acquisition. Cash Flows from Investing Activities Net Cash Provided by (Used in) Investing Activities [Abstract] Balance Balance Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests Revenue from External Customers by Products and Services [Table] Revenue from External Customers by Products and Services [Table] Foreign currency forward contracts Foreign Exchange Forward [Member] Due after five years through ten years Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost Before Reclassification To Disposal Group Assets Held For Sale Total impact from special items Special Item Gain Or Loss Net Of Tax Attributable To Reportng Entity Sum of after-tax amounts classified as special items, attributable to the parent. Special items are excluded from the calculation of 'adjusted income (loss) from operations' because management believes they are not representative of the underlying results of operations. This is generally because the nature and size of these matters are not indicative of our ongoing business operations. 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] Litigation Status [Axis] Litigation Status [Axis] Operating leases: Assets And Liabilities, Lessee, Operating Leases [Abstract] Assets And Liabilities, Lessee, Operating Leases Amounts excluded from assessment of hedge effectiveness Gain (Loss) from Components Excluded from Assessment of Cash Flow Hedge Effectiveness, Net Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Liabilities of business held for sale Total liabilities of business held for sale Disposal Group, Including Discontinued Operation, Liabilities, Current Investment grade Investment Grade [Member] External credit-ratings or internal groupings that could be used to describe the current status of the payment and performance risk of debt and securities investments that connote investment grade. Amortized Cost Amortized Cost Available For Sale Debt Securities Amortized Cost Basis Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Debt Securities Amortized Cost Basis Before Reclassification To Disposal Group Assets Held For Sale Total liabilities and equity Liabilities and Equity Additions for debt securities where no credit loss has previously been recognized Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded Loss Contingencies [Line Items] Loss Contingencies [Line Items] Leverage ratio covenant Line Of Credit Facility Debt To Adjusted Capital Ratio Covenant The debt-to adjusted capital ratio which the Company must not exceed in accordance with the terms of the line of credit facility agreement. Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Income Taxes Income Tax Disclosure [Text Block] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Notes issued by Express Scripts, Medco and Old Cigna exchanged for Notes issued by Cigna Subsidiary Debt Exchanged For New Debt Issued By Parent Subsidiary Debt Exchanged For New Debt Issued By Parent Collateral provisions exist that may mitigate risk of credit loss Ceded Credit Risk, Secured, Collateral Provisions Exist That May Mitigate Risk [Member] Ceded Credit Risk, Secured, Collateral Provisions Exist That May Mitigate Risk Hedging Relationship [Axis] Hedging Relationship [Axis] Contractual adjustment for a former client (Pharmacy revenues) Contractual adjustment for a former client Special Item, Gain (Loss) From Contract Adjustment, Before Taxes Special Item, Gain (Loss) From Contract Adjustment, Before Taxes Antidilutive options (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Balance sheet location of non-current finance lease liabilities Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List] Stop loss Stop Loss [Member] An insurance product that provides additional coverage on Administrative Services Only plans that provides reimbursement for claims in excess of a predetermined amount. Retiree and Life Insurance Benefits Retirement And Life Insurance Contracts [Member] $500 million, 3.3% Notes due 2021 Notes Due 2021, 3.3% Interest [Member] Senior notes payable bearing interest at 3.3% due in 2021. Debt assumed acquisition from Express Scripts. Equity Component [Domain] Equity Component [Domain] Due in one year or less Available For Sale Securities Debt Maturities Within One Year Fair Value Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Debt Maturities Within One Year Fair Value Before Reclassification To Disposal Group Assets Held For Sale Insurance Loss Reserves [Abstract] Insurance Loss Reserves [Abstract] Additional Information on Separate Account Assets Priced at NAV Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table Text Block] Changes in Level 3 Financial Assets and Financial Liabilities Carried at Fair Value Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Table Text Block] Tabular disclosure of the fair value measurement of assets and liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and gains or losses recognized in other comprehensive income (loss) and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3, by class of assets and liabilities. Entity Tax Identification Number Entity Tax Identification Number Hedge funds Hedge Funds [Member] Pre-tax adjustments to reconcile to adjusted income from operations Pretax Adjustments To Reconcile Adjusted Income From Operations [Abstract] Current Insurance And Contractholder Liabilities, Current [Abstract] Insurance And Contractholder Liabilities, Current Net changes in assets and liabilities, net of non-operating effects: Increase (Decrease) in Operating Capital [Abstract] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Carrying values Net Assets Collectibility of CSRs Collectibility of Cost-Sharing Reduction (CSR) Receivable [Member] Collectibility of Cost-Sharing Reduction (CSR) Receivable Current Fiscal Year End Date Current Fiscal Year End Date Total Amortized Cost Debt Securities, Available-For-Sale, Unrealized Loss Position, Amortized Cost, Before Reclassification To Disposal Group, Assets Held-For-Sale Debt Securities, Available-For-Sale, Unrealized Loss Position, Amortized Cost, Before Reclassification To Disposal Group, Assets Held-For-Sale Total finance lease liabilities Finance Lease, Liability Maximum percentage of investments classified in Level 2 representing foreign bonds priced using unadjusted broker quotes Maximum Percent Level 2 Investments Foreign Bonds Broker Quote Before Reclassification To Disposal Group Assets Held For Sale Maximum percentage of Level 2 investments representing foreign bonds priced using a single unadjusted market-observable input derived by averaging multiple broker-dealer quotes. $500 million, 3.05% Notes due 2022 Notes Due 2022, 3.05% Interest [Member] Senior notes payable bearing interest at 3.05% due in 2022. Debt assumed acquisition from Express Scripts. Accumulated depreciation Finance Lease, Right-of-Use Asset, Accumulated Amortization Realized gains (losses) on investments still held at the reporting date Realized Investment Gain Loss Instruments Still Held At Reporting Date The net realized gains or (losses) on investments during the period `and still held at the reporting date, including gains (losses) on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity. Insurance and Contractholder Liabilities [Line Items] Insurance and Contractholder Liabilities [Line Items] Assets measured at fair value under certain conditions as a percent of total investments Assets Measured At Fair Value Under Certain Conditions Percent Of Total Investments Impaired real estate, partnership entities and commercial mortgage loans and certain equity securities with no readily determinable fair value that are impaired or have observable price changes as a percent of total investments. Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] Financing Receivable, Credit Quality Indicator [Table] Financing Receivable, Credit Quality Indicator [Table] $750 Million, 3.20% Debt due March 15, 2040 3.20% Long-Term Debt Due March 15, 2040 [Member] 3.20% Long-Term Debt Due March 15, 2040 Supplemental Disclosure of Cash Information: Supplemental Cash Flow Information [Abstract] $1,500 million, 4.5% Notes due 2026 Notes Due 2026, 4.5% Interest [Member] Senior notes payable bearing interest at 4.5% due in 2026. Debt assumed acquisition from Express Scripts. Net change in short-term debt Proceeds From (Repayments Of) Other Short-Term Debt Proceeds From (Repayments Of) Other Short-Term Debt Fair value of off-balance-sheet financial liabilities Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability Net income attributable to redeemable noncontrolling interest Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Ceded Credit Risk, Reinsurer [Domain] Ceded Credit Risk, Reinsurer [Domain] Short-term investments Other Short Term Investments Before Reclassification To Disposal Group Assets Held For Sale Other Short Term Investments Before Reclassification To Disposal Group Assets Held For Sale Adjustment for transitioning clients Income Loss Attributable To Transitioning Clients Pretax Pre-tax income from transitioning clients. Annuitization election period Annuitization Election Period The period of time prior to a policy anniversary when an annuitization election must occur. Equity securities with no readily determinable fair value Equity Securities Without Readily Determinable Fair Value Amount Before Reclassification To Disposal Group Assets Held For Sale Equity Securities Without Readily Determinable Fair Value Amount Before Reclassification To Disposal Group Assets Held For Sale Variable Annuity Variable Annuity [Member] Money market funds Money Market Funds [Member] Net realized investments (gains) losses Realized Investment Gain Loss Including Equity Method Subsidiaries The net realized gains or (losses) on investments during the period, including gains (losses) on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity. Includes gains (losses) on investments held by equity method subsidiaries. Property and equipment, net Finance Lease, Right-of-Use Asset, after Accumulated Amortization Gains (losses) included in other comprehensive income Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) Hedging Relationship [Domain] Hedging Relationship [Domain] Real estate funds Real Estate Funds [Member] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Non-current Insurance And Contractholder Liabilities, Noncurrent [Abstract] Insurance And Contractholder Liabilities, Noncurrent Change in Redeemable Noncontrolling Interests Increase (Decrease) in Temporary Equity [Roll Forward] Variable Interest Entities Consolidation, Variable Interest Entity, Policy [Policy Text Block] Loss Contingencies [Table] Loss Contingencies [Table] Carrying Value Reported Value Measurement [Member] Corporate and Eliminations Corporate And Eliminations [Member] Reflects amounts not allocated to other segments, such as net interest expense (defined as interest on corporate debt less net investment income on investments not supporting segment operations), interest on uncertain tax positions, certain litigation matters, intersegment eliminations, compensation cost for stock options, expense associated with its frozen pension plans, certain corporate project and overhead costs. $448 million, 6.125% Notes due 2041 Notes Due 2041, 6.125% Interest [Member] Senior notes payable bearing interest at 6.125% due in 2041. Debt assumed acquisition from Express Scripts. Pre-tax adjusted income (loss) from operations Adjusted Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest Total Insurance And Contractholder Liabilities, Including Disposal Groups Insurance And Contractholder Liabilities, Including Disposal Groups Long-term debt, including current maturities, excluding finance leases Long-term Debt, Fair Value Transfers out of Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 Unrealized Depreciation Available For Sale Securities Continuous Unrealized Loss Position 12 Months Or Longer Accumulated Loss Before Reclassification To Disposal Group Assets Held For Sale Available For Sale Securities Continuous Unrealized Loss Position 12 Months Or Longer Accumulated Loss Before Reclassification To Disposal Group Assets Held For Sale Total income taxes Income Tax Expense (Benefit) Cash, cash equivalents, and restricted cash September 30, per Consolidated Balance Sheets Total cash, cash equivalents, and restricted cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Weighting of credit spreads Measurement Input, Credit Spread [Member] Debt Securities, Available-for-sale [Table] Debt Securities, Available-for-sale [Table] Beginning balance, net Ending balance, net Liability For Unpaid Claims And Claims Adjustment Expense Net Including Disposal Groups Liability For Unpaid Claims And Claims Adjustment Expense Net Including Disposal Groups Short-term debt Finance Lease, Liability, Current Local Phone Number Local Phone Number $1,400 million, Floating Rate Term Loan due 3/2021 Notes Due March 1, 2021, Floating Rate Interest [Member] Notes Due March 1, 2021, Floating Rate Interest Reclassification adjustment, before tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Cumulative Effect, Period Of Adoption [Domain] Cumulative Effect, Period of Adoption [Domain] Derivative [Line Items] Derivative [Line Items] Unobservable Adjustment Debt Securities, Available-For-Sale, Including Disposal Group, Measurement Input Debt Securities, Available-For-Sale, Including Disposal Group, Measurement Input Unusual or Infrequent Item, or Both [Table] Unusual or Infrequent Item, or Both [Table] Withdrawals and benefit payments from contractholder deposit funds Withdrawal from Contract Holders Funds Investments classified as assets of business held for sale Disposal Group Including Discontinued Operation Noncurrent Investments Current Disposal Group Including Discontinued Operation Noncurrent Investments Number of participating banks Number Of Banks Participating In Revolving Credit And Letter Of Credit Agreement Number of banks participating in revolving credit and letter of credit agreement Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Adjustment for credit risk on derivatives liabilities Derivative Credit Risk Valuation Adjustment, Derivative Liabilities Fees Service, Fees [Member] Service, Fees Class of Financing Receivable [Axis] Class of Financing Receivable [Axis] Commercial paper Commercial Paper COVID-19 and Related Economic Impact Unusual or Infrequent Items, or Both, Disclosure [Text Block] Retained Earnings Retained Earnings [Member] Measurement Basis [Axis] Measurement Basis [Axis] Pharmaceutical manufacturers receivable Pharmaceutical Manufacturer Receivable Receivables due from pharmaceutical manufacturers related to rebate contracts. CSR Litigation with the Federal Government CSR Litigation With The Federal Government [Member] CSR Litigation With The Federal Government Balance sheet location of current finance lease liabilities Finance Lease, Liability, Current, Statement of Financial Position [Extensible List] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] Other external revenues Service, Other [Member] Unearned premiums, current Unearned Premiums Current Including Disposal Groups Carrying amount of premiums written on insurance contracts that have not been earned as of the balance sheet date, expected to be paid in one year. Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] NET CASH (USED IN) INVESTING ACTIVITIES  Net Cash Provided by (Used in) Investing Activities Hybrid equity securities Equity Securities, Hybrid Instruments, Carrying Amount, Before Reclassification To Disposal Group, Assets Held For Sale Equity Securities, Hybrid Instruments, Carrying Amount, Before Reclassification To Disposal Group, Assets Held For Sale Pending Litigation Pending Litigation [Member] Network revenues Network Pharmacy [Member] Liability for guarantees Guarantor Obligations, Current Carrying Value Corporate Corporate securities Corporate Debt Securities [Member] Discontinued Operations and Disposal Groups [Abstract] Litigation Status [Domain] Litigation Status [Domain] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] $700 million, Floating Rate Notes due 2023 Notes Due 2023 Floating Rate Interest [Member] Senior notes payable with floating interest due in 2023. Debt issued to finance acquisition. No collateral Ceded Credit Risk, Unsecured [Member] Less: treasury stock, at cost Treasury Stock, Value Pension Plan Pension Plan [Member] Earnings Per Share Earnings Per Share [Text Block] Summary of Special Items Schedule Of Special Items [Table Text Block] Schedule of pre- and after-tax amounts reported as special items, attributable to the parent. Special items are amounts that management does not believe are representative of underlying results of operations. Redeemable noncontrolling interests Redeemable Noncontrolling Interest, Equity, Carrying Amount Cash Flows from Financing Activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Finance leases: Assets And Liabilities, Lessee, Finance Leases [Abstract] Assets And Liabilities, Lessee, Finance Leases Premiums Premiums Earned, Net Recent Accounting Pronouncements, Recently Adopted Accounting Guidance and Accounting Guidance Not Yet Adopted New Accounting Pronouncements, Policy [Policy Text Block] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Investments Investments per Consolidated Balance Sheets Short-term Investments