Elevance Health (ELV) 10-Q 23 Oct 19 2019 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information Document - shares	9 Months Ended
	Sep. 30, 2019	Oct. 16, 2019
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001156039
Entity File Number	001-16751
Entity Registrant Name	ANTHEM, INC.
Entity Incorporation, State or Country Code	IN
Entity Tax Identification Number	35-2145715
Entity Address, Address Line One	220 Virginia Avenue
Entity Address, City or Town	Indianapolis
Entity Address, State or Province	IN
Entity Address, Postal Zip Code	46204
City Area Code	800
Local Phone Number	331-1476
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	ANTM
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Interactive Data Current	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		253,563,697

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 4,190	$ 3,934
Fixed maturity securities, current (amortized cost of $19,267 and $16,894)	19,960	16,692
Equity securities, current	2,300	1,493
Other invested assets, current	10	21
Accrued investment income	168	162
Premium receivables	4,782	4,465
Self-funded receivables	2,555	2,278
Other receivables	2,870	2,558
Income taxes receivable	91	10
Securities lending collateral	465	604
Other current assets	2,113	2,104
Total current assets	39,504	34,321
Long-term investments:
Fixed maturity securities (amortized cost of $500 and $486)	518	487
Equity securities	29	33
Other invested assets	3,914	3,726
Property and equipment, net	2,921	2,735
Goodwill	20,500	20,504
Other intangible assets	8,756	9,007
Other noncurrent assets	1,667	758
Total assets	77,809	71,571
Policy Liabilities
Medical claims payable	8,977	7,454
Reserves for future policy benefits	77	75
Other policyholder liabilities	2,503	2,590
Total policy liabilities	11,557	10,119
Unearned income	948	902
Accounts payable and accrued expenses	4,445	4,959
Security trades pending payable	542	197
Securities lending payable	465	604
Short-term borrowings	710	1,145
Current portion of long-term debt	700	849
Other current liabilities	3,867	3,190
Total current liabilities	23,234	21,965
Long-term debt, less current portion	18,820	17,217
Reserves for future policy benefits, noncurrent	661	706
Deferred tax liabilities, net	2,140	1,960
Other noncurrent liabilities	1,622	1,182
Total liabilities	46,477	43,030
Commitment and contingencies – Note 11
Shareholders' equity
Preferred stock, without par value, shares authorized – 100,000,000; shares issued and outstanding – none	0	0
Common stock, par value $0.01, shares authorized – 900,000,000; shares issued and outstanding – 253,780,229 and 257,395,577	3	3
Additional paid-in capital	9,524	9,536
Retained earnings	22,104	19,988
Accumulated other comprehensive loss	(299)	(986)
Total shareholders' equity	31,332	28,541
Total liabilities and shareholders' equity	$ 77,809	$ 71,571

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Available-for-sale fixed maturity securities investments, current, amortized cost	$ 19,267	$ 16,894
Available-for-sale fixed maturity securities investments, long-term, amortized cost	$ 500	$ 486
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	900,000,000	900,000,000
Common stock, shares issued	253,780,229	257,395,577
Common stock, shares outstanding	253,780,229	257,395,577

Consolidated Statements Of Inco

Consolidated Statements Of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues
Premiums	$ 23,793	$ 21,451	$ 70,137	$ 63,602
Administrative fees and other revenue	2,651	1,529	5,872	4,435
Total operating revenue	26,444	22,980	76,009	68,037
Net investment income	242	250	737	708
Net realized gains on financial instruments	1	27	90	5
Other-than-temporary impairment losses on investments:
Total other-than-temporary impairment losses on investments	(14)	(8)	(36)	(20)
Portion of other-than-temporary impairment losses recognized in other comprehensive income	1	2	6	2
Other-than-temporary impairment losses recognized in income	(13)	(6)	(30)	(18)
Total revenues	26,674	23,251	76,806	68,732
Expenses
Benefit expense	20,753	18,185	60,403	52,959
Cost of products sold	745	0	843	0
Selling, general and administrative expense	3,418	3,546	9,862	10,402
Interest expense	185	188	556	564
Amortization of other intangible assets	84	91	256	265
(Gain) loss on extinguishment of debt	0	(1)	(1)	17
Total expenses	25,185	22,009	71,919	64,207
Income before income tax expense	1,489	1,242	4,887	4,525
Income tax expense	306	282	1,014	1,200
Net income	$ 1,183	$ 960	$ 3,873	$ 3,325
Net income per share
Basic net income per share	$ 4.64	$ 3.70	$ 15.11	$ 12.89
Diluted net income per share	4.55	3.62	14.83	12.58
Dividends per share	$ 0.80	$ 0.75	$ 2.40	$ 2.25

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 1,183	$ 960	$ 3,873	$ 3,325
Other comprehensive income (loss), net of tax:
Change in net unrealized gains/losses on investments	116	(36)	711	(353)
Change in non-credit component of other-than-temporary impairment losses on investments	(1)	(2)	(2)	(2)
Change in net unrealized losses on cash flow hedges	(34)	2	(31)	34
Change in net periodic pension and postretirement costs	4	7	10	22
Foreign currency translation adjustments	(1)	0	(1)	0
Other comprehensive income (loss)	84	(29)	687	(299)
Total comprehensive income	$ 1,267	$ 931	$ 4,560	$ 3,026

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net income	$ 3,873	$ 3,325
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized gains on financial instruments	(90)	(5)
Other-than-temporary impairment losses recognized in income	30	18
(Gain) Loss on extinguishment of debt	(1)	17
Loss on disposal of assets	1	2
Deferred income taxes	(29)	141
Amortization, net of accretion	778	752
Depreciation expense	109	92
Share-based compensation	226	135
Changes in operating assets and liabilities:
Receivables, net	(880)	(823)
Other invested assets	(30)	(17)
Other assets	(280)	(734)
Policy liabilities	1,394	(556)
Unearned income	46	(42)
Accounts payable and accrued expenses	(931)	756
Other liabilities	675	190
Income taxes	(81)	273
Other, net	(76)	(160)
Net cash provided by operating activities	4,734	3,364
Investing activities
Purchases of fixed maturity securities	(7,616)	(6,790)
Proceeds from fixed maturity securities:
Sales	3,919	4,971
Maturities, calls and redemptions	1,583	1,442
Purchases of equity securities	(9,408)	(812)
Proceeds from sales of equity securities	8,671	2,119
Purchases of other invested assets	(286)	(324)
Proceeds from sales of other invested assets	242	251
Changes in securities lending collateral	139	(286)
Purchases of subsidiaries, net of cash acquired	0	(1,732)
Purchases of property and equipment	(726)	(888)
Other, net	(33)	17
Net cash used in investing activities	(3,515)	(2,032)
Financing activities
Net repayments of commercial paper borrowings	(197)	(54)
Proceeds from long-term borrowings	2,473	835
Repayments of long-term borrowings	(923)	(1,393)
Proceeds from short-term borrowings	6,480	5,300
Repayments of short-term borrowings	(6,915)	(5,305)
Changes in securities lending payable	(139)	287
Changes in bank overdrafts	250	97
Proceeds from issuance of common stock under Equity Units stock purchase contracts	0	1,250
Repurchase and retirement of common stock	(1,396)	(1,192)
Change in collateral and settlements of debt-related derivatives	(34)	22
Cash dividends	(616)	(583)
Proceeds from issuance of common stock under employee stock plans	137	133
Taxes paid through withholding of common stock under employee stock plans	(82)	(77)
Net cash used in financing activities	(962)	(680)
Effect of foreign exchange rates on cash and cash equivalents	(1)	(1)
Change in cash and cash equivalents	256	651
Cash and cash equivalents at beginning of period	3,934	3,609
Cash and cash equivalents at end of period	$ 4,190	$ 4,260

Consolidated Statements Of Shar

Consolidated Statements Of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]
Cumulative effect of new accounting principle in period of adoption				$ 320	$ (320)
Adjusted beginning balance	$ 26,503		$ 8,547	18,374	(421)
Balance at Dec. 31, 2017	26,503	$ 3	8,547	18,054	(101)
Balance (in shares) at Dec. 31, 2017		256.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,312			1,312
Other comprehensive income (loss)	(209)				(209)
Repurchase and retirement of common stock, value	(394)	$ 0	(56)	(338)
Repurchase and retirement of common stock, shares		(1.7)
Dividends and dividend equivalents	(198)			(198)
Issuance of common stock under employee stock plans, net of related tax benefits, Shares		1.1
Issuance of common stock under employee stock plans, net of related tax benefits	28		28
Convertible debenture repurchases and conversions	(30)		(30)
Adoption of ASU 2018-02 (Note 2)				91	(91)
Balance at Mar. 31, 2018	27,012	$ 3	8,489	19,241	(721)
Balance (in shares) at Mar. 31, 2018		255.5
Balance at Dec. 31, 2017	26,503	$ 3	8,547	18,054	(101)
Balance (in shares) at Dec. 31, 2017		256.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,325
Other comprehensive income (loss)	(299)
Repurchase and retirement of common stock, value	$ (1,192)
Repurchase and retirement of common stock, shares	(5)
Balance at Sep. 30, 2018	$ 29,094	$ 3	9,720	20,182	(811)
Balance (in shares) at Sep. 30, 2018		258.9
Balance at Mar. 31, 2018	27,012	$ 3	8,489	19,241	(721)
Balance (in shares) at Mar. 31, 2018		255.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,053			1,053
Other comprehensive income (loss)	(61)				(61)
Issuance of common stock under Equity Units stock purchase contracts, shares		6
Issuance of common stock under Equity Units stock purchase contracts	1,250		1,250
Repurchase and retirement of common stock, value	(401)	$ 0	(60)	(341)
Repurchase and retirement of common stock, shares		(1.7)
Dividends and dividend equivalents	(197)			(197)
Issuance of common stock under employee stock plans, net of related tax benefits, Shares		0.3
Issuance of common stock under employee stock plans, net of related tax benefits	69		69
Balance at Jun. 30, 2018	28,725	$ 3	9,748	19,756	(782)
Balance (in shares) at Jun. 30, 2018		260.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	960			960
Other comprehensive income (loss)	(29)				(29)
Repurchase and retirement of common stock, value	(397)	$ 0	(58)	(339)
Repurchase and retirement of common stock, shares		(1.6)
Dividends and dividend equivalents	(195)			(195)
Issuance of common stock under employee stock plans, net of related tax benefits, Shares		0.4
Issuance of common stock under employee stock plans, net of related tax benefits	95		95
Convertible debenture repurchases and conversions	(65)		(65)
Balance at Sep. 30, 2018	29,094	$ 3	9,720	20,182	(811)
Balance (in shares) at Sep. 30, 2018		258.9
Cumulative effect of new accounting principle in period of adoption	26			26
Adjusted beginning balance	28,567		9,536	20,014	(986)
Balance at Dec. 31, 2018	28,541	$ 3	9,536	19,988	(986)
Balance (in shares) at Dec. 31, 2018		257.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,551			1,551
Other comprehensive income (loss)	363				363
Repurchase and retirement of common stock, value	(294)	$ 0	(71)	(223)
Repurchase and retirement of common stock, shares		(1.1)
Dividends and dividend equivalents	(206)			(206)
Issuance of common stock under employee stock plans, net of related tax benefits, Shares		1.1
Issuance of common stock under employee stock plans, net of related tax benefits	69		69
Convertible debenture repurchases and conversions	(52)		(52)
Balance at Mar. 31, 2019	29,998	$ 3	9,482	21,136	(623)
Balance (in shares) at Mar. 31, 2019		257.4
Balance at Dec. 31, 2018	28,541	$ 3	9,536	19,988	(986)
Balance (in shares) at Dec. 31, 2018		257.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,873
Other comprehensive income (loss)	687
Repurchase and retirement of common stock, value	$ (1,396)
Repurchase and retirement of common stock, shares	(5.2)
Balance at Sep. 30, 2019	$ 31,332	$ 3	9,524	22,104	(299)
Balance (in shares) at Sep. 30, 2019		253.8
Balance at Mar. 31, 2019	29,998	$ 3	9,482	21,136	(623)
Balance (in shares) at Mar. 31, 2019		257.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,139			1,139
Other comprehensive income (loss)	240				240
Repurchase and retirement of common stock, value	(458)	$ 0	(70)	(388)
Repurchase and retirement of common stock, shares		(1.7)
Dividends and dividend equivalents	(208)			(208)
Issuance of common stock under employee stock plans, net of related tax benefits, Shares		0.2
Issuance of common stock under employee stock plans, net of related tax benefits	91		91
Convertible debenture repurchases and conversions	(9)		(9)
Balance at Jun. 30, 2019	30,793	$ 3	9,494	21,679	(383)
Balance (in shares) at Jun. 30, 2019		255.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,183			1,183
Other comprehensive income (loss)	84				84
Repurchase and retirement of common stock, value	(644)	$ 0	(90)	(554)
Repurchase and retirement of common stock, shares		(2.4)
Dividends and dividend equivalents	(204)			(204)
Issuance of common stock under employee stock plans, net of related tax benefits, Shares		0.3
Issuance of common stock under employee stock plans, net of related tax benefits	120		120
Balance at Sep. 30, 2019	$ 31,332	$ 3	$ 9,524	$ 22,104	$ (299)
Balance (in shares) at Sep. 30, 2019		253.8

Organization

Organization	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization References to the terms “we,” “our,” “us” or “Anthem” used throughout these Notes to Consolidated Financial Statements refer to Anthem, Inc., an Indiana corporation, and unless the context otherwise requires, its direct and indirect subsidiaries. References to the “states” include the District of Columbia, unless the context otherwise requires. We are one of the largest health benefits companies in the United States in terms of medical membership, serving approximately 41 medical members through our affiliated health plans as of September 30, 2019 . We offer a broad spectrum of network-based managed care plans to Large Group, Small Group, Individual, Medicaid and Medicare markets. Our managed care plans include: Preferred Provider Organizations, or PPOs; Health Maintenance Organizations, or HMOs; Point-of-Service plans; traditional indemnity plans and other hybrid plans, including Consumer-Driven Health Plans, and hospital only and limited benefit products. In addition, we provide a broad array of managed care services to self-funded customers, including claims processing, stop loss insurance, actuarial services, provider network access, medical cost management, disease management, wellness programs and other administrative services. We provide an array of specialty and other insurance products and services such as dental, vision, life and disability insurance benefits, radiology benefit management and analytics-driven personal health care. We also provide services to the federal government in connection with our Federal Health Products & Services business. We are an independent licensee of the Blue Cross and Blue Shield Association, or BCBSA, an association of independent health benefit plans. We serve our members as the Blue Cross licensee for California and as the Blue Cross and Blue Shield, or BCBS, licensee for Colorado, Connecticut, Georgia, Indiana, Kentucky, Maine, Missouri (excluding 30 counties in the Kansas City area), Nevada, New Hampshire, New York (in the New York City metropolitan area and upstate New York), Ohio, Virginia (excluding the Northern Virginia suburbs of Washington, D.C.) and Wisconsin. In a majority of these service areas, we do business as Anthem Blue Cross, Anthem Blue Cross and Blue Shield, and Empire Blue Cross Blue Shield or Empire Blue Cross. We also conduct business through arrangements with other BCBS licensees. Through our subsidiaries, we serve customers in numerous states across the country as America’s 1st Choice, Amerigroup, Aspire Health, CareMore, Freedom Health, HealthLink, HealthSun, Optimum HealthCare, Simply Healthcare, and/or Unicare. Also, beginning in the second quarter of 2019, we provide pharmacy benefits management services through our IngenioRx subsidiary. We are licensed to conduct insurance operations in all 50

Basis Of Presentation and Signi

Basis Of Presentation and Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	Basis of Presentation and Significant Accounting Policies Basis of Presentation: The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP, for interim financial reporting. Accordingly, they do not include all of the information and footnotes required by GAAP for annual financial statements. We have omitted certain footnote disclosures that would substantially duplicate the disclosures in our 2018 Annual Report on Form 10-K, unless the information contained in those disclosures materially changed or is required by GAAP. Certain prior year amounts have been reclassified to conform to the current year presentation or adjusted to conform to the current year rounding convention of reporting financial data in whole millions of dollars, except as otherwise noted. For additional information on prior year reclassifications, see Note 15, “Segment Information.” In the opinion of management, all adjustments, including normal recurring adjustments, necessary for a fair statement of the consolidated financial statements as of and for the three and nine months ended September 30, 2019 and 2018 have been recorded. The results of operations for the three and nine months ended September 30, 2019 are not necessarily indicative of the results that may be expected for the full year ending December 31, 2019 , or any other period. These unaudited consolidated financial statements should be read in conjunction with our audited consolidated financial statements as of and for the year ended December 31, 2018 included in our 2018 Annual Report on Form 10-K. Certain of our subsidiaries operate outside of the United States and have functional currencies other than the U.S. dollar, or USD. We translate the assets and liabilities of those subsidiaries to USD using the exchange rate in effect at the end of the period. We translate the revenues and expenses of those subsidiaries to USD using the average exchange rates in effect during the period. The net effect of these translation adjustments is included in “Foreign currency translation adjustments” in our consolidated statements of comprehensive income. Cash and Cash Equivalents: We control a number of bank accounts that are used exclusively to hold customer funds for the administration of customer benefits and have cash and cash equivalents on deposit to meet certain regulatory requirements. These amounts totaled $242 and $222 at September 30, 2019 and December 31, 2018 , respectively, and are included in the cash and cash equivalents line on our consolidated balance sheets. Leases: We lease office space and certain computer and related equipment under noncancelable operating leases. We determine whether an arrangement is or contains a lease at its inception. We recognize lease liabilities based on the present value of the minimum lease payments not yet paid by using the lease term, any amounts probable of being owed under any residual value guarantees and discount rate determined at lease commencement. As our leases do not generally provide an implicit rate, we use our incremental secured borrowing rate commensurate with the underlying lease terms to determine the present value of our lease payments. Our leases may include options to extend or terminate a lease when it is reasonably certain that we will exercise that option. We recognize the operating right-of-use, or ROU, assets at an amount equal to the lease liability adjusted for prepaid or accrued rent, the remaining balance of any lease incentives and unamortized initial direct costs. The operating lease liabilities are reported in other current liabilities and other noncurrent liabilities and the related ROU assets are reported in other noncurrent assets on our consolidated balance sheet as of September 30, 2019 . Lease expense for our operating leases is calculated on a straight-line basis over the lease term and is reported in selling, general and administrative expense on our consolidated statements of income. For our office space leases, we account for the lease and non-lease components (such as common area maintenance) as a single lease component. We also do not recognize a lease liability or ROU asset for our office space leases whose lease terms, at commencement, are twelve months or less and that do not include a purchase option or option to extend that we are reasonably certain to exercise. Revenue Recognition: Premiums for fully-insured contracts are recognized as revenue over the period insurance coverage is provided, and, if applicable, net of amounts recognized for the minimum medical loss ratio rebates or contractual or government-mandated premium stabilization programs. Administrative fees and other revenues include revenue from certain group contracts that provide for the group to be at risk for all, or with supplemental insurance arrangements, a portion of their claims experience. We charge these self-funded groups an administrative fee, which is based on the number of members in a group or the group’s claim experience. Under our self-funded arrangements, revenue is recognized as administrative services are performed, and benefit payments under these programs are excluded from benefit expense. Beginning in the second quarter of 2019, administrative fees and other revenues also include unaffiliated revenue from services performed by IngenioRx. For additional information about our revenues, see Note 2, “Basis of Presentation and Significant Accounting Policies” and Note 19, “Segment Information,” to our audited consolidated financial statements as of and for the year ended December 31, 2018 included in our 2018 Annual Report on Form 10-K. In addition, see Note 15, “Segment Information,” herein for the disaggregation of revenues by segments and products. For our non-fully-insured contracts, we had no material contract assets, contract liabilities or deferred contract costs recorded on our consolidated balance sheet at September 30, 2019 . For the three and nine months ended September 30, 2019 , revenue recognized from performance obligations related to prior periods, such as due to changes in transaction price, was not material. For contracts that have an original expected duration of greater than one year, revenue expected to be recognized in future periods related to unfulfilled contractual performance obligations and contracts with variable consideration related to undelivered performance obligations is not material. Recently Adopted Accounting Guidance: In March 2019, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update No. 2019-01, Leases (Topic 842): Codification Improvements . In July 2018, the FASB issued Accounting Standards Update No. 2018-11, Leases (Topic 842): Targeted Improvements and Accounting Standards Update No. 2018-10, Codification Improvements to Topic 842, Leases . These updates provide additional clarification, an optional transition method, a practical expedient and implementation guidance on the previously issued Accounting Standards Update No. 2016-02, Leases (Topic 842) . Collectively, these updates supersede the lease guidance in Accounting Standards Codification, or ASC, Topic 840 and require lessees to recognize for all leases, with the exception of short-term leases, a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis. Concurrently, lessees are required to recognize an ROU asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. We adopted this standard on January 1, 2019 by applying the optional transition method on the adoption date and did not adjust comparative periods. We also elected the package of practical expedients permitted, which, among other things, allowed us to carry forward the lease classification for our existing leases. In preparation for the adoption of this standard and to enable preparation of the required financial information, we implemented a new lease accounting software solution as well as new internal controls. The adoption of this standard impacted our 2019 opening consolidated balance sheet, as we recorded operating lease liabilities of $728 and ROU assets of $637 , which equals the lease liabilities net of accrued rent, lease incentives and the carrying amount of ceased-use liabilities previously recorded on our consolidated balance sheet under the old guidance. We also recognized a cumulative-effect adjustment of $26 to our opening retained earnings for deferred gains on our previous sale-leaseback transactions. The adoption of this standard did not have an impact on our consolidated statements of income or cash flows. In August 2018, the FASB issued Accounting Standards Update No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, or ASU 2018-13. The amendments in ASU 2018-13 eliminate, add, and modify certain disclosure requirements for fair value measurements. The amendments are effective for interim and annual periods beginning after December 15, 2019, with early adoption permitted for either the entirety of ASU 2018-13 or only the provisions that eliminate or modify disclosure requirements. We early adopted the provisions that eliminate and modify disclosure requirements, on a retrospective basis, effective in our 2018 Annual Report on Form 10-K. We will adopt the new disclosure requirements, on a prospective basis, effective for our interim and annual reporting periods beginning after December 15, 2019. In February 2018, the FASB issued Accounting Standards Update No. 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , or ASU 2018-02. On December 22, 2017, the federal government enacted a tax bill, H.R.1, An act to provide for reconciliation pursuant to titles II and V of the concurrent resolution on the budget for fiscal year 2018 , or the Tax Cuts and Jobs Act. The Tax Cuts and Jobs Act contains significant changes to corporate taxation, including, but not limited to, reducing the U.S. federal corporate income tax rate from 35% to 21% and modifying or limiting many business deductions. Current FASB guidance requires adjustments of deferred taxes due to a change in the federal corporate income tax rate to be included in income from operations. As a result, the tax effects of items within accumulated other comprehensive loss did not reflect the appropriate tax rate. The amendments in ASU 2018-02 allowed a reclassification from accumulated other comprehensive loss to retained earnings for stranded tax effects resulting from the change in the federal corporate income tax rate. We adopted the amendments in ASU 2018-02 for our interim and annual reporting periods beginning on January 1, 2018 and reclassified $91 of stranded tax effects from accumulated other comprehensive loss to retained earnings on our consolidated balance sheets. The adoption of ASU 2018-02 did not have any impact on our consolidated results of operations or cash flows. In May 2017, the FASB issued Accounting Standards Update No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting , or ASU 2017-09. This update provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in ASC Topic 718. We adopted ASU 2017-09 on January 1, 2018. The guidance has been and will be applied prospectively to awards modified on or after the adoption date. The adoption of ASU 2017-09 did not have any impact on our consolidated financial position, results of operations or cash flows. In March 2017, the FASB issued Accounting Standards Update No. 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities , or ASU 2017-08. This update changes the amortization period for certain purchased callable debt securities held at a premium by shortening the amortization period for the premium to the earliest call date. Under the old guidance, the premium was generally amortized over the contractual life of the instrument. The amendments are to be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. We adopted ASU 2017-08 on January 1, 2019, and the adoption of this standard did not have a material impact on our beginning retained earnings or on our consolidated financial position, results of operations or cash flows. In March 2017, the FASB issued Accounting Standards Update No. 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost , or ASU 2017-07. This amendment requires entities to disaggregate the service cost component from the other components of the benefit cost and present the service cost component in the same income statement line item as other employee compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. Certain of our defined benefit plans have previously been frozen, resulting in no annual service costs, and the remaining service costs for our non-frozen plan are not material. We adopted ASU 2017-07 on January 1, 2018, and it did not have a material impact on our consolidated results of operations, cash flows or financial position. In December 2016, the FASB issued Accounting Standards Update No. 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers. In May 2016, the FASB issued Accounting Standards Update No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients . In April 2016, the FASB issued Accounting Standards Update No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing . In March 2016, the FASB issued Accounting Standards Update No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net) . These updates provide additional clarification and implementation guidance on the previously issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) . Collectively, these updates require a company to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. These updates supersede almost all existing revenue recognition guidance under GAAP, with certain exceptions, including an exception for our premium revenues, which are recorded on the Premiums line item on our consolidated statements of income and will continue to be accounted for in accordance with the provisions of ASC Topic 944, Financial Services - Insurance . Our administrative service and other contracts that are subject to these Accounting Standards Updates are recorded in the Administrative fees and other revenue line item on our consolidated statements of income and represent approximately 6% of our consolidated total operating revenue. We adopted these standards on January 1, 2018 using the modified retrospective approach. The adoption of these standards did not have a material impact on our beginning retained earnings, or on our consolidated results of operations, cash flows or financial position. In November 2016, the FASB issued Accounting Standards Update No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash, or ASU 2016-18. This update amends ASC Topic 230, Statement of Cash Flows , to add and clarify guidance on the classification and presentation of restricted cash in the statement of cash flows. The guidance requires entities to show the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. We adopted ASU 2016-18 on January 1, 2018 using a retrospective approach. The adoption of ASU 2016-18 did not have a material impact on our consolidated statements of cash flows and did not impact our consolidated results of operations or financial position. In August 2016, the FASB issued Accounting Standards Update No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments, or ASU 2016-15. This update addresses the presentation and classification on the statement of cash flows for eight specific items, with the objective of reducing existing diversity in practice in how certain cash receipts and cash payments are presented and classified. We adopted ASU 2016-15 on January 1, 2018. The adoption of ASU 2016-15 did not have a material impact on our consolidated statements of cash flows, results of operations or financial position. In January 2016, the FASB issued Accounting Standards Update No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities , or ASU 2016-01. The amendments in ASU 2016-01 change the accounting for non-consolidated equity investments that are not accounted for under the equity method of accounting by requiring changes in fair value to be recognized in income. Additionally, ASU 2016-01 simplifies the impairment assessment of equity investments without readily determinable fair values; requires entities to use the exit price when estimating the fair value of financial instruments; and modifies various presentation disclosure requirements for financial instruments. We adopted ASU 2016-01 on January 1, 2018 as a cumulative-effect adjustment and reclassified $320 of unrealized gains on equity investments, net of tax, from accumulated other comprehensive loss to retained earnings on our consolidated balance sheets. Effective January 1, 2018, our results of operations include the changes in fair value of these financial instruments. Recent Accounting Guidance Not Yet Adopted: In May 2019, the FASB issued Accounting Standards Update No. 2019-05, Financial Instruments - Credit Losses (Topic 326): Targeted Transition Relief, or ASU 2019-05. In April 2019, the FASB issued Accounting Standards Update No. 2019-04, Codification Improvements to Topic 326, Financial Instruments - Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments . In November 2018, the FASB issued Accounting Standards Update No. 2018-19, Codification Improvements to Topic 326, Financial Instruments - Credit Losses . These updates provide an option to irrevocably elect to measure certain individual financial assets at fair value instead of amortized cost and provide additional clarification and implementation guidance on certain aspects of the previously issued Accounting Standards Update No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, or ASU 2016-13, and have the same effective date and transition requirements as ASU 2016-13. ASU 2016-13 introduces a current expected credit loss model for measuring expected credit losses for certain types of financial instruments held at the reporting date based on historical experience, current conditions and reasonable supportable forecasts. ASU 2016-13 replaces the current incurred loss model for measuring expected credit losses, requires expected losses on available-for-sale debt securities to be recognized through an allowance for credit losses rather than as reductions in the amortized cost of the securities and provides for additional disclosure requirements. ASU 2016-13 requires a cumulative-effect adjustment to the statement of financial position to the opening balance of retained earnings at the date of adoption and a prospective transition approach for debt securities for which an other-than-temporary impairment had been recognized before the adoption date. The effect of a prospective transition approach is to maintain the same amortized cost basis before and after the date of adoption. ASU 2016-13 is effective for us on January 1, 2020, with early adoption permitted. We are currently gathering data and evaluating the effects the adoption of ASU 2016-13 will have on our consolidated financial statements. In August 2018, the FASB issued Accounting Standards Update No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract , or ASU 2018-15. The amendments in ASU 2018-15 require implementation costs incurred by customers in cloud computing arrangements to be deferred and recognized over the term of the arrangement, if those costs would be capitalized by the customer in a software licensing arrangement under the internal-use software guidance. The amendments also require an entity to disclose the nature of its hosting arrangements and adhere to certain presentation requirements in its balance sheet, income statement and statement of cash flows. ASU 2018-15 is effective for us on January 1, 2020, with early adoption permitted. The guidance can be applied either prospectively to all implementation costs incurred after the date of adoption or retrospectively. While we are continuing to evaluate the effects the adoption of ASU 2018-15 will have on our consolidated financial position, results of operations and cash flows; we intend to apply the prospective method of adoption. In August 2018, the FASB issued Accounting Standards Update No. 2018-14, Compensation—Retirement Benefits - Defined Benefit Plans—General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans , or ASU 2018-14. The amendments in ASU 2018-14 eliminate, add, and modify certain disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The amendments are effective for our annual reporting periods beginning after December 15, 2020, with early adoption permitted. The guidance is to be applied on a retrospective basis to all periods presented. We are currently evaluating the effects the adoption of ASU 2018-14 will have on our disclosures. In August 2018, the FASB issued Accounting Standards Update No. 2018-12, Financial Services—Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts, or ASU 2018-12. The amendments in ASU 2018-12 make changes to a variety of areas to simplify or improve the existing recognition, measurement, presentation and disclosure requirements for long-duration contracts issued by an insurance entity. The amendments require insurers to annually review the assumptions they make about their policyholders and update the liabilities for future policy benefits if the assumptions change. The amendments also simplify the amortization of deferred contract acquisition costs and add new disclosure requirements about the assumptions insurers use to measure their liabilities and how they may affect future cash flows. The amendments in ASU 2018-12 will be effective for our interim and annual reporting periods beginning after December 15, 2020. The amendments related to the liability for future policy benefits for traditional and limited-payment contracts and deferred acquisition costs are to be applied to contracts in force as of the beginning of the earliest period presented, with an option to apply such amendments retrospectively with a cumulative-effect adjustment to the opening balance of retained earnings as of the earliest period presented. The amendments for market risk benefits are to be applied retrospectively. We are currently evaluating the effects the adoption of ASU 2018-12 will have on our consolidated financial position, results of operations, cash flows, and related disclosures. In January 2017, the FASB issued Accounting Standards Update No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment , or ASU 2017-04. This update removes Step 2 of the goodwill impairment test under current guidance, which requires a hypothetical purchase price allocation. The new guidance requires an impairment charge to be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value. Upon adoption, the guidance is to be applied prospectively. ASU 2017-04 is effective for us on January 1, 2020, with early adoption permitted. The adoption of ASU 2017-04 is not expected to have a material impact on our consolidated financial position, results of operations or cash flows. There were no other new accounting pronouncements that were issued or became effective since the issuance of our 2018 Annual Report on Form 10-K that had, or are expected to have, a material impact on our consolidated financial position, results of operations or cash flows.

Business Acquisitions

Business Acquisitions	9 Months Ended
	Sep. 30, 2019
Business Combinations [Abstract]
Business Acquisitions	Business Acquisitions Pending Acquisition of Beacon On June 6, 2019, we announced our entrance into an agreement to acquire Beacon Health Options, Inc., or Beacon, the largest independently held behavioral health organization in the country. Beacon serves approximately forty million individuals across all fifty states. This acquisition aligns with our strategy to diversify into health services and deliver both integrated solutions and care delivery models that personalize care for people with complex and chronic conditions. The acquisition is expected to close late in the fourth quarter of 2019 and is subject to standard closing conditions and customary approvals. Acquisition of America’s 1st Choice On February 15, 2018, we completed our acquisition of Freedom Health, Inc., Optimum HealthCare, Inc., America’s 1st Choice of South Carolina, Inc. and related entities, or collectively, America’s 1st Choice, a Medicare Advantage organization that offers HMO products, including Chronic Special Needs Plans and Dual-Eligible Special Needs Plans under its Freedom Health and Optimum HealthCare brands in Florida and its America’s 1st Choice of South Carolina brand in South Carolina. Upon the conclusion of our one-year measurement period, the excess of the consideration transferred over the fair value of the net assets acquired resulted in goodwill of $1,029 , of which $333

Investments

Investments	9 Months Ended
	Sep. 30, 2019
Investments [Abstract]
Investments	Investments Fixed Maturity Securities We evaluate our available-for-sale fixed maturity securities for other-than-temporary declines based on qualitative and quantitative factors. There were no individually significant other-than-temporary impairment losses on investments during the three and nine months ended September 30, 2019 and 2018 . We continue to review our investment portfolios under our impairment review policy. Given the inherent uncertainty of changes in market conditions and the significant judgments involved, there is a continuing risk that declines in fair value may occur and additional material other-than-temporary impairment, or OTTI, losses on investments may be recorded in future periods. A summary of current and long-term fixed maturity securities, available-for-sale, at September 30, 2019 and December 31, 2018 is as follows: Non-Credit Component of OTTIs Other Comprehensive Loss Cost or Gross Gross Unrealized Losses Estimated Less than 12 Months 12 Months or Greater September 30, 2019 Fixed maturity securities: United States Government securities $ 487 $ 10 $ — $ — $ 497 $ — Government sponsored securities 125 6 — — 131 — States, municipalities and political subdivisions 4,469 275 (1 ) (1 ) 4,742 — Corporate securities 9,040 341 (17 ) (25 ) 9,339 (5 ) Residential mortgage-backed securities 3,914 111 (4 ) (4 ) 4,017 — Commercial mortgage-backed securities 87 3 — — 90 — Other securities 1,645 24 (2 ) (5 ) 1,662 — Total fixed maturity securities $ 19,767 $ 770 $ (24 ) $ (35 ) $ 20,478 $ (5 ) December 31, 2018 Fixed maturity securities: United States Government securities $ 414 $ 3 $ — $ (1 ) $ 416 $ — Government sponsored securities 108 1 — (1 ) 108 — States, municipalities and political subdivisions 4,716 91 (3 ) (19 ) 4,785 — Corporate securities 8,189 33 (170 ) (115 ) 7,937 (3 ) Residential mortgage-backed securities 2,769 31 (3 ) (47 ) 2,750 — Commercial mortgage-backed securities 69 — — (2 ) 67 — Other securities 1,115 14 (8 ) (5 ) 1,116 — Total fixed maturity securities $ 17,380 $ 173 $ (184 ) $ (190 ) $ 17,179 $ (3 ) For fixed maturity securities in an unrealized loss position at September 30, 2019 and December 31, 2018 , the following table summarizes the aggregate fair values and gross unrealized losses by length of time those securities have continuously been in an unrealized loss position: Less than 12 Months 12 Months or Greater (Securities are whole amounts) Number of Securities Estimated Fair Value Gross Unrealized Loss Number of Securities Estimated Fair Value Gross Unrealized Loss September 30, 2019 Fixed maturity securities: United States Government securities 8 $ 49 $ — 5 $ 14 $ — Government sponsored securities 6 5 — 3 1 — States, municipalities and political subdivisions 66 108 (1 ) 16 13 (1 ) Corporate securities 455 711 (17 ) 338 509 (25 ) Residential mortgage-backed securities 228 422 (4 ) 215 323 (4 ) Commercial mortgage-backed securities 1 3 — 4 8 — Other securities 190 483 (2 ) 107 332 (5 ) Total fixed maturity securities 954 $ 1,781 $ (24 ) 688 $ 1,200 $ (35 ) December 31, 2018 Fixed maturity securities: United States Government securities 5 $ 47 $ — 25 $ 79 $ (1 ) Government sponsored securities 8 11 — 24 31 (1 ) States, municipalities and political subdivisions 177 295 (3 ) 604 1,032 (19 ) Corporate securities 2,185 4,503 (170 ) 1,220 2,072 (115 ) Residential mortgage-backed securities 259 383 (3 ) 816 1,458 (47 ) Commercial mortgage-backed securities 6 11 — 19 37 (2 ) Other securities 193 599 (8 ) 93 237 (5 ) Total fixed maturity securities 2,833 $ 5,849 $ (184 ) 2,801 $ 4,946 $ (190 ) The amortized cost and fair value of fixed maturity securities at September 30, 2019 , by contractual maturity, are shown below. Expected maturities may differ from contractual maturities because the issuers of the securities may have the right to prepay obligations. Amortized Cost Estimated Fair Value Due in one year or less $ 628 $ 628 Due after one year through five years 5,569 5,701 Due after five years through ten years 5,504 5,731 Due after ten years 4,065 4,311 Mortgage-backed securities 4,001 4,107 Total fixed maturity securities $ 19,767 $ 20,478 Proceeds from sales, maturities, calls or redemptions of fixed maturity securities and the related gross realized gains and gross realized losses for the three and nine months ended September 30, 2019 and 2018 are as follows: Three Months Ended Nine Months Ended 2019 2018 2019 2018 Proceeds $ 2,048 $ 1,532 $ 5,502 $ 6,413 Gross realized gains 26 12 66 73 Gross realized losses (9 ) (16 ) (43 ) (85 ) In the ordinary course of business, we may sell securities at a loss for a number of reasons, including, but not limited to: (i) changes in the investment environment; (ii) expectation that the fair value could deteriorate further; (iii) desire to reduce exposure to an issuer or an industry; (iv) changes in credit quality; or (v) changes in expected cash flow. All securities sold resulting in investment gains and losses are recorded on the trade date. Realized gains and losses are determined on the basis of the cost or amortized cost of the specific securities sold. Equity Securities A summary of current and long-term marketable equity securities at September 30, 2019 and December 31, 2018 is as follows: September 30, 2019 December 31, 2018 Equity securities: Exchange traded funds $ 563 $ 2 Fixed maturity mutual funds 631 557 Common equity securities 829 654 Private equity securities 306 313 Total $ 2,329 $ 1,526 The gains and losses related to equity securities for the three and nine months ended September 30, 2019 and 2018 are as follows: Three Months Ended September 30 Nine Months Ended September 30 2019 2018 2019 2018 Net realized (losses) gains recognized on equity securities $ (16 ) $ 27 $ 75 $ (33 ) Less: Net realized gains recognized on equity securities sold during the period (6 ) (11 ) (55 ) (208 ) Unrealized (losses) gains recognized on equity securities still held at September 30 $ (22 ) $ 16 $ 20 $ (241 ) Securities Lending Programs We participate in securities lending programs whereby marketable securities in our investment portfolio are transferred to independent brokers or dealers in exchange for cash and securities collateral. The fair value of the collateral received at the time of the transactions amounted to $465 and $604 at September 30, 2019 and December 31, 2018 , respectively. The value of the collateral represented 103% and 102% of the market value of the securities on loan at September 30, 2019 and December 31, 2018 , respectively. We recognize the collateral as an asset under the caption “Securities lending collateral” on our consolidated balance sheets, and we recognize a corresponding liability for the obligation to return the collateral to the borrower under the caption “Securities lending payable.” The securities on loan are reported in the applicable investment category on our consolidated balance sheets. The remaining contractual maturity of our securities lending agreements at September 30, 2019 is as follows: Overnight and Continuous Securities lending transactions United States Government securities $ 132 Corporate securities 324 Equity securities 9 Total $ 465 The market value of loaned securities and that of the collateral pledged can fluctuate in non-synchronized fashions. To the extent the loaned securities’ value appreciates faster or depreciates slower than the value of the collateral pledged, we are exposed to the risk of the shortfall. As a primary mitigating mechanism, the loaned securities and collateral pledged are marked to market on a daily basis and the shortfall, if any, is collected accordingly. Secondarily, the minimum collateral level is set at 102%

Derivative Financial Instrument

Derivative Financial Instruments Derivative Financial Instruments	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments We primarily invest in the following types of derivative financial instruments: interest rate swaps, futures, forward contracts, put and call options, swaptions, embedded derivatives and warrants. We also enter into master netting agreements, which reduce credit risk by permitting net settlement of transactions. We have entered into various interest rate swap contracts to convert a portion of our interest rate exposure on our long-term debt from fixed rates to floating rates. The floating rates payable on all of our fair value hedges are benchmarked to the London Interbank Offered Rate. Prior to 2019, we entered into a series of forward starting pay fixed interest rate swaps with the objective of reducing the variability of cash flows in the interest payments on anticipated future financings. The unrecognized loss for all expired and terminated cash flow hedges included in accumulated other comprehensive loss, net of tax, was $277 and $ 246 at September 30, 2019 and December 31, 2018 , respectively. For additional information relating to the fair value of our derivative assets and liabilities, see Note 6, “Fair Value,” of this Form 10-Q.

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value	Fair Value Assets and liabilities recorded at fair value in our consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair value. Level inputs, as defined by FASB guidance for fair value measurements and disclosures, are as follows: Level Input Input Definition Level I Inputs are unadjusted, quoted prices for identical assets or liabilities in active markets at the measurement date. Level II Inputs other than quoted prices included in Level I that are observable for the asset or liability through corroboration with market data at the measurement date. Level III Unobservable inputs that reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. The following methods, assumptions and inputs were used to determine the fair value of each class of the following assets and liabilities recorded at fair value in our consolidated balance sheets: Cash equivalents: Cash equivalents primarily consist of highly rated money market funds with maturities of three months or less and are purchased daily at par value with specified yield rates. Due to the high ratings and short-term nature of the funds, we designate all cash equivalents as Level I. Fixed maturity securities, available-for-sale: Fair values of available-for-sale fixed maturity securities are based on quoted market prices, where available. These fair values are obtained primarily from third party pricing services, which generally use Level I or Level II inputs for the determination of fair value to facilitate fair value measurements and disclosures. Level II securities primarily include United States Government securities, corporate securities, securities from states, municipalities and political subdivisions, mortgage-backed securities and certain other asset-backed securities. For securities not actively traded, the pricing services may use quoted market prices of comparable instruments or discounted cash flow analyses, incorporating inputs that are currently observable in the markets for similar securities. We have controls in place to review the pricing services’ qualifications and procedures used to determine fair values. In addition, we periodically review the pricing services’ pricing methodologies, data sources and pricing inputs to ensure the fair values obtained are reasonable. Inputs that are often used in the valuation methodologies include, but are not limited to, broker quotes, benchmark yields, credit spreads, default rates and prepayment speeds. We also have certain fixed maturity securities, primarily corporate debt securities, which are designated Level III securities. For these securities, the valuation methodologies may incorporate broker quotes or discounted cash flow analyses using assumptions for inputs such as expected cash flows, benchmark yields, credit spreads, default rates and prepayment speeds that are not observable in the markets. Equity securities: Fair values of equity securities with quoted market prices are designated as Level I. For certain equity securities, quoted market prices for the identical security are not always available and the fair value is estimated by reference to similar securities for which quoted prices are available. These securities are designated Level II. We also have certain equity securities, including private equity securities, for which the fair value is estimated based on each security’s current condition and future cash flow projections. Such securities are designated Level III. The fair values of these private equity securities are generally based on either broker quotes or discounted cash flow projections using assumptions for inputs such as the weighted-average cost of capital, long-term revenue growth rates and earnings before interest, taxes, depreciation and amortization, and/or revenue multiples that are not observable in the markets. Other invested assets, current: Other invested assets, current include securities held in rabbi trusts that are classified as trading. These securities are designated Level I securities, as fair values are based on quoted market prices. Securities lending collateral: Fair values of securities lending collateral are based on quoted market prices, where available. These fair values are obtained primarily from third party pricing services, which generally use Level I or Level II inputs for the determination of fair value, to facilitate fair value measurements and disclosures. Derivatives: Fair values are based on the quoted market prices by the financial institution that is the counterparty to the derivative transaction. We independently verify prices provided by the counterparties using valuation models that incorporate observable market inputs for similar derivative transactions. Derivatives are designated as Level II securities. Derivatives presented within the fair value hierarchy table below are presented on a gross basis and not on a master netting basis by counterparty. A summary of fair value measurements by level for assets and liabilities measured at fair value on a recurring basis at September 30, 2019 and December 31, 2018 is as follows: Level I Level II Level III Total September 30, 2019 Assets: Cash equivalents $ 1,258 $ — $ — $ 1,258 Fixed maturity securities, available-for-sale: United States Government securities — 497 — 497 Government sponsored securities — 131 — 131 States, municipalities and political subdivisions — 4,742 — 4,742 Corporate securities — 9,028 311 9,339 Residential mortgage-backed securities — 4,014 3 4,017 Commercial mortgage-backed securities — 90 — 90 Other securities — 1,651 11 1,662 Total fixed maturity securities, available-for-sale — 20,153 325 20,478 Equity securities: Exchange traded funds 563 — — 563 Fixed maturity mutual funds — 631 — 631 Common equity securities 796 33 — 829 Private equity securities — — 306 306 Total equity securities 1,359 664 306 2,329 Other invested assets, current 10 — — 10 Securities lending collateral — 465 — 465 Derivatives — 25 — 25 Total assets $ 2,627 $ 21,307 $ 631 $ 24,565 Liabilities: Derivatives $ — $ (1 ) $ — $ (1 ) Total liabilities $ — $ (1 ) $ — $ (1 ) December 31, 2018 Assets: Cash equivalents $ 1,815 $ — $ — $ 1,815 Fixed maturity securities, available-for-sale: United States Government securities — 416 — 416 Government sponsored securities — 108 — 108 States, municipalities and political subdivisions — 4,785 — 4,785 Corporate securities 2 7,648 287 7,937 Residential mortgage-backed securities — 2,744 6 2,750 Commercial mortgage-backed securities — 67 — 67 Other securities — 1,099 17 1,116 Total fixed maturity securities, available-for-sale 2 16,867 310 17,179 Equity securities: Exchange traded funds 2 — — 2 Fixed maturity mutual funds — 557 — 557 Common equity securities 601 53 — 654 Private equity securities — — 313 313 Total equity securities 603 610 313 1,526 Other invested assets, current 21 — — 21 Securities lending collateral 314 290 — 604 Derivatives — 16 — 16 Total assets $ 2,755 $ 17,783 $ 623 $ 21,161 Liabilities: Derivatives $ — $ (17 ) $ — $ (17 ) Total liabilities $ — $ (17 ) $ — $ (17 ) A reconciliation of the beginning and ending balances of assets measured at fair value on a recurring basis using Level III inputs for the three months ended September 30, 2019 and 2018 is as follows: Corporate Securities Residential Mortgage- backed Securities Other Securities Equity Securities Total Three Months Ended September 30, 2019 Beginning balance at July 1, 2019 $ 297 $ 3 $ 11 $ 305 $ 616 Total gains (losses): Recognized in net income (3 ) — — (5 ) (8 ) Recognized in accumulated other comprehensive loss 12 — — — 12 Purchases 28 — — 25 53 Sales (9 ) — — (19 ) (28 ) Settlements (18 ) — — — (18 ) Transfers into Level III 4 — — — 4 Transfers out of Level III — — — — — Ending balance at September 30, 2019 $ 311 $ 3 $ 11 $ 306 $ 631 Change in unrealized losses included in net income related to assets still held at September 30, 2019 $ — $ — $ — $ (4 ) $ (4 ) Three Months Ended September 30, 2018 Beginning balance at July 1, 2018 $ 304 $ 4 $ 26 $ 312 $ 646 Total gains (losses): Recognized in net income — — — 4 4 Recognized in accumulated other comprehensive loss (1 ) — — — (1 ) Purchases 32 — 3 5 40 Sales (2 ) — — (3 ) (5 ) Settlements (30 ) — — — (30 ) Transfers into Level III 6 — 1 — 7 Transfers out of Level III (2 ) — (13 ) — (15 ) Ending balance at September 30, 2018 $ 307 $ 4 $ 17 $ 318 $ 646 Change in unrealized gains included in net income related to assets still held at September 30, 2018 $ — $ — $ — $ 9 $ 9 A reconciliation of the beginning and ending balances of assets measured at fair value on a recurring basis using Level III inputs for the nine months ended September 30, 2019 and 2018 is as follows: Corporate Securities Residential Mortgage- backed Securities Other Securities Equity Securities Total Nine Months Ended September 30, 2019 Beginning balance at January 1, 2019 $ 287 $ 6 $ 17 $ 313 $ 623 Total (losses) gains: Recognized in net income (7 ) — — (5 ) (12 ) Recognized in accumulated other comprehensive loss 14 — — — 14 Purchases 91 — 2 46 139 Sales (11 ) — — (48 ) (59 ) Settlements (58 ) (1 ) (2 ) — (61 ) Transfers into Level III 4 — 3 — 7 Transfers out of Level III (9 ) (2 ) (9 ) — (20 ) Ending balance at September 30, 2019 $ 311 $ 3 $ 11 $ 306 $ 631 Change in unrealized losses included in net income related to assets still held at September 30, 2019 $ — $ — $ — $ (4 ) $ (4 ) Nine Months Ended September 30, 2018 Beginning balance at January 1, 2018 $ 229 $ 5 $ 16 $ 287 $ 537 Total (losses) gains: Recognized in net income 1 — — (228 ) (227 ) Recognized in accumulated other comprehensive loss (3 ) — — — (3 ) Purchases 94 — 12 263 369 Sales (17 ) — — (4 ) (21 ) Settlements (60 ) (1 ) (1 ) — (62 ) Transfers into Level III 65 — 5 — 70 Transfers out of Level III (2 ) — (15 ) — (17 ) Ending balance at September 30, 2018 $ 307 $ 4 $ 17 $ 318 $ 646 Change in unrealized gains included in net income related to assets still held at September 30, 2018 $ — $ — $ — $ 27 $ 27 There were no individually material transfers into or out of Level III during the three and nine months ended September 30, 2019 or 2018 . Certain assets and liabilities are measured at fair value on a nonrecurring basis; that is, the instruments are not measured at fair value on an ongoing basis but are subject to fair value adjustments only in certain circumstances. As disclosed in Note 3, “Business Acquisitions,” we completed our acquisition of America’s 1st Choice on February 15, 2018. The net assets acquired in our acquisition of America’s 1st Choice and resulting goodwill and other intangible assets were recorded at fair value primarily using Level III inputs. The majority of America’s 1st Choice’s assets acquired and liabilities assumed were recorded at their carrying values as of the respective date of acquisition, as their carrying values approximated their fair values due to their short-term nature. The fair values of goodwill and other intangible assets acquired in our acquisition of America’s 1st Choice were internally estimated based on the income approach. The income approach estimates fair value based on the present value of the cash flows that the assets could be expected to generate in the future. We developed internal estimates for the expected cash flows and discount rate in the present value calculation. Other than the assets acquired and liabilities assumed in our acquisition of America’s 1st Choice described above, there were no material assets or liabilities measured at fair value on a nonrecurring basis during the three and nine months ended September 30, 2019 or 2018 . Our valuation policy is determined by members of our treasury and accounting departments. Whenever possible, our policy is to obtain quoted market prices in active markets to estimate fair values for recognition and disclosure purposes. Where quoted market prices in active markets are not available, fair values are estimated using discounted cash flow analyses, broker quotes or other valuation techniques. These techniques are significantly affected by our assumptions, including discount rates and estimates of future cash flows. Potential taxes and other transaction costs are not considered in estimating fair values. Our valuation policy is generally to obtain quoted prices for each security from third party pricing services, which are derived through recently reported trades for identical or similar securities making adjustments through the reporting date based upon available market observable information. As we are responsible for the determination of fair value, we perform a monthly analysis on the prices received from the pricing services to determine whether the prices are reasonable estimates of fair value. This analysis is performed by our internal treasury personnel who are familiar with our investment portfolios, the pricing services engaged and the valuation techniques and inputs used. Our analysis includes procedures such as a review of month-to-month price fluctuations and price comparisons to secondary pricing services. There were no adjustments to quoted market prices obtained from the pricing services during the three and nine months ended September 30, 2019 or 2018 . In addition to the preceding disclosures on assets recorded at fair value in the consolidated balance sheets, FASB guidance also requires the disclosure of fair values for certain other financial instruments for which it is practicable to estimate fair value, whether or not such values are recognized in our consolidated balance sheets. Non-financial instruments such as real estate, property and equipment, other current assets, deferred income taxes, intangible assets and certain financial instruments, such as policy liabilities, are excluded from the fair value disclosures. Therefore, the fair value amounts cannot be aggregated to determine our underlying economic value. The carrying amounts reported in our consolidated balance sheets for cash and cash equivalents, accrued investment income, premium receivables, self-funded receivables, other receivables, income taxes receivable/payable, unearned income, accounts payable and accrued expenses, security trades pending payable, securities lending payable and certain other current liabilities approximate fair value because of the short term nature of these items. These assets and liabilities are not listed in the table below. The following methods and assumptions were used to estimate the fair value of each class of financial instrument that is recorded at its carrying value in our consolidated balance sheets: Other invested assets, long-term: Other invested assets, long-term include primarily our investments in limited partnerships, joint ventures and other non-controlled corporations, as well as the cash surrender value of corporate-owned life insurance policies. Investments in limited partnerships, joint ventures and other non-controlled corporations are carried at our share in the entities’ undistributed earnings, which approximates fair value. The carrying value of corporate-owned life insurance policies represents the cash surrender value as reported by the respective insurer, which approximates fair value. Short-term borrowings: The fair value of our short-term borrowings is based on quoted market prices for the same or similar debt, or, if no quoted market prices were available, on the current market interest rates estimated to be available to us for debt of similar terms and remaining maturities. Long-term debt – commercial paper: The carrying amount for commercial paper approximates fair value, as the underlying instruments have variable interest rates at market value. Long-term debt – senior unsecured notes and surplus notes: The fair values of our notes are based on quoted market prices in active markets for the same or similar debt, or, if no quoted market prices are available, on the current market observable rates estimated to be available to us for debt of similar terms and remaining maturities. Long-term debt – convertible debentures: The fair value of our convertible debentures is based on the quoted market price in the active private market in which the convertible debentures trade. A summary of the estimated fair values by level of each class of financial instrument that is recorded at its carrying value on our consolidated balance sheets at September 30, 2019 and December 31, 2018 is as follows: Carrying Value Estimated Fair Value Level I Level II Level III Total September 30, 2019 Assets: Other invested assets, long-term $ 3,914 $ — $ — $ 3,914 $ 3,914 Liabilities: Debt: Short-term borrowings 710 — 710 — 710 Commercial paper 500 — 500 — 500 Notes 18,841 — 20,198 — 20,198 Convertible debentures 179 — 893 — 893 December 31, 2018 Assets: Other invested assets, long-term $ 3,726 $ — $ — $ 3,726 $ 3,726 Liabilities: Debt: Short-term borrowings 1,145 — 1,145 — 1,145 Commercial paper 697 — 697 — 697 Notes 17,178 — 17,145 — 17,145 Convertible debentures 191 — 1,030 — 1,030

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes During the three months ended September 30, 2019 and 2018 , we recognized income tax expense of $306 and $282 , respectively, which represent effective tax rates of 20.6% and 22.7% , respectively. The increase in income tax expense was primarily due to the 2018 remeasurement of deferred tax assets and liabilities against the prior year provisional estimates as required by the Tax Cuts and Jobs Act. The increase in income tax expense was partially offset by the suspension of the non-tax deductible Health Insurance Provider Fee, or HIP Fee, for 2019, which resulted in a decrease in income tax expense of $76 . The decrease in the effective tax rate was primarily due to the suspension of the non-tax deductible HIP Fee for 2019. During the nine months ended September 30, 2019 and 2018 , we recognized income tax expense of $1,014 and $1,200 , respectively, which represent effective tax rates of 20.7% and 26.5% , respectively. The decrease in income tax expense and effective tax rate was primarily due to the suspension of the non-tax deductible HIP Fee for 2019, which resulted in a decrease in income tax expense of $243 .

Retirement Benefits

Retirement Benefits	9 Months Ended
	Sep. 30, 2019
Defined Benefit Plan [Abstract]
Retirement Benefits	Retirement Benefits The components of net periodic benefit credit included in our consolidated statements of income for the three months ended September 30, 2019 and 2018 are as follows: Pension Benefits Other Benefits Three Months Ended Three Months Ended 2019 2018 2019 2018 Service cost $ — $ 2 $ 1 $ — Interest cost 15 14 3 4 Expected return on assets (35 ) (37 ) (6 ) (6 ) Recognized actuarial loss 5 6 1 1 Settlement loss 4 6 — — Amortization of prior service credit — — (3 ) (3 ) Net periodic benefit credit $ (11 ) $ (9 ) $ (4 ) $ (4 ) The components of net periodic benefit credit included in our consolidated statements of income for the nine months ended September 30, 2019 and 2018 are as follows: Pension Benefits Other Benefits Nine Months Ended Nine Months Ended 2019 2018 2019 2018 Service cost $ — $ 6 $ 1 $ 1 Interest cost 47 41 11 11 Expected return on assets (104 ) (110 ) (17 ) (18 ) Recognized actuarial loss 13 18 2 3 Settlement loss 8 19 — — Amortization of prior service credit — — (9 ) (9 ) Net periodic benefit credit $ (36 ) $ (26 ) $ (12 ) $ (12 ) For the year ending December 31, 2019 , no material contributions are expected to be necessary to meet the Employee Retirement Income Security Act of 1974, as amended, or ERISA, required funding levels; however, we may elect to make discretionary contributions up to the maximum amount deductible for income tax purposes. Contributions of $0 and $7 were made to our retirement benefit plans during the nine months ended September 30, 2019 and 2018 .

Medical Claims Payable

Medical Claims Payable	9 Months Ended
	Sep. 30, 2019
Liability for Claims and Claims Adjustment Expense [Abstract]
Medical Claims payable	Medical Claims Payable A reconciliation of the beginning and ending balances for medical claims payable, by segment (see Note 15, “Segment Information”), for the nine months ended September 30, 2019 is as follows: Commercial & Specialty Business Government Business Total Gross medical claims payable, beginning of period $ 2,586 $ 4,680 $ 7,266 Ceded medical claims payable, beginning of period (10 ) (24 ) (34 ) Net medical claims payable, beginning of period 2,576 4,656 7,232 Net incurred medical claims: Current period 18,986 39,171 58,157 Prior periods redundancies (162 ) (275 ) (437 ) Total net incurred medical claims 18,824 38,896 57,720 Net payments attributable to: Current period medical claims 16,277 33,474 49,751 Prior periods medical claims 2,213 4,253 6,466 Total net payments 18,490 37,727 56,217 Net medical claims payable, end of period 2,910 5,825 8,735 Ceded medical claims payable, end of period 8 27 35 Gross medical claims payable, end of period $ 2,918 $ 5,852 $ 8,770 At September 30, 2019 , the total of net incurred but not reported liabilities plus expected development on reported claims for the Commercial & Specialty Business was $30 , $171 and $2,709 for the claim years 2017 and prior, 2018 and 2019, respectively. At September 30, 2019 , the total of net incurred but not reported liabilities plus expected development on reported claims for the Government Business was $23 , $105 and $5,697 for the claim years 2017 and prior, 2018 and 2019, respectively. A reconciliation of the beginning and ending balances for medical claims payable, by segment (see Note 15, “Segment Information”), for the nine months ended September 30, 2018 is as follows: Commercial & Specialty Business Government Business Total Gross medical claims payable, beginning of period $ 3,383 $ 4,431 $ 7,814 Ceded medical claims payable, beginning of period (78 ) (27 ) (105 ) Net medical claims payable, beginning of period 3,305 4,404 7,709 Business combinations and purchase adjustments — 199 199 Net incurred medical claims: Current period 17,732 33,664 51,396 Prior periods redundancies (424 ) (434 ) (858 ) Total net incurred medical claims 17,308 33,230 50,538 Net payments attributable to: Current period medical claims 15,275 29,236 44,511 Prior periods medical claims 2,671 3,833 6,504 Total net payments 17,946 33,069 51,015 Net medical claims payable, end of period 2,667 4,764 7,431 Ceded medical claims payable, end of period 10 27 37 Gross medical claims payable, end of period $ 2,677 $ 4,791 $ 7,468 The reconciliation of net incurred medical claims to benefit expense included in our consolidated statements of income for periods in 2019 are as follows: Three Months Ended Nine Months Ended March 31, 2019 June 30, 2019 September 30, 2019 Net incurred medical claims: Commercial & Specialty Business $ 5,856 $ 6,422 $ 6,546 $ 18,824 Government Business 12,483 13,062 13,351 38,896 Total net incurred medical claims 18,339 19,484 19,897 57,720 Quality improvement and other claims expense 943 884 856 2,683 Benefit expense $ 19,282 $ 20,368 $ 20,753 $ 60,403 Net incurred medical claims for the three months ended March 31, 2019 and June 30, 2019 in the table above include a reclassification between the Commercial and Specialty Business and Government Business segments to adjust certain intercompany eliminations. This reclassification did not impact any other amounts presented in the consolidated financial statements. The reconciliation of net incurred medical claims to benefit expense included in our consolidated statements of income for periods in 2018 are as follows: Three Months Ended Nine Months Ended March 31, 2018 June 30, 2018 September 30, 2018 Net incurred medical claims: Commercial & Specialty Business $ 5,410 $ 5,884 $ 6,014 $ 17,308 Government Business 10,794 11,039 11,397 33,230 Total net incurred medical claims 16,204 16,923 17,411 50,538 Quality improvement and other claims expense 842 805 774 2,421 Benefit expense $ 17,046 $ 17,728 $ 18,185 $ 52,959 The reconciliation of the medical claims payable reflected in the tables above to the consolidated ending balance for medical claims payable included in the consolidated balance sheet, as of September 30, 2019 , is as follows: Commercial & Specialty Business Government Business Total Net medical claims payable, end of period $ 2,910 $ 5,825 $ 8,735 Ceded medical claims payable, end of period 8 27 35 Insurance lines other than short duration — 207 207 Gross medical claims payable, end of period $ 2,918 $ 6,059 $ 8,977

Debt

Debt	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt	Debt We generally issue senior unsecured notes for long-term borrowing purposes. At September 30, 2019 and December 31, 2018 , we had $18,816 and $17,153 , respectively, outstanding under these notes. On September 9, 2019, we issued $850 aggregate principal amount of 2.375% Notes due 2025, or the 2025 Notes, $825 aggregate principal amount of 2.875% Notes due 2029, or the 2029 Notes, and $825 aggregate principal amount of 3.700% Notes due 2049, or the 2049 Notes, under our shelf registration statement. Interest on the 2025 Notes is payable semi-annually in arrears on January 15 and July 15 of each year, commencing January 15, 2020. Interest on the 2029 Notes and the 2049 Notes is payable semi-annually in arrears on March 15 and September 15 each year, commencing March 15, 2020. The proceeds are being used for working capital and general corporate purposes, including, but not limited to, the repurchase of our common stock pursuant to our share repurchase program, repayment of short-term and long-term debt and to fund acquisitions. On May 1, 2018, we settled each of the Equity Units stock purchase contracts at a settlement rate of 0.2412 shares of our common stock, using a market value formula set forth in the Equity Units purchase contracts. This resulted in the issuance of approximately 6.0 shares. We had issued 25 Equity Units on May 12, 2015, pursuant to an underwriting agreement dated May 6, 2015, in an aggregate principal amount of $1,250 . Each Equity Unit had a stated amount of $50 (whole dollars) and consisted of a purchase contract obligating the holder to purchase a certain number of shares of our common stock on May 1, 2018, subject to earlier termination or settlement, for a price in cash of $50 (whole dollars); and a 5% undivided beneficial ownership interest in $1,000 (whole dollars) principal amount of our 1.900% remarketable subordinated notes, or RSNs, due 2028. On March 2, 2018, we remarketed the RSNs and used the proceeds to purchase U.S. Treasury securities that were pledged to secure the stock purchase obligations of the holders of the Equity Units. The purchasers of the RSNs transferred the RSNs to us in exchange for $1,250 principal amount of our 4.101% senior notes due 2028, or the 2028 Notes, and a cash payment of $4 . We cancelled the RSNs upon receipt and recognized a loss on extinguishment of debt of $18 . At the remarketing, we also issued $850 aggregate principal amount of 4.550% notes due 2048, or the 2048 Notes, under our shelf registration statement. We used the proceeds from the 2048 Notes for working capital and general corporate purposes. Interest on the 2028 Notes and the 2048 Notes is payable semi-annually in arrears on March 1 and September 1 of each year, commencing on September 1, 2018. We have an unsecured surplus note with an outstanding principal balance of $25 at both September 30, 2019 and December 31, 2018 . We have a senior revolving credit facility, or the 5-Year Facility, with a group of lenders for general corporate purposes. In June 2019, we amended and restated the credit agreement for the 5-Year Facility to, among other things, extend the maturity date of the 5-Year Facility from August 2020 to June 2024 and decreased the amount of credit available under the 5-Year Facility from $3,500 to $2,500 . In June 2019, we also entered into a 364-day senior revolving credit facility, or 364-Day Facility, with a group of lenders for general corporate purposes, which provides for credit in the amount of $1,000 and matures in June 2020. There were no amounts outstanding under the 5-Year Facility or the 364-Day Facility at any time during the nine months ended September 30, 2019 or under the 5-Year Facility at December 31, 2018 . Through certain subsidiaries, we have entered into multiple 364-day lines of credit, or the Subsidiary Credit Facilities, with separate lenders for general corporate purposes. The Subsidiary Credit Facilities provide combined credit of up to $600 . At September 30, 2019 and December 31, 2018 , $150 and $500 , respectively, were outstanding under our Subsidiary Credit Facilities. We have an authorized commercial paper program of up to $3,500 , the proceeds of which may be used for general corporate purposes. In August 2019, we increased the amount available under the commercial paper program from $2,500 to $3,500 . At September 30, 2019 and December 31, 2018 , we had $500 and $697 , respectively, outstanding under this program. We have outstanding senior unsecured convertible debentures due 2042, or the Debentures, which are governed by an indenture between us and The Bank of New York Mellon Trust Company, N.A., as trustee, or the indenture. We have accounted for the Debentures in accordance with the FASB cash conversion guidance for debt with conversion and other options. As a result, the value of the embedded conversion option (net of deferred taxes and equity issuance costs) has been bifurcated from its debt host and recorded as a component of additional paid-in capital in our consolidated balance sheets. During the nine months ended September 30, 2019 , $20 aggregate principal amount of the Debentures were surrendered for conversion by certain holders in accordance with the terms and provisions of the indenture. We elected to settle the excess of the principal amount of the conversions with cash for total payments of $73 . We recognized a gain of $1 on the extinguishment of debt related to the Debentures, based on the fair values of the debt on the conversion settlement dates. The following table summarizes at September 30, 2019 the related balances, conversion rate and conversion price of the Debentures: Outstanding principal amount $ 267 Unamortized debt discount $ 85 Net debt carrying amount $ 179 Equity component carrying amount $ 97 Conversion rate (shares of common stock per $1,000 of principal amount) 13.9250 Effective conversion price (per $1,000 of principal amount) $ 71.8129 We are a member, through certain subsidiaries, of the Federal Home Loan Bank of Indianapolis, the Federal Home Loan Bank of Cincinnati and the Federal Home Loan Bank of Atlanta, or collectively, the FHLBs. As a member we have the ability to obtain short-term cash advances, subject to certain minimum collateral requirements. We had $560 and $645 in outstanding short-term borrowings from FHLBs, at September 30, 2019 and December 31, 2018 with fixed interest rates of 1.990% and 2.458% respectively. All debt is a direct obligation of Anthem, Inc., except for the surplus note, the FHLB borrowings, and the Subsidiary Credit Facilities.

Commitments And Contingencies

Commitments And Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	Commitments and Contingencies Litigation and Regulatory Proceedings In the ordinary course of business, we are defendants in, or parties to, a number of pending or threatened legal actions or proceedings. To the extent a plaintiff or plaintiffs in the following cases have specified in their complaint or in other court filings the amount of damages being sought, we have noted those alleged damages in the descriptions below. With respect to the cases described below, we contest liability and/or the amount of damages in each matter and believe we have meritorious defenses. Where available information indicates that it is probable that a loss has been incurred as of the date of the consolidated financial statements and we can reasonably estimate the amount of that loss, we accrue the estimated loss by a charge to income. In many proceedings, however, it is difficult to determine whether any loss is probable or reasonably possible. In addition, even where loss is possible or an exposure to loss exists in excess of the liability already accrued with respect to a previously identified loss contingency, it is not always possible to reasonably estimate the amount of the possible loss or range of loss. With respect to many of the proceedings to which we are a party, we cannot provide an estimate of the possible losses, or the range of possible losses in excess of the amount, if any, accrued, for various reasons, including but not limited to some or all of the following: (i) there are novel or unsettled legal issues presented, (ii) the proceedings are in early stages, (iii) there is uncertainty as to the likelihood of a class being certified or decertified or the ultimate size and scope of the class, (iv) there is uncertainty as to the outcome of pending appeals or motions, (v) there are significant factual issues to be resolved, and/or (vi) in many cases, the plaintiffs have not specified damages in their complaint or in court filings. For those legal proceedings where a loss is probable, or reasonably possible, and for which it is possible to reasonably estimate the amount of the possible loss or range of losses, we currently believe that the range of possible losses, in excess of established reserves is, in the aggregate, from $0 to approximately $700 at September 30, 2019 . This estimated aggregate range of reasonably possible losses is based upon currently available information taking into account our best estimate of such losses for which such an estimate can be made. Blue Cross Blue Shield Antitrust Litigation We are a defendant in multiple lawsuits that were initially filed in 2012 against the BCBSA and Blue Cross and/or Blue Shield licensees, or Blue plans, across the country. The cases were consolidated into a single multi-district proceeding captioned In re Blue Cross Blue Shield Antitrust Litigation that is pending in the United States District Court for the Northern District of Alabama, or the Court. Generally, the suits allege that the BCBSA and the Blue plans have conspired to horizontally allocate geographic markets through license agreements, best efforts rules that limit the percentage of non-Blue revenue of each plan, restrictions on acquisitions rules governing the BlueCard and National Accounts programs and other arrangements in violation of the Sherman Antitrust Act, or Sherman Act, and related state laws. The cases were brought by two putative nationwide classes of plaintiffs, health plan subscribers and providers, and actions filed in twenty-eight states have been consolidated into the multi-district proceeding. In response to cross motions for partial summary judgment by plaintiffs and defendants, the Court issued an order in April 2018 determining that the defendants’ aggregation of geographic market allocations and output restrictions are to be analyzed under a per se standard of review, and the BlueCard program and other alleged Section 1 Sherman Act violations are to be analyzed under the rule of reason standard of review. The Court also found that there remain genuine issues of material fact as to whether defendants operate as a single entity with regard to the enforcement of the Blue Cross Blue Shield trademarks. No dates have been set for either the final pretrial conferences or trials in these actions. In March 2019, the Court issued a Fourth Amended Scheduling Order requiring that briefing on motions for class certification and related expert reports, merits and damages expert reports, and certain dispositive motions occur in 2019. In April 2019, plaintiffs filed their motions for class certification in conjunction with their supporting expert reports. Defendants filed their motions to exclude plaintiffs’ experts, as well as their opposition to plaintiffs’ motions for class certification, in July 2019. The case has been stayed until January 2020. We intend to vigorously defend these suits; however, their ultimate outcome cannot be presently determined. Blue Cross of California Taxation Litigation In July 2013, our California affiliate Blue Cross of California (doing business as Anthem Blue Cross), or BCC, was named as a defendant in a California taxpayer action filed in Los Angeles County Superior Court, captioned Michael D. Myers v. State Board of Equalization, et al. This action was brought under a California statute that permits an individual taxpayer to sue a governmental agency when the taxpayer believes the agency has failed to enforce governing law. Plaintiff contends that BCC, a licensed Health Care Service Plan, or HCSP, is an “insurer” for purposes of taxation despite acknowledging it is not an “insurer” under regulatory law. At the time, under California law, “insurers” were required to pay a gross premiums tax, or GPT, calculated as 2.35% on gross premiums. As a licensed HCSP, BCC has paid the California Corporate Franchise Tax, or CFT, the tax paid by California businesses generally. Plaintiff contends that BCC must pay the GPT rather than the CFT, and seeks a writ of mandate directing the taxing agencies to collect the GPT and an order requiring BCC to pay GPT back taxes, interest, and penalties for the eight-year period prior to the filing of the complaint. In March 2018, the Superior Court denied BCC’s motion for judgment on the pleadings and similar motions brought by other entities. We filed a writ of mandate in the California Court of Appeal. Although the California Court of Appeal initially accepted our writ, it later indicated that it will not hear the issues raised by our writ until the case concludes in the Superior Court. The Superior Court has scheduled trial for March 23, 2020. The parties are currently engaged in discovery and are in the process of retaining experts. Because GPT is constitutionally imposed in lieu of certain other taxes, BCC has filed protective tax refund claims with the City of Los Angeles, the California Department of Health Care Services and the Franchise Tax Board to protect its rights to recover certain taxes previously paid should BCC eventually be determined to be subject to the GPT for the tax periods at issue in the litigation. BCC intends to vigorously defend this suit; however, its ultimate outcome cannot be presently determined. Express Scripts, Inc. Pharmacy Benefit Management Litigation In March 2016, we filed a lawsuit against Express Scripts, Inc., or Express Scripts, our vendor for pharmacy benefit management, or PBM, services, captioned Anthem, Inc. v. Express Scripts, Inc. , in the U.S. District Court for the Southern District of New York. The lawsuit seeks to recover over $14,800 in damages for pharmacy pricing that is higher than competitive benchmark pricing under the agreement between the parties, or ESI PBM Agreement, over $158 in damages related to operational breaches, as well as various declarations under the ESI PBM Agreement between the parties, including that Express Scripts: (i) breached its obligation to negotiate in good faith and to agree in writing to new pricing terms; (ii) is required to provide competitive benchmark pricing to us through the term of the ESI PBM Agreement; (iii) has breached the ESI PBM Agreement; and (iv) is required under the ESI PBM Agreement to provide post-termination services, at competitive benchmark pricing, for one year following any termination. Express Scripts has disputed our contractual claims and is seeking declaratory judgments: (i) regarding the timing of the periodic pricing review under the ESI PBM Agreement; and (ii) that it has no obligation to ensure that we receive any specific level of pricing, that we have no contractual right to any change in pricing under the ESI PBM Agreement and that its sole obligation is to negotiate proposed pricing terms in good faith. In the alternative, Express Scripts claims that we have been unjustly enriched by its payment of $4,675 at the time we entered into the ESI PBM Agreement. In March 2017, the court granted our motion to dismiss Express Scripts’ counterclaims for (i) breach of the implied covenant of good faith and fair dealing, and (ii) unjust enrichment with prejudice. The only remaining claims are for breach of contract and declaratory relief. Discovery is scheduled to be completed in December 2019. We intend to vigorously pursue our claims and defend against any counterclaims, which we believe are without merit; however, the ultimate outcome cannot be presently determined. In re Express Scripts/Anthem ERISA Litigation We are a defendant in a class action lawsuit that was initially filed in June 2016 against Anthem, Inc. and Express Scripts, which has been consolidated into a single multi-district lawsuit captioned In Re Express Scripts/Anthem ERISA Litigation, in the U.S. District Court for the Southern District of New York. The consolidated complaint was filed by plaintiffs against Express Scripts and us on behalf of all persons who are participants in or beneficiaries of any ERISA or non-ERISA healthcare plan from December 1, 2009 to the present in which we provided prescription drug benefits through the ESI PBM Agreement and paid a percentage based co-insurance payment in the course of using that prescription drug benefit. The plaintiffs allege that we breached our duties, either under ERISA or with respect to the implied covenant of good faith and fair dealing implied in the health plans, (i) by failing to adequately monitor Express Scripts’ pricing under the ESI PBM Agreement and (ii) by placing our own pecuniary interest above the best interests of our insureds by allegedly agreeing to higher pricing in the ESI PBM Agreement in exchange for the purchase price for our NextRx PBM business, and (iii) with respect to the non-ERISA members, by negotiating and entering into the ESI PBM Agreement that was allegedly detrimental to the interests of such non-ERISA members. Plaintiffs seek to hold us and Express Scripts jointly and severally liable and to recover all losses suffered by the proposed class, equitable relief, disgorgement of alleged ill-gotten gains, injunctive relief, attorney’s fees and costs and interest. In April 2017, we filed a motion to dismiss the claims brought against us, and it was granted, without prejudice, in January 2018. Plaintiffs filed a notice of appeal with the United States Court of Appeals for the Second Circuit, which was heard in October 2018 but has not yet been decided. We intend to vigorously defend this suit; however, its ultimate outcome cannot be presently determined. Cigna Corporation Merger Litigation In July 2015, we and Cigna Corporation, or Cigna, announced that we entered into the Agreement and Plan of Merger, or Cigna Merger Agreement, pursuant to which we would acquire all outstanding shares of Cigna. In July 2016, the U.S. Department of Justice, or DOJ, along with certain state attorneys general, filed a civil antitrust lawsuit in the U.S. District Court for the District of Columbia, or District Court, seeking to block the merger. In February 2017, Cigna purported to terminate the Cigna Merger Agreement and commenced litigation against us in the Delaware Court of Chancery, or Delaware Court, seeking damages, including the $1,850 termination fee pursuant to the terms of the Cigna Merger Agreement, and a declaratory judgment that its purported termination of the Cigna Merger Agreement was lawful, among other claims, which is captioned Cigna Corp. v. Anthem Inc. Also in February 2017, we initiated our own litigation against Cigna in the Delaware Court seeking a temporary restraining order to enjoin Cigna from terminating the Cigna Merger Agreement, specific performance compelling Cigna to comply with the Cigna Merger Agreement and damages, which is captioned Anthem Inc. v. Cigna Corp . In April 2017, the U.S. Circuit Court of Appeals for the District of Columbia affirmed the ruling of the District Court, which blocked the merger. In May 2017, after the Delaware Court denied our motion to enjoin Cigna from terminating the Cigna Merger Agreement, we delivered to Cigna a notice terminating the Cigna Merger Agreement. In the Delaware Court litigation, trial commenced in late February 2019 and concluded in March 2019. The Delaware Court has set closing argument for November 25, 2019. We believe Cigna’s allegations are without merit and we intend to vigorously pursue our claims and defend against Cigna’s allegations; however, the ultimate outcome of our litigation with Cigna cannot be presently determined. In October 2018, a shareholder filed a derivative lawsuit in the State of Indiana Marion County Superior Court, captioned Henry Bittmann, Derivatively, et al. v. Joseph R Swedish, et al. , purportedly on behalf of us and our shareholders against certain current and former directors and officers alleging breaches of fiduciary duties, unjust enrichment and corporate waste associated with the Cigna Merger Agreement. This case has been stayed at the request of the parties pending the outcome of our litigation with Cigna in the Delaware Court. This lawsuit’s ultimate outcome cannot be presently determined. U.S. Department of Justice (DOJ) Civil Investigative Demands Beginning in December 2016, the DOJ has issued civil investigative demands to us to discover information about our chart review and risk adjustment programs under Parts C and D of the Medicare Program. We understand the DOJ is investigating the programs of other Medicare Advantage health plans, along with providers and vendors. We continue to cooperate with the DOJ’s investigation, and the ultimate outcome cannot presently be determined. Cyber Attack Regulatory Proceedings and Litigation In February 2015, we reported that we were the target of a sophisticated external cyber attack. The attackers gained unauthorized access to certain of our information technology systems and obtained personal information related to many individuals and employees, such as names, birth dates, healthcare identification/social security numbers, street addresses, email addresses, phone numbers and employment information, including income data. To date, there is no evidence that credit card or medical information, such as claims, test results or diagnostic codes, were targeted, accessed or obtained, although no assurance can be given that we will not identify additional information that was accessed or obtained. Upon discovery of the cyber attack, we took immediate action to remediate the security vulnerability and retained a cybersecurity firm to evaluate our systems and identify solutions based on the evolving landscape. We have provided credit monitoring and identity protection services to those who have been affected by this cyber attack. We have continued to implement security enhancements since this incident. We have incurred expenses subsequent to the cyber attack to investigate and remediate this matter and expect to continue to incur expenses of this nature in the foreseeable future. We recognize these expenses in the periods in which they are incurred. Federal and state agencies, including state insurance regulators, state attorneys general, the Health and Human Services Office of Civil Rights and the Federal Bureau of Investigation, are investigating, or have investigated, events related to the cyber attack, including how it occurred, its consequences and our responses. The investigations have all been resolved with the exception of an ongoing investigation by a multi-state group of attorneys general, which remains outstanding. Although we are cooperating in this investigation, we may be subject to additional fines or other obligations. We intend to vigorously defend the remaining regulatory investigation; however, its ultimate outcome cannot be presently determined. We have contingency plans and insurance coverage for certain expenses and potential liabilities of this nature and will pursue coverage for all applicable losses; however, the ultimate outcome of our pursuit of insurance coverage cannot be presently determined. Other Contingencies From time to time, we and certain of our subsidiaries are parties to various legal proceedings, many of which involve claims for coverage encountered in the ordinary course of business. We, like HMOs and health insurers generally, exclude certain healthcare and other services from coverage under our HMO, PPO and other plans. We are, in the ordinary course of business, subject to the claims of our enrollees arising out of decisions to restrict or deny reimbursement for uncovered services. The loss of even one such claim, if it results in a significant punitive damage award, could have a material adverse effect on us. In addition, the risk of potential liability under punitive damage theories may increase significantly the difficulty of obtaining reasonable reimbursement of coverage claims. In addition to the lawsuits described above, we are also involved in other pending and threatened litigation of the character incidental to our business, and are from time to time involved as a party in various governmental investigations, audits, reviews and administrative proceedings. These investigations, audits, reviews and administrative proceedings include routine and special inquiries by state insurance departments, state attorneys general, the U.S. Attorney General and subcommittees of the U.S. Congress. Such investigations, audits, reviews and administrative proceedings could result in the imposition of civil or criminal fines, penalties, other sanctions and additional rules, regulations or other restrictions on our business operations. Any liability that may result from any one of these actions, or in the aggregate, could have a material adverse effect on our consolidated financial position or results of operations. Contractual Obligations and Commitments Express Scripts, through our ESI PBM Agreement, is the provider of certain PBM services to our plans. In October 2017, we established a new pharmacy benefits manager, called IngenioRx, and entered into a five-year agreement with CaremarkPCS Health, L.L.C., or CVS Health, which is a subsidiary of CVS Health Corporation, to begin offering PBM solutions, or the CVS PBM Agreement. In January 2019, we exercised our contractual right to terminate the ESI PBM Agreement earlier than the original expiration date of December 31, 2019 due to the recent acquisition of Express Scripts by Cigna. As a result of exercising our early termination right, the ESI PBM Agreement terminated on March 1, 2019, and on March 2, 2019, the twelve-month transition period to migrate the services from Express Scripts began. CVS Health began providing certain PBM services to IngenioRx pursuant to the CVS PBM Agreement in the second quarter of 2019. Notwithstanding our termination of the ESI PBM Agreement, the litigation between us and Express Scripts regarding the ESI PBM Agreement continues. For additional information regarding this lawsuit, refer to the Litigation and Regulatory Proceedings-Express Scripts, Inc. Pharmacy Benefit Management Litigation section above. We believe we have appropriately recognized all rights and obligations under the ESI PBM Agreement as of September 30, 2019 .

Capital Stock

Capital Stock	9 Months Ended
	Sep. 30, 2019
Capital [Abstract]
Capital Stock	Capital Stock Use of Capital – Dividends and Stock Repurchase Program We regularly review the appropriate use of capital, including acquisitions, common stock and debt security repurchases and dividends to shareholders. The declaration and payment of any dividends or repurchases of our common stock or debt is at the discretion of our Board of Directors and depends upon our financial condition, results of operations, future liquidity needs, regulatory and capital requirements and other factors deemed relevant by our Board of Directors. A summary of the cash dividend activity for the nine months ended September 30, 2019 and 2018 is as follows: Declaration Date Record Date Payment Date Cash Dividend per Share Total Nine Months Ended September 30, 2019 January 29, 2019 March 18, 2019 March 29, 2019 $0.80 $ 206 April 23, 2019 June 10, 2019 June 25, 2019 $0.80 $ 206 July 23, 2019 September 10, 2019 September 25, 2019 $0.80 $ 204 Nine Months Ended September 30, 2018 January 30, 2018 March 9, 2018 March 23, 2018 $0.75 $ 192 April 24, 2018 June 8, 2018 June 25, 2018 $0.75 $ 196 July 24, 2018 September 10, 2018 September 25, 2018 $0.75 $ 195 On October 22, 2019, our Audit Committee declared a fourth quarter 2019 dividend to shareholders of $0.80 per share, payable on December 20, 2019 to shareholders of record at the close of business on December 5, 2019 . Under our Board of Directors’ authorization, we maintain a common stock repurchase program. On December 7, 2017, the Board of Directors authorized a $5,000 increase to the common stock repurchase program. Repurchases may be made from time to time at prevailing market prices, subject to certain restrictions on volume, pricing and timing. The repurchases are effected from time to time in the open market, through negotiated transactions, including accelerated share repurchase agreements, and through plans designed to comply with Rule 10b5-1 under the Securities Exchange Act of 1934, as amended. Our stock repurchase program is discretionary, as we are under no obligation to repurchase shares. We repurchase shares under the program when we believe it is a prudent use of capital. The excess cost of the repurchased shares over par value is charged on a pro rata basis to additional paid-in capital and retained earnings. A summary of common stock repurchases from October 1, 2019 through October 16, 2019 (subsequent to September 30, 2019 ) and for the nine months ended September 30, 2019 and 2018 is as follows: October 1, 2019 Nine Months Ended September 30 2019 2018 Shares repurchased 0.4 5.2 5.0 Average price per share $ 238.71 $ 270.42 $ 240.15 Aggregate cost $ 104 $ 1,396 $ 1,192 Authorization remaining at the end of the period $ 3,994 $ 4,098 $ 5,986 For additional information regarding the use of capital for debt security repurchases, see Note 10, “Debt” of this Form 10-Q and Note 12, “Debt,” to our audited consolidated financial statements as of and for the year ended December 31, 2018 included in our 2018 Annual Report on Form 10-K. Stock Incentive Plan s A summary of stock option activity for the nine months ended September 30, 2019 is as follows: Number of Shares Weighted- Average Option Price per Share Weighted- Average Remaining Contractual Life (Years) Aggregate Intrinsic Value Outstanding at January 1, 2019 3.7 $ 149.65 Granted 0.7 306.74 Exercised (0.9 ) 127.92 Forfeited or expired (0.1 ) 238.81 Outstanding at September 30, 2019 3.4 185.47 6.28 $ 233 Exercisable at September 30, 2019 2.2 142.26 5.02 $ 220 A summary of the nonvested restricted stock activity, including restricted stock units, for the nine months ended September 30, 2019 is as follows: Restricted Stock Shares and Units Weighted- Average Grant Date Fair Value per Share Nonvested at January 1, 2019 1.7 $ 183.32 Granted 0.5 306.13 Vested (0.8 ) 152.97 Forfeited — 243.77 Nonvested at September 30, 2019 1.4 240.92 During the nine months ended September 30, 2019 , we granted approximately 0.2 restricted stock units that are contingent upon us achieving earnings targets over the three year period from 2019 to 2021. These grants have been included in the activity shown above, but will be subject to adjustment at the end of 2021 based on results in the three year period. Fair Value We use a binomial lattice valuation model to estimate the fair value of all stock options granted. For a more detailed discussion of our stock incentive plan fair value methodology, see Note 14, “Capital Stock,” to our audited consolidated financial statements as of and for the year ended December 31, 2018 included in our 2018 Annual Report on Form 10-K. The following weighted-average assumptions were used to estimate the fair values of options granted during the nine months ended September 30, 2019 and 2018 : Nine Months Ended September 30 2019 2018 Risk-free interest rate 2.69 % 2.90 % Volatility factor 25.00 % 30.00 % Quarterly dividend yield 0.260 % 0.323 % Weighted-average expected life (years) 4.40 3.70 The following weighted-average fair values per option or share were determined for the nine months ended September 30, 2019 and 2018 : Nine Months Ended September 30 2019 2018 Options granted during the period $ 68.69 $ 55.44 Restricted stock awards granted during the period 306.13 233.27

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 30, 2019
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss A reconciliation of the components of accumulated other comprehensive loss at September 30, 2019 and 2018 is as follows: September 30 2019 2018 Investments, excluding non-credit component of other-than-temporary impairments: Gross unrealized gains $ 770 $ 170 Gross unrealized losses (54 ) (289 ) Net pre-tax unrealized gains (losses) 716 (119 ) Deferred tax (liability) asset (164 ) 24 Net unrealized gains (losses) on investments 552 (95 ) Non-credit components of other-than-temporary impairments on investments: Unrealized losses (5 ) (2 ) Deferred tax asset 1 — Net unrealized non-credit component of other-than-temporary impairments on investments (4 ) (2 ) Cash flow hedges: Gross unrealized losses (340 ) (315 ) Deferred tax asset 63 66 Net unrealized losses on cash flow hedges (277 ) (249 ) Defined benefit pension plans: Deferred net actuarial loss (730 ) (587 ) Deferred prior service credits (1 ) (1 ) Deferred tax asset 188 153 Net unrecognized periodic benefit costs for defined benefit pension plans (543 ) (435 ) Postretirement benefit plans: Deferred net actuarial loss (57 ) (75 ) Deferred prior service costs 25 37 Deferred tax asset 8 10 Net unrecognized periodic benefit costs for postretirement benefit plans (24 ) (28 ) Foreign currency translation adjustments: Gross unrealized losses (4 ) (2 ) Deferred tax asset 1 — Net unrealized losses on foreign currency translation adjustments (3 ) (2 ) Accumulated other comprehensive loss $ (299 ) $ (811 ) Other comprehensive income (loss) reclassification adjustments for the three months ended September 30, 2019 and 2018 are as follows: Three Months Ended September 30 2019 2018 Investments: Net holding gain (loss) on investment securities arising during the period, net of tax (expense) benefit of ($35) and $12, respectively $ 119 $ (45 ) Reclassification adjustment for net realized (gain) loss on investment securities, net of tax expense (benefit) of $1 and ($3), respectively (3 ) 9 Total reclassification adjustment on investments 116 (36 ) Non-credit component of other-than-temporary impairments on investments: Non-credit component of other-than-temporary impairments on investments, net of tax expense of ($0) and ($2), respectively (1 ) (2 ) Cash flow hedges: Holding (loss) gain, net of tax expense of ($2) and ($1), respectively (34 ) 2 Other: Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, net of tax expense of ($1) and ($2), respectively 4 7 Foreign currency translation adjustment, net of tax expense of ($0) and ($0), respectively (1 ) — Net gain (loss) recognized in other comprehensive income, net of tax (expense) benefit of ($37) and $4, respectively $ 84 $ (29 ) Other comprehensive income (loss) reclassification adjustments for the nine months ended September 30, 2019 and 2018 are as follows: Nine Months Ended September 30 2019 2018 Investments: Net holding gain (loss) on investment securities arising during the period, net of tax (expense) benefit of ($205) and $109, respectively $ 705 $ (378 ) Reclassification adjustment for net realized (gain) loss on investment securities, net of tax benefit of $(1) and $(7), respectively 6 25 Total reclassification adjustment on investments 711 (353 ) Non-credit component of other-than-temporary impairments on investments: Non-credit component of other-than-temporary impairments on investments, net of tax expense of ($0) and ($2), respectively (2 ) (2 ) Cash flow hedges: Holding (loss) gain, net of tax expense of ($2) and ($9), respectively (31 ) 34 Other: Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, net of tax expense of ($3) and ($7), respectively 10 22 Foreign currency translation adjustment, net of tax expense of ($0) and ($1), respectively (1 ) — Net gain (loss) recognized in other comprehensive income, net of tax (expense) benefit of ($211) and $83, respectively $ 687 $ (299 )

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Earnings Per Share	Earnings per Share The denominator for basic and diluted earnings per share for the three and nine months ended September 30, 2019 and 2018 is as follows: Three Months Ended Nine Months Ended 2019 2018 2019 2018 Denominator for basic earnings per share – weighted-average shares 255.2 259.5 256.3 258.0 Effect of dilutive securities – employee stock options, nonvested restricted stock awards, convertible debentures and equity units 4.8 5.9 4.8 6.3 Denominator for diluted earnings per share 260.0 265.4 261.1 264.3 During the three months ended September 30, 2019 and 2018 , weighted-average shares related to certain stock options of 0.7 and 0.0 , respectively, were excluded from the denominator for diluted earnings per share because the stock options were anti-dilutive. During each of the nine months ended September 30, 2019 and 2018 , weighted-average shares related to certain stock options of 0.6 and 0.4 , respectively, were excluded from the denominator for diluted earnings per share because the stock options were anti-dilutive. During the three and nine months ended September 30, 2019 , we issued approximately 0.0 and 0.5 restricted stock units under our stock incentive plans, 0.2 of which vesting is contingent upon us meeting specified annual earnings targets for the three year period of 2019 through 2021. During the three and nine months ended September 30, 2018 , we issued approximately 0.0 and 0.9 restricted stock units under our stock incentive plans, 0.3

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Segment Information	Segment Information The results of our operations are described through three reportable segments: Commercial & Specialty Business, Government Business and Other, as further described in Note 19, “Segment Information,” to our audited consolidated financial statements as of and for the year ended December 31, 2018 included in our 2018 Annual Report on Form 10-K. Prior to the second quarter of 2019, our Other segment included certain eliminations and corporate expenses not allocated to either of our other reportable segments. Beginning in the second quarter of 2019, our Other segment also includes IngenioRx, our PBM, which began its operations during the second quarter of 2019. In addition, during the second quarter, we reclassified our Diversified Business Group, or DBG, our integrated health services business, from our Government Business segment to the Other segment to reflect changes in how our segments are being managed. Amounts for 2018 have been reclassified to conform to the current year presentation for comparability. Based on the FASB guidance, as of September 30, 2019, IngenioRx and DBG do not collectively meet the quantitative thresholds for an operating segment. Affiliated revenues represent revenues or cost for services provided by IngenioRx and DBG to our subsidiaries, are recorded at cost or management’s estimate of fair market value, and are eliminated in consolidation. For our segment reporting, operating gains (losses) generated from IngenioRx and DBG affiliated activity have been included in our Commercial & Specialty Business and Government Business based upon their utilization of services from IngenioRx and DBG. Financial data by reportable segment for the three and nine months ended September 30, 2019 and 2018 is as follows: Commercial & Specialty Business Government Business Other Eliminations Total Three Months Ended September 30, 2019 Operating revenue - unaffiliated $ 9,284 $ 15,955 $ 1,205 $ — $ 26,444 Operating revenue - affiliated — — 1,303 (1,303 ) — Operating gain (loss) 930 616 (18 ) — 1,528 Three Months Ended September 30, 2018 Operating revenue - unaffiliated $ 8,933 $ 13,979 $ 68 $ — $ 22,980 Operating revenue - affiliated — — 330 (330 ) — Operating gain (loss) 834 456 (41 ) — 1,249 Nine Months Ended September 30, 2019 Operating revenue - unaffiliated $ 28,093 $ 46,419 $ 1,497 $ — $ 76,009 Operating revenue - affiliated — — 2,353 (2,353 ) — Operating gain (loss) 3,511 1,471 (81 ) — 4,901 Nine Months Ended September 30, 2018 Operating revenue - unaffiliated $ 26,939 $ 40,951 $ 147 $ — $ 68,037 Operating revenue - affiliated — — 961 (961 ) — Operating gain (loss) 3,284 1,477 (85 ) — 4,676 The major product revenues for each of the reportable segments for the three and nine months ended September 30, 2019 and 2018 are as follows: Three Months Ended Nine Months Ended 2019 2018 2019 2018 Commercial & Specialty Business Managed care products $ 7,542 $ 7,211 $ 22,806 $ 21,852 Managed care services 1,330 1,332 4,049 3,913 Dental/Vision products and services 325 306 975 914 Other 87 84 263 260 Total Commercial & Specialty Business 9,284 8,933 28,093 26,939 Government Business Managed care products 15,847 13,860 46,111 40,610 Managed care services 108 119 308 341 Total Government Business 15,955 13,979 46,419 40,951 Other Other 2,508 398 3,850 1,108 Eliminations Eliminations (1,303 ) (330 ) (2,353 ) (961 ) Total product revenues $ 26,444 $ 22,980 $ 76,009 $ 68,037 The classification between managed care products and managed care services in the above table primarily distinguishes between the levels of risk assumed. Managed care products represent insurance products where we bear the insurance risk, whereas managed care services represent product offerings where we provide claims adjudication and other administrative services to the customer, but the customer principally bears the insurance risk. A reconciliation of reportable segments’ operating revenue to the amounts of total revenues included in our consolidated statements of income for the three and nine months ended September 30, 2019 and 2018 is as follows: Three Months Ended Nine Months Ended 2019 2018 2019 2018 Reportable segments’ operating revenue $ 26,444 $ 22,980 $ 76,009 $ 68,037 Net investment income 242 250 737 708 Net realized gains on financial instruments 1 27 90 5 Other-than-temporary impairment losses recognized in income (13 ) (6 ) (30 ) (18 ) Total revenues $ 26,674 $ 23,251 $ 76,806 $ 68,732 A reconciliation of reportable segments’ operating gain to income before income tax expense included in our consolidated statements of income for the three and nine months ended September 30, 2019 and 2018 is as follows: Three Months Ended Nine Months Ended 2019 2018 2019 2018 Reportable segments’ operating gain $ 1,528 $ 1,249 $ 4,901 $ 4,676 Net investment income 242 250 737 708 Net realized gains on financial instruments 1 27 90 5 Other-than-temporary impairment losses recognized in income (13 ) (6 ) (30 ) (18 ) Interest expense (185 ) (188 ) (556 ) (564 ) Amortization of other intangible assets (84 ) (91 ) (256 ) (265 ) Gain (loss) on extinguishment of debt — 1 1 (17 ) Income before income tax expense $ 1,489 $ 1,242 $ 4,887 $ 4,525

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	Leases We lease office space and certain computer and related equipment using noncancelable operating leases. Our leases have remaining lease terms of 1 year to 15 years. The information related to our leases is as follows: Balance Sheet Location September 30, 2019 Operating Leases Right-of-use assets Other noncurrent assets $ 577 Lease liabilities, current Other current liabilities 167 Lease liabilities, noncurrent Other noncurrent liabilities 473 Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 Lease Expense Operating lease expense $ 48 $ 138 Short-term lease expense 9 33 Sublease income (4 ) (12 ) Total lease expense $ 53 $ 159 Other information Operating cash paid for amounts included in the measurement of lease liabilities, operating leases $ 43 $ 132 Right-of-use assets obtained in exchange for new lease liabilities, operating leases $ 33 $ 33 Weighted average remaining lease term, operating leases 6 years 6 years Weighted average discount rate, operating leases 3.96 % 3.96 % At September 30, 2019 , future lease payments for noncancellable operating leases with initial or remaining terms of one year or more are as follows: 2019 (excluding the nine months ended September 30, 2019) $ 60 2020 163 2021 133 2022 121 2023 103 Thereafter 79 Total future minimum payments 659 Less imputed interest (19 ) Total lease liabilities $ 640 As of September 30, 2019 , we have additional operating leases for building spaces that have not yet commenced, and some building spaces are being constructed by the lessors and their agents. These leases have terms of up to 12 years and are expected to commence on various dates during 2020 and 2021 when the construction is complete and we take possession of the buildings . The undiscounted lease payments for these leases, which are not included in the tables above, aggregate $147 .

Basis of Presentation and Sig_2

Basis of Presentation and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation: The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP, for interim financial reporting. Accordingly, they do not include all of the information and footnotes required by GAAP for annual financial statements. We have omitted certain footnote disclosures that would substantially duplicate the disclosures in our 2018 Annual Report on Form 10-K, unless the information contained in those disclosures materially changed or is required by GAAP. Certain prior year amounts have been reclassified to conform to the current year presentation or adjusted to conform to the current year rounding convention of reporting financial data in whole millions of dollars, except as otherwise noted. For additional information on prior year reclassifications, see Note 15, “Segment Information.” In the opinion of management, all adjustments, including normal recurring adjustments, necessary for a fair statement of the consolidated financial statements as of and for the three and nine months ended September 30, 2019 and 2018 have been recorded. The results of operations for the three and nine months ended September 30, 2019 are not necessarily indicative of the results that may be expected for the full year ending December 31, 2019 , or any other period. These unaudited consolidated financial statements should be read in conjunction with our audited consolidated financial statements as of and for the year ended December 31, 2018 included in our 2018 Annual Report on Form 10-K.
Foreign Currency	Certain of our subsidiaries operate outside of the United States and have functional currencies other than the U.S. dollar, or USD. We translate the assets and liabilities of those subsidiaries to USD using the exchange rate in effect at the end of the period. We translate the revenues and expenses of those subsidiaries to USD using the average exchange rates in effect during the period. The net effect of these translation adjustments is included in “Foreign currency translation adjustments” in our consolidated statements of comprehensive income.
Cash and Cash Equivalents	Cash and Cash Equivalents: We control a number of bank accounts that are used exclusively to hold customer funds for the administration of customer benefits and have cash and cash equivalents on deposit to meet certain regulatory requirements. These amounts totaled $242 and $222 at September 30, 2019 and December 31, 2018 , respectively, and are included in the cash and cash equivalents line on our consolidated balance sheets.
Leases	Leases: We lease office space and certain computer and related equipment under noncancelable operating leases. We determine whether an arrangement is or contains a lease at its inception. We recognize lease liabilities based on the present value of the minimum lease payments not yet paid by using the lease term, any amounts probable of being owed under any residual value guarantees and discount rate determined at lease commencement. As our leases do not generally provide an implicit rate, we use our incremental secured borrowing rate commensurate with the underlying lease terms to determine the present value of our lease payments. Our leases may include options to extend or terminate a lease when it is reasonably certain that we will exercise that option. We recognize the operating right-of-use, or ROU, assets at an amount equal to the lease liability adjusted for prepaid or accrued rent, the remaining balance of any lease incentives and unamortized initial direct costs. The operating lease liabilities are reported in other current liabilities and other noncurrent liabilities and the related ROU assets are reported in other noncurrent assets on our consolidated balance sheet as of September 30, 2019 . Lease expense for our operating leases is calculated on a straight-line basis over the lease term and is reported in selling, general and administrative expense on our consolidated statements of income. For our office space leases, we account for the lease and non-lease components (such as common area maintenance) as a single lease component. We also do not recognize a lease liability or ROU asset for our office space leases whose lease terms, at commencement, are twelve months or less and that do not include a purchase option or option to extend that we are reasonably certain to exercise.
Revenue Recognition	Revenue Recognition: Premiums for fully-insured contracts are recognized as revenue over the period insurance coverage is provided, and, if applicable, net of amounts recognized for the minimum medical loss ratio rebates or contractual or government-mandated premium stabilization programs. Administrative fees and other revenues include revenue from certain group contracts that provide for the group to be at risk for all, or with supplemental insurance arrangements, a portion of their claims experience. We charge these self-funded groups an administrative fee, which is based on the number of members in a group or the group’s claim experience. Under our self-funded arrangements, revenue is recognized as administrative services are performed, and benefit payments under these programs are excluded from benefit expense. Beginning in the second quarter of 2019, administrative fees and other revenues also include unaffiliated revenue from services performed by IngenioRx. For additional information about our revenues, see Note 2, “Basis of Presentation and Significant Accounting Policies” and Note 19, “Segment Information,” to our audited consolidated financial statements as of and for the year ended December 31, 2018 included in our 2018 Annual Report on Form 10-K. In addition, see Note 15, “Segment Information,” herein for the disaggregation of revenues by segments and products. For our non-fully-insured contracts, we had no material contract assets, contract liabilities or deferred contract costs recorded on our consolidated balance sheet at September 30, 2019 . For the three and nine months ended September 30, 2019 , revenue recognized from performance obligations related to prior periods, such as due to changes in transaction price, was not material. For contracts that have an original expected duration of greater than one year, revenue expected to be recognized in future periods related to unfulfilled contractual performance obligations and contracts with variable consideration related to undelivered performance obligations is not material.
Recently Adopted Accounting Guidance	Recently Adopted Accounting Guidance: In March 2019, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update No. 2019-01, Leases (Topic 842): Codification Improvements . In July 2018, the FASB issued Accounting Standards Update No. 2018-11, Leases (Topic 842): Targeted Improvements and Accounting Standards Update No. 2018-10, Codification Improvements to Topic 842, Leases . These updates provide additional clarification, an optional transition method, a practical expedient and implementation guidance on the previously issued Accounting Standards Update No. 2016-02, Leases (Topic 842) . Collectively, these updates supersede the lease guidance in Accounting Standards Codification, or ASC, Topic 840 and require lessees to recognize for all leases, with the exception of short-term leases, a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis. Concurrently, lessees are required to recognize an ROU asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. We adopted this standard on January 1, 2019 by applying the optional transition method on the adoption date and did not adjust comparative periods. We also elected the package of practical expedients permitted, which, among other things, allowed us to carry forward the lease classification for our existing leases. In preparation for the adoption of this standard and to enable preparation of the required financial information, we implemented a new lease accounting software solution as well as new internal controls. The adoption of this standard impacted our 2019 opening consolidated balance sheet, as we recorded operating lease liabilities of $728 and ROU assets of $637 , which equals the lease liabilities net of accrued rent, lease incentives and the carrying amount of ceased-use liabilities previously recorded on our consolidated balance sheet under the old guidance. We also recognized a cumulative-effect adjustment of $26 to our opening retained earnings for deferred gains on our previous sale-leaseback transactions. The adoption of this standard did not have an impact on our consolidated statements of income or cash flows. In August 2018, the FASB issued Accounting Standards Update No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, or ASU 2018-13. The amendments in ASU 2018-13 eliminate, add, and modify certain disclosure requirements for fair value measurements. The amendments are effective for interim and annual periods beginning after December 15, 2019, with early adoption permitted for either the entirety of ASU 2018-13 or only the provisions that eliminate or modify disclosure requirements. We early adopted the provisions that eliminate and modify disclosure requirements, on a retrospective basis, effective in our 2018 Annual Report on Form 10-K. We will adopt the new disclosure requirements, on a prospective basis, effective for our interim and annual reporting periods beginning after December 15, 2019. In February 2018, the FASB issued Accounting Standards Update No. 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , or ASU 2018-02. On December 22, 2017, the federal government enacted a tax bill, H.R.1, An act to provide for reconciliation pursuant to titles II and V of the concurrent resolution on the budget for fiscal year 2018 , or the Tax Cuts and Jobs Act. The Tax Cuts and Jobs Act contains significant changes to corporate taxation, including, but not limited to, reducing the U.S. federal corporate income tax rate from 35% to 21% and modifying or limiting many business deductions. Current FASB guidance requires adjustments of deferred taxes due to a change in the federal corporate income tax rate to be included in income from operations. As a result, the tax effects of items within accumulated other comprehensive loss did not reflect the appropriate tax rate. The amendments in ASU 2018-02 allowed a reclassification from accumulated other comprehensive loss to retained earnings for stranded tax effects resulting from the change in the federal corporate income tax rate. We adopted the amendments in ASU 2018-02 for our interim and annual reporting periods beginning on January 1, 2018 and reclassified $91 of stranded tax effects from accumulated other comprehensive loss to retained earnings on our consolidated balance sheets. The adoption of ASU 2018-02 did not have any impact on our consolidated results of operations or cash flows. In May 2017, the FASB issued Accounting Standards Update No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting , or ASU 2017-09. This update provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in ASC Topic 718. We adopted ASU 2017-09 on January 1, 2018. The guidance has been and will be applied prospectively to awards modified on or after the adoption date. The adoption of ASU 2017-09 did not have any impact on our consolidated financial position, results of operations or cash flows. In March 2017, the FASB issued Accounting Standards Update No. 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities , or ASU 2017-08. This update changes the amortization period for certain purchased callable debt securities held at a premium by shortening the amortization period for the premium to the earliest call date. Under the old guidance, the premium was generally amortized over the contractual life of the instrument. The amendments are to be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. We adopted ASU 2017-08 on January 1, 2019, and the adoption of this standard did not have a material impact on our beginning retained earnings or on our consolidated financial position, results of operations or cash flows. In March 2017, the FASB issued Accounting Standards Update No. 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost , or ASU 2017-07. This amendment requires entities to disaggregate the service cost component from the other components of the benefit cost and present the service cost component in the same income statement line item as other employee compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. Certain of our defined benefit plans have previously been frozen, resulting in no annual service costs, and the remaining service costs for our non-frozen plan are not material. We adopted ASU 2017-07 on January 1, 2018, and it did not have a material impact on our consolidated results of operations, cash flows or financial position. In December 2016, the FASB issued Accounting Standards Update No. 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers. In May 2016, the FASB issued Accounting Standards Update No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients . In April 2016, the FASB issued Accounting Standards Update No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing . In March 2016, the FASB issued Accounting Standards Update No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net) . These updates provide additional clarification and implementation guidance on the previously issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) . Collectively, these updates require a company to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. These updates supersede almost all existing revenue recognition guidance under GAAP, with certain exceptions, including an exception for our premium revenues, which are recorded on the Premiums line item on our consolidated statements of income and will continue to be accounted for in accordance with the provisions of ASC Topic 944, Financial Services - Insurance . Our administrative service and other contracts that are subject to these Accounting Standards Updates are recorded in the Administrative fees and other revenue line item on our consolidated statements of income and represent approximately 6% of our consolidated total operating revenue. We adopted these standards on January 1, 2018 using the modified retrospective approach. The adoption of these standards did not have a material impact on our beginning retained earnings, or on our consolidated results of operations, cash flows or financial position. In November 2016, the FASB issued Accounting Standards Update No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash, or ASU 2016-18. This update amends ASC Topic 230, Statement of Cash Flows , to add and clarify guidance on the classification and presentation of restricted cash in the statement of cash flows. The guidance requires entities to show the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. We adopted ASU 2016-18 on January 1, 2018 using a retrospective approach. The adoption of ASU 2016-18 did not have a material impact on our consolidated statements of cash flows and did not impact our consolidated results of operations or financial position. In August 2016, the FASB issued Accounting Standards Update No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments, or ASU 2016-15. This update addresses the presentation and classification on the statement of cash flows for eight specific items, with the objective of reducing existing diversity in practice in how certain cash receipts and cash payments are presented and classified. We adopted ASU 2016-15 on January 1, 2018. The adoption of ASU 2016-15 did not have a material impact on our consolidated statements of cash flows, results of operations or financial position. In January 2016, the FASB issued Accounting Standards Update No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities , or ASU 2016-01. The amendments in ASU 2016-01 change the accounting for non-consolidated equity investments that are not accounted for under the equity method of accounting by requiring changes in fair value to be recognized in income. Additionally, ASU 2016-01 simplifies the impairment assessment of equity investments without readily determinable fair values; requires entities to use the exit price when estimating the fair value of financial instruments; and modifies various presentation disclosure requirements for financial instruments. We adopted ASU 2016-01 on January 1, 2018 as a cumulative-effect adjustment and reclassified $320 of unrealized gains on equity investments, net of tax, from accumulated other comprehensive loss to retained earnings on our consolidated balance sheets. Effective January 1, 2018, our results of operations include the changes in fair value of these financial instruments.
Recent Accounting Guidance Not Yet Adopted	Recent Accounting Guidance Not Yet Adopted: In May 2019, the FASB issued Accounting Standards Update No. 2019-05, Financial Instruments - Credit Losses (Topic 326): Targeted Transition Relief, or ASU 2019-05. In April 2019, the FASB issued Accounting Standards Update No. 2019-04, Codification Improvements to Topic 326, Financial Instruments - Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments . In November 2018, the FASB issued Accounting Standards Update No. 2018-19, Codification Improvements to Topic 326, Financial Instruments - Credit Losses . These updates provide an option to irrevocably elect to measure certain individual financial assets at fair value instead of amortized cost and provide additional clarification and implementation guidance on certain aspects of the previously issued Accounting Standards Update No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, or ASU 2016-13, and have the same effective date and transition requirements as ASU 2016-13. ASU 2016-13 introduces a current expected credit loss model for measuring expected credit losses for certain types of financial instruments held at the reporting date based on historical experience, current conditions and reasonable supportable forecasts. ASU 2016-13 replaces the current incurred loss model for measuring expected credit losses, requires expected losses on available-for-sale debt securities to be recognized through an allowance for credit losses rather than as reductions in the amortized cost of the securities and provides for additional disclosure requirements. ASU 2016-13 requires a cumulative-effect adjustment to the statement of financial position to the opening balance of retained earnings at the date of adoption and a prospective transition approach for debt securities for which an other-than-temporary impairment had been recognized before the adoption date. The effect of a prospective transition approach is to maintain the same amortized cost basis before and after the date of adoption. ASU 2016-13 is effective for us on January 1, 2020, with early adoption permitted. We are currently gathering data and evaluating the effects the adoption of ASU 2016-13 will have on our consolidated financial statements. In August 2018, the FASB issued Accounting Standards Update No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract , or ASU 2018-15. The amendments in ASU 2018-15 require implementation costs incurred by customers in cloud computing arrangements to be deferred and recognized over the term of the arrangement, if those costs would be capitalized by the customer in a software licensing arrangement under the internal-use software guidance. The amendments also require an entity to disclose the nature of its hosting arrangements and adhere to certain presentation requirements in its balance sheet, income statement and statement of cash flows. ASU 2018-15 is effective for us on January 1, 2020, with early adoption permitted. The guidance can be applied either prospectively to all implementation costs incurred after the date of adoption or retrospectively. While we are continuing to evaluate the effects the adoption of ASU 2018-15 will have on our consolidated financial position, results of operations and cash flows; we intend to apply the prospective method of adoption. In August 2018, the FASB issued Accounting Standards Update No. 2018-14, Compensation—Retirement Benefits - Defined Benefit Plans—General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans , or ASU 2018-14. The amendments in ASU 2018-14 eliminate, add, and modify certain disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The amendments are effective for our annual reporting periods beginning after December 15, 2020, with early adoption permitted. The guidance is to be applied on a retrospective basis to all periods presented. We are currently evaluating the effects the adoption of ASU 2018-14 will have on our disclosures. In August 2018, the FASB issued Accounting Standards Update No. 2018-12, Financial Services—Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts, or ASU 2018-12. The amendments in ASU 2018-12 make changes to a variety of areas to simplify or improve the existing recognition, measurement, presentation and disclosure requirements for long-duration contracts issued by an insurance entity. The amendments require insurers to annually review the assumptions they make about their policyholders and update the liabilities for future policy benefits if the assumptions change. The amendments also simplify the amortization of deferred contract acquisition costs and add new disclosure requirements about the assumptions insurers use to measure their liabilities and how they may affect future cash flows. The amendments in ASU 2018-12 will be effective for our interim and annual reporting periods beginning after December 15, 2020. The amendments related to the liability for future policy benefits for traditional and limited-payment contracts and deferred acquisition costs are to be applied to contracts in force as of the beginning of the earliest period presented, with an option to apply such amendments retrospectively with a cumulative-effect adjustment to the opening balance of retained earnings as of the earliest period presented. The amendments for market risk benefits are to be applied retrospectively. We are currently evaluating the effects the adoption of ASU 2018-12 will have on our consolidated financial position, results of operations, cash flows, and related disclosures. In January 2017, the FASB issued Accounting Standards Update No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment , or ASU 2017-04. This update removes Step 2 of the goodwill impairment test under current guidance, which requires a hypothetical purchase price allocation. The new guidance requires an impairment charge to be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value. Upon adoption, the guidance is to be applied prospectively. ASU 2017-04 is effective for us on January 1, 2020, with early adoption permitted. The adoption of ASU 2017-04 is not expected to have a material impact on our consolidated financial position, results of operations or cash flows. There were no other new accounting pronouncements that were issued or became effective since the issuance of our 2018 Annual Report on Form 10-K that had, or are expected to have, a material impact on our consolidated financial position, results of operations or cash flows.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2019
Investment [Line Items]
Current and Long-Term Investments, Available-For-Sale	A summary of current and long-term fixed maturity securities, available-for-sale, at September 30, 2019 and December 31, 2018 is as follows: Non-Credit Component of OTTIs Other Comprehensive Loss Cost or Gross Gross Unrealized Losses Estimated Less than 12 Months 12 Months or Greater September 30, 2019 Fixed maturity securities: United States Government securities $ 487 $ 10 $ — $ — $ 497 $ — Government sponsored securities 125 6 — — 131 — States, municipalities and political subdivisions 4,469 275 (1 ) (1 ) 4,742 — Corporate securities 9,040 341 (17 ) (25 ) 9,339 (5 ) Residential mortgage-backed securities 3,914 111 (4 ) (4 ) 4,017 — Commercial mortgage-backed securities 87 3 — — 90 — Other securities 1,645 24 (2 ) (5 ) 1,662 — Total fixed maturity securities $ 19,767 $ 770 $ (24 ) $ (35 ) $ 20,478 $ (5 ) December 31, 2018 Fixed maturity securities: United States Government securities $ 414 $ 3 $ — $ (1 ) $ 416 $ — Government sponsored securities 108 1 — (1 ) 108 — States, municipalities and political subdivisions 4,716 91 (3 ) (19 ) 4,785 — Corporate securities 8,189 33 (170 ) (115 ) 7,937 (3 ) Residential mortgage-backed securities 2,769 31 (3 ) (47 ) 2,750 — Commercial mortgage-backed securities 69 — — (2 ) 67 — Other securities 1,115 14 (8 ) (5 ) 1,116 — Total fixed maturity securities $ 17,380 $ 173 $ (184 ) $ (190 ) $ 17,179 $ (3 )
Aggregate Fair Value and Gross Unrealized Loss of Fixed Maturity Securities in an Unrealized Loss Position	For fixed maturity securities in an unrealized loss position at September 30, 2019 and December 31, 2018 , the following table summarizes the aggregate fair values and gross unrealized losses by length of time those securities have continuously been in an unrealized loss position: Less than 12 Months 12 Months or Greater (Securities are whole amounts) Number of Securities Estimated Fair Value Gross Unrealized Loss Number of Securities Estimated Fair Value Gross Unrealized Loss September 30, 2019 Fixed maturity securities: United States Government securities 8 $ 49 $ — 5 $ 14 $ — Government sponsored securities 6 5 — 3 1 — States, municipalities and political subdivisions 66 108 (1 ) 16 13 (1 ) Corporate securities 455 711 (17 ) 338 509 (25 ) Residential mortgage-backed securities 228 422 (4 ) 215 323 (4 ) Commercial mortgage-backed securities 1 3 — 4 8 — Other securities 190 483 (2 ) 107 332 (5 ) Total fixed maturity securities 954 $ 1,781 $ (24 ) 688 $ 1,200 $ (35 ) December 31, 2018 Fixed maturity securities: United States Government securities 5 $ 47 $ — 25 $ 79 $ (1 ) Government sponsored securities 8 11 — 24 31 (1 ) States, municipalities and political subdivisions 177 295 (3 ) 604 1,032 (19 ) Corporate securities 2,185 4,503 (170 ) 1,220 2,072 (115 ) Residential mortgage-backed securities 259 383 (3 ) 816 1,458 (47 ) Commercial mortgage-backed securities 6 11 — 19 37 (2 ) Other securities 193 599 (8 ) 93 237 (5 ) Total fixed maturity securities 2,833 $ 5,849 $ (184 ) 2,801 $ 4,946 $ (190 )
Amortized Cost and Fair Value of Fixed Maturity Securities, By Contractual Maturity	The amortized cost and fair value of fixed maturity securities at September 30, 2019 , by contractual maturity, are shown below. Expected maturities may differ from contractual maturities because the issuers of the securities may have the right to prepay obligations. Amortized Cost Estimated Fair Value Due in one year or less $ 628 $ 628 Due after one year through five years 5,569 5,701 Due after five years through ten years 5,504 5,731 Due after ten years 4,065 4,311 Mortgage-backed securities 4,001 4,107 Total fixed maturity securities $ 19,767 $ 20,478
Proceeds and Realized Gains and Losses from Investments	Proceeds from sales, maturities, calls or redemptions of fixed maturity securities and the related gross realized gains and gross realized losses for the three and nine months ended September 30, 2019 and 2018 are as follows: Three Months Ended Nine Months Ended 2019 2018 2019 2018 Proceeds $ 2,048 $ 1,532 $ 5,502 $ 6,413 Gross realized gains 26 12 66 73 Gross realized losses (9 ) (16 ) (43 ) (85 )
Investments In Equity Securities	A summary of current and long-term marketable equity securities at September 30, 2019 and December 31, 2018 is as follows: September 30, 2019 December 31, 2018 Equity securities: Exchange traded funds $ 563 $ 2 Fixed maturity mutual funds 631 557 Common equity securities 829 654 Private equity securities 306 313 Total $ 2,329 $ 1,526
Gains (Losses) Related to Equity Securities	The gains and losses related to equity securities for the three and nine months ended September 30, 2019 and 2018 are as follows: Three Months Ended September 30 Nine Months Ended September 30 2019 2018 2019 2018 Net realized (losses) gains recognized on equity securities $ (16 ) $ 27 $ 75 $ (33 ) Less: Net realized gains recognized on equity securities sold during the period (6 ) (11 ) (55 ) (208 ) Unrealized (losses) gains recognized on equity securities still held at September 30 $ (22 ) $ 16 $ 20 $ (241 )
Securities Lending Programs	The remaining contractual maturity of our securities lending agreements at September 30, 2019 is as follows: Overnight and Continuous Securities lending transactions United States Government securities $ 132 Corporate securities 324 Equity securities 9 Total $ 465

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements By Level For Assets Measured At Fair Value On A Recurring Basis	A summary of fair value measurements by level for assets and liabilities measured at fair value on a recurring basis at September 30, 2019 and December 31, 2018 is as follows: Level I Level II Level III Total September 30, 2019 Assets: Cash equivalents $ 1,258 $ — $ — $ 1,258 Fixed maturity securities, available-for-sale: United States Government securities — 497 — 497 Government sponsored securities — 131 — 131 States, municipalities and political subdivisions — 4,742 — 4,742 Corporate securities — 9,028 311 9,339 Residential mortgage-backed securities — 4,014 3 4,017 Commercial mortgage-backed securities — 90 — 90 Other securities — 1,651 11 1,662 Total fixed maturity securities, available-for-sale — 20,153 325 20,478 Equity securities: Exchange traded funds 563 — — 563 Fixed maturity mutual funds — 631 — 631 Common equity securities 796 33 — 829 Private equity securities — — 306 306 Total equity securities 1,359 664 306 2,329 Other invested assets, current 10 — — 10 Securities lending collateral — 465 — 465 Derivatives — 25 — 25 Total assets $ 2,627 $ 21,307 $ 631 $ 24,565 Liabilities: Derivatives $ — $ (1 ) $ — $ (1 ) Total liabilities $ — $ (1 ) $ — $ (1 ) December 31, 2018 Assets: Cash equivalents $ 1,815 $ — $ — $ 1,815 Fixed maturity securities, available-for-sale: United States Government securities — 416 — 416 Government sponsored securities — 108 — 108 States, municipalities and political subdivisions — 4,785 — 4,785 Corporate securities 2 7,648 287 7,937 Residential mortgage-backed securities — 2,744 6 2,750 Commercial mortgage-backed securities — 67 — 67 Other securities — 1,099 17 1,116 Total fixed maturity securities, available-for-sale 2 16,867 310 17,179 Equity securities: Exchange traded funds 2 — — 2 Fixed maturity mutual funds — 557 — 557 Common equity securities 601 53 — 654 Private equity securities — — 313 313 Total equity securities 603 610 313 1,526 Other invested assets, current 21 — — 21 Securities lending collateral 314 290 — 604 Derivatives — 16 — 16 Total assets $ 2,755 $ 17,783 $ 623 $ 21,161 Liabilities: Derivatives $ — $ (17 ) $ — $ (17 ) Total liabilities $ — $ (17 ) $ — $ (17 )
Reconciliation Of The Beginning And Ending Balances Of Assets Measured At Fair Value On A Recurring Basis Using Level III Inputs	A reconciliation of the beginning and ending balances of assets measured at fair value on a recurring basis using Level III inputs for the three months ended September 30, 2019 and 2018 is as follows: Corporate Securities Residential Mortgage- backed Securities Other Securities Equity Securities Total Three Months Ended September 30, 2019 Beginning balance at July 1, 2019 $ 297 $ 3 $ 11 $ 305 $ 616 Total gains (losses): Recognized in net income (3 ) — — (5 ) (8 ) Recognized in accumulated other comprehensive loss 12 — — — 12 Purchases 28 — — 25 53 Sales (9 ) — — (19 ) (28 ) Settlements (18 ) — — — (18 ) Transfers into Level III 4 — — — 4 Transfers out of Level III — — — — — Ending balance at September 30, 2019 $ 311 $ 3 $ 11 $ 306 $ 631 Change in unrealized losses included in net income related to assets still held at September 30, 2019 $ — $ — $ — $ (4 ) $ (4 ) Three Months Ended September 30, 2018 Beginning balance at July 1, 2018 $ 304 $ 4 $ 26 $ 312 $ 646 Total gains (losses): Recognized in net income — — — 4 4 Recognized in accumulated other comprehensive loss (1 ) — — — (1 ) Purchases 32 — 3 5 40 Sales (2 ) — — (3 ) (5 ) Settlements (30 ) — — — (30 ) Transfers into Level III 6 — 1 — 7 Transfers out of Level III (2 ) — (13 ) — (15 ) Ending balance at September 30, 2018 $ 307 $ 4 $ 17 $ 318 $ 646 Change in unrealized gains included in net income related to assets still held at September 30, 2018 $ — $ — $ — $ 9 $ 9 A reconciliation of the beginning and ending balances of assets measured at fair value on a recurring basis using Level III inputs for the nine months ended September 30, 2019 and 2018 is as follows: Corporate Securities Residential Mortgage- backed Securities Other Securities Equity Securities Total Nine Months Ended September 30, 2019 Beginning balance at January 1, 2019 $ 287 $ 6 $ 17 $ 313 $ 623 Total (losses) gains: Recognized in net income (7 ) — — (5 ) (12 ) Recognized in accumulated other comprehensive loss 14 — — — 14 Purchases 91 — 2 46 139 Sales (11 ) — — (48 ) (59 ) Settlements (58 ) (1 ) (2 ) — (61 ) Transfers into Level III 4 — 3 — 7 Transfers out of Level III (9 ) (2 ) (9 ) — (20 ) Ending balance at September 30, 2019 $ 311 $ 3 $ 11 $ 306 $ 631 Change in unrealized losses included in net income related to assets still held at September 30, 2019 $ — $ — $ — $ (4 ) $ (4 ) Nine Months Ended September 30, 2018 Beginning balance at January 1, 2018 $ 229 $ 5 $ 16 $ 287 $ 537 Total (losses) gains: Recognized in net income 1 — — (228 ) (227 ) Recognized in accumulated other comprehensive loss (3 ) — — — (3 ) Purchases 94 — 12 263 369 Sales (17 ) — — (4 ) (21 ) Settlements (60 ) (1 ) (1 ) — (62 ) Transfers into Level III 65 — 5 — 70 Transfers out of Level III (2 ) — (15 ) — (17 ) Ending balance at September 30, 2018 $ 307 $ 4 $ 17 $ 318 $ 646 Change in unrealized gains included in net income related to assets still held at September 30, 2018 $ — $ — $ — $ 27 $ 27
Carrying And Fair Values By Level Of Financial Instruments Not Recorded At Fair Value On Consolidated Balance Sheet	A summary of the estimated fair values by level of each class of financial instrument that is recorded at its carrying value on our consolidated balance sheets at September 30, 2019 and December 31, 2018 is as follows: Carrying Value Estimated Fair Value Level I Level II Level III Total September 30, 2019 Assets: Other invested assets, long-term $ 3,914 $ — $ — $ 3,914 $ 3,914 Liabilities: Debt: Short-term borrowings 710 — 710 — 710 Commercial paper 500 — 500 — 500 Notes 18,841 — 20,198 — 20,198 Convertible debentures 179 — 893 — 893 December 31, 2018 Assets: Other invested assets, long-term $ 3,726 $ — $ — $ 3,726 $ 3,726 Liabilities: Debt: Short-term borrowings 1,145 — 1,145 — 1,145 Commercial paper 697 — 697 — 697 Notes 17,178 — 17,145 — 17,145 Convertible debentures 191 — 1,030 — 1,030

Retirement Benefits (Tables)

Retirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2019
Defined Benefit Plan [Abstract]
Components of Net Periodic (Benefit Credit) Benefit Cost	The components of net periodic benefit credit included in our consolidated statements of income for the three months ended September 30, 2019 and 2018 are as follows: Pension Benefits Other Benefits Three Months Ended Three Months Ended 2019 2018 2019 2018 Service cost $ — $ 2 $ 1 $ — Interest cost 15 14 3 4 Expected return on assets (35 ) (37 ) (6 ) (6 ) Recognized actuarial loss 5 6 1 1 Settlement loss 4 6 — — Amortization of prior service credit — — (3 ) (3 ) Net periodic benefit credit $ (11 ) $ (9 ) $ (4 ) $ (4 ) The components of net periodic benefit credit included in our consolidated statements of income for the nine months ended September 30, 2019 and 2018 are as follows: Pension Benefits Other Benefits Nine Months Ended Nine Months Ended 2019 2018 2019 2018 Service cost $ — $ 6 $ 1 $ 1 Interest cost 47 41 11 11 Expected return on assets (104 ) (110 ) (17 ) (18 ) Recognized actuarial loss 13 18 2 3 Settlement loss 8 19 — — Amortization of prior service credit — — (9 ) (9 ) Net periodic benefit credit $ (36 ) $ (26 ) $ (12 ) $ (12 )

Medical Claims Payable (Tables)

Medical Claims Payable (Tables)	9 Months Ended
	Sep. 30, 2019
Liability for Claims and Claims Adjustment Expense [Abstract]
Reconciliation Of The Beginning And Ending Balances For Medical Claims Payable	A reconciliation of the beginning and ending balances for medical claims payable, by segment (see Note 15, “Segment Information”), for the nine months ended September 30, 2019 is as follows: Commercial & Specialty Business Government Business Total Gross medical claims payable, beginning of period $ 2,586 $ 4,680 $ 7,266 Ceded medical claims payable, beginning of period (10 ) (24 ) (34 ) Net medical claims payable, beginning of period 2,576 4,656 7,232 Net incurred medical claims: Current period 18,986 39,171 58,157 Prior periods redundancies (162 ) (275 ) (437 ) Total net incurred medical claims 18,824 38,896 57,720 Net payments attributable to: Current period medical claims 16,277 33,474 49,751 Prior periods medical claims 2,213 4,253 6,466 Total net payments 18,490 37,727 56,217 Net medical claims payable, end of period 2,910 5,825 8,735 Ceded medical claims payable, end of period 8 27 35 Gross medical claims payable, end of period $ 2,918 $ 5,852 $ 8,770 At September 30, 2019 , the total of net incurred but not reported liabilities plus expected development on reported claims for the Commercial & Specialty Business was $30 , $171 and $2,709 for the claim years 2017 and prior, 2018 and 2019, respectively. At September 30, 2019 , the total of net incurred but not reported liabilities plus expected development on reported claims for the Government Business was $23 , $105 and $5,697 for the claim years 2017 and prior, 2018 and 2019, respectively. A reconciliation of the beginning and ending balances for medical claims payable, by segment (see Note 15, “Segment Information”), for the nine months ended September 30, 2018 is as follows: Commercial & Specialty Business Government Business Total Gross medical claims payable, beginning of period $ 3,383 $ 4,431 $ 7,814 Ceded medical claims payable, beginning of period (78 ) (27 ) (105 ) Net medical claims payable, beginning of period 3,305 4,404 7,709 Business combinations and purchase adjustments — 199 199 Net incurred medical claims: Current period 17,732 33,664 51,396 Prior periods redundancies (424 ) (434 ) (858 ) Total net incurred medical claims 17,308 33,230 50,538 Net payments attributable to: Current period medical claims 15,275 29,236 44,511 Prior periods medical claims 2,671 3,833 6,504 Total net payments 17,946 33,069 51,015 Net medical claims payable, end of period 2,667 4,764 7,431 Ceded medical claims payable, end of period 10 27 37 Gross medical claims payable, end of period $ 2,677 $ 4,791 $ 7,468
Reconciliation of Net Incurred Medical Claims to Benefit Expense	The reconciliation of net incurred medical claims to benefit expense included in our consolidated statements of income for periods in 2019 are as follows: Three Months Ended Nine Months Ended March 31, 2019 June 30, 2019 September 30, 2019 Net incurred medical claims: Commercial & Specialty Business $ 5,856 $ 6,422 $ 6,546 $ 18,824 Government Business 12,483 13,062 13,351 38,896 Total net incurred medical claims 18,339 19,484 19,897 57,720 Quality improvement and other claims expense 943 884 856 2,683 Benefit expense $ 19,282 $ 20,368 $ 20,753 $ 60,403 Net incurred medical claims for the three months ended March 31, 2019 and June 30, 2019 in the table above include a reclassification between the Commercial and Specialty Business and Government Business segments to adjust certain intercompany eliminations. This reclassification did not impact any other amounts presented in the consolidated financial statements. The reconciliation of net incurred medical claims to benefit expense included in our consolidated statements of income for periods in 2018 are as follows: Three Months Ended Nine Months Ended March 31, 2018 June 30, 2018 September 30, 2018 Net incurred medical claims: Commercial & Specialty Business $ 5,410 $ 5,884 $ 6,014 $ 17,308 Government Business 10,794 11,039 11,397 33,230 Total net incurred medical claims 16,204 16,923 17,411 50,538 Quality improvement and other claims expense 842 805 774 2,421 Benefit expense $ 17,046 $ 17,728 $ 18,185 $ 52,959
Reconciliation of Short Duration Medical Claims Payable to the Consolidated Medical Claims Payable	The reconciliation of the medical claims payable reflected in the tables above to the consolidated ending balance for medical claims payable included in the consolidated balance sheet, as of September 30, 2019 , is as follows: Commercial & Specialty Business Government Business Total Net medical claims payable, end of period $ 2,910 $ 5,825 $ 8,735 Ceded medical claims payable, end of period 8 27 35 Insurance lines other than short duration — 207 207 Gross medical claims payable, end of period $ 2,918 $ 6,059 $ 8,977

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Convertible Debenture Terms	The following table summarizes at September 30, 2019 the related balances, conversion rate and conversion price of the Debentures: Outstanding principal amount $ 267 Unamortized debt discount $ 85 Net debt carrying amount $ 179 Equity component carrying amount $ 97 Conversion rate (shares of common stock per $1,000 of principal amount) 13.9250 Effective conversion price (per $1,000 of principal amount) $ 71.8129

Capital Stock (Tables)

Capital Stock (Tables)	9 Months Ended
	Sep. 30, 2019
Capital [Abstract]
Summary of Cash Dividend Activity	A summary of the cash dividend activity for the nine months ended September 30, 2019 and 2018 is as follows: Declaration Date Record Date Payment Date Cash Dividend per Share Total Nine Months Ended September 30, 2019 January 29, 2019 March 18, 2019 March 29, 2019 $0.80 $ 206 April 23, 2019 June 10, 2019 June 25, 2019 $0.80 $ 206 July 23, 2019 September 10, 2019 September 25, 2019 $0.80 $ 204 Nine Months Ended September 30, 2018 January 30, 2018 March 9, 2018 March 23, 2018 $0.75 $ 192 April 24, 2018 June 8, 2018 June 25, 2018 $0.75 $ 196 July 24, 2018 September 10, 2018 September 25, 2018 $0.75 $ 195
Summary of Share Repurchases	A summary of common stock repurchases from October 1, 2019 through October 16, 2019 (subsequent to September 30, 2019 ) and for the nine months ended September 30, 2019 and 2018 is as follows: October 1, 2019 Nine Months Ended September 30 2019 2018 Shares repurchased 0.4 5.2 5.0 Average price per share $ 238.71 $ 270.42 $ 240.15 Aggregate cost $ 104 $ 1,396 $ 1,192 Authorization remaining at the end of the period $ 3,994 $ 4,098 $ 5,986
Summary of Stock Option Activity	A summary of stock option activity for the nine months ended September 30, 2019 is as follows: Number of Shares Weighted- Average Option Price per Share Weighted- Average Remaining Contractual Life (Years) Aggregate Intrinsic Value Outstanding at January 1, 2019 3.7 $ 149.65 Granted 0.7 306.74 Exercised (0.9 ) 127.92 Forfeited or expired (0.1 ) 238.81 Outstanding at September 30, 2019 3.4 185.47 6.28 $ 233 Exercisable at September 30, 2019 2.2 142.26 5.02 $ 220
Summary of Nonvested Restricted Stock Activity Including Restricted Stock Units	A summary of the nonvested restricted stock activity, including restricted stock units, for the nine months ended September 30, 2019 is as follows: Restricted Stock Shares and Units Weighted- Average Grant Date Fair Value per Share Nonvested at January 1, 2019 1.7 $ 183.32 Granted 0.5 306.13 Vested (0.8 ) 152.97 Forfeited — 243.77 Nonvested at September 30, 2019 1.4 240.92
Summary of Weighted-Average Assumptions Used to Estimate the Fair Value of Options Granted During the Periods	The following weighted-average assumptions were used to estimate the fair values of options granted during the nine months ended September 30, 2019 and 2018 : Nine Months Ended September 30 2019 2018 Risk-free interest rate 2.69 % 2.90 % Volatility factor 25.00 % 30.00 % Quarterly dividend yield 0.260 % 0.323 % Weighted-average expected life (years) 4.40 3.70
Schedule of Weighted-Average Fair Values Determined for the Periods	The following weighted-average fair values per option or share were determined for the nine months ended September 30, 2019 and 2018 : Nine Months Ended September 30 2019 2018 Options granted during the period $ 68.69 $ 55.44 Restricted stock awards granted during the period 306.13 233.27

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2019
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Components Of Accumulated Other Comprehensive Loss	A reconciliation of the components of accumulated other comprehensive loss at September 30, 2019 and 2018 is as follows: September 30 2019 2018 Investments, excluding non-credit component of other-than-temporary impairments: Gross unrealized gains $ 770 $ 170 Gross unrealized losses (54 ) (289 ) Net pre-tax unrealized gains (losses) 716 (119 ) Deferred tax (liability) asset (164 ) 24 Net unrealized gains (losses) on investments 552 (95 ) Non-credit components of other-than-temporary impairments on investments: Unrealized losses (5 ) (2 ) Deferred tax asset 1 — Net unrealized non-credit component of other-than-temporary impairments on investments (4 ) (2 ) Cash flow hedges: Gross unrealized losses (340 ) (315 ) Deferred tax asset 63 66 Net unrealized losses on cash flow hedges (277 ) (249 ) Defined benefit pension plans: Deferred net actuarial loss (730 ) (587 ) Deferred prior service credits (1 ) (1 ) Deferred tax asset 188 153 Net unrecognized periodic benefit costs for defined benefit pension plans (543 ) (435 ) Postretirement benefit plans: Deferred net actuarial loss (57 ) (75 ) Deferred prior service costs 25 37 Deferred tax asset 8 10 Net unrecognized periodic benefit costs for postretirement benefit plans (24 ) (28 ) Foreign currency translation adjustments: Gross unrealized losses (4 ) (2 ) Deferred tax asset 1 — Net unrealized losses on foreign currency translation adjustments (3 ) (2 ) Accumulated other comprehensive loss $ (299 ) $ (811 )
Other Comprehensive Income (Loss) Reclassification Adjustments	Other comprehensive income (loss) reclassification adjustments for the three months ended September 30, 2019 and 2018 are as follows: Three Months Ended September 30 2019 2018 Investments: Net holding gain (loss) on investment securities arising during the period, net of tax (expense) benefit of ($35) and $12, respectively $ 119 $ (45 ) Reclassification adjustment for net realized (gain) loss on investment securities, net of tax expense (benefit) of $1 and ($3), respectively (3 ) 9 Total reclassification adjustment on investments 116 (36 ) Non-credit component of other-than-temporary impairments on investments: Non-credit component of other-than-temporary impairments on investments, net of tax expense of ($0) and ($2), respectively (1 ) (2 ) Cash flow hedges: Holding (loss) gain, net of tax expense of ($2) and ($1), respectively (34 ) 2 Other: Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, net of tax expense of ($1) and ($2), respectively 4 7 Foreign currency translation adjustment, net of tax expense of ($0) and ($0), respectively (1 ) — Net gain (loss) recognized in other comprehensive income, net of tax (expense) benefit of ($37) and $4, respectively $ 84 $ (29 ) Other comprehensive income (loss) reclassification adjustments for the nine months ended September 30, 2019 and 2018 are as follows: Nine Months Ended September 30 2019 2018 Investments: Net holding gain (loss) on investment securities arising during the period, net of tax (expense) benefit of ($205) and $109, respectively $ 705 $ (378 ) Reclassification adjustment for net realized (gain) loss on investment securities, net of tax benefit of $(1) and $(7), respectively 6 25 Total reclassification adjustment on investments 711 (353 ) Non-credit component of other-than-temporary impairments on investments: Non-credit component of other-than-temporary impairments on investments, net of tax expense of ($0) and ($2), respectively (2 ) (2 ) Cash flow hedges: Holding (loss) gain, net of tax expense of ($2) and ($9), respectively (31 ) 34 Other: Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, net of tax expense of ($3) and ($7), respectively 10 22 Foreign currency translation adjustment, net of tax expense of ($0) and ($1), respectively (1 ) — Net gain (loss) recognized in other comprehensive income, net of tax (expense) benefit of ($211) and $83, respectively $ 687 $ (299 )

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Denominator for Basic and Diluted Earnings Per Share	The denominator for basic and diluted earnings per share for the three and nine months ended September 30, 2019 and 2018 is as follows: Three Months Ended Nine Months Ended 2019 2018 2019 2018 Denominator for basic earnings per share – weighted-average shares 255.2 259.5 256.3 258.0 Effect of dilutive securities – employee stock options, nonvested restricted stock awards, convertible debentures and equity units 4.8 5.9 4.8 6.3 Denominator for diluted earnings per share 260.0 265.4 261.1 264.3

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Financial Data By Reportable Segment	Financial data by reportable segment for the three and nine months ended September 30, 2019 and 2018 is as follows: Commercial & Specialty Business Government Business Other Eliminations Total Three Months Ended September 30, 2019 Operating revenue - unaffiliated $ 9,284 $ 15,955 $ 1,205 $ — $ 26,444 Operating revenue - affiliated — — 1,303 (1,303 ) — Operating gain (loss) 930 616 (18 ) — 1,528 Three Months Ended September 30, 2018 Operating revenue - unaffiliated $ 8,933 $ 13,979 $ 68 $ — $ 22,980 Operating revenue - affiliated — — 330 (330 ) — Operating gain (loss) 834 456 (41 ) — 1,249 Nine Months Ended September 30, 2019 Operating revenue - unaffiliated $ 28,093 $ 46,419 $ 1,497 $ — $ 76,009 Operating revenue - affiliated — — 2,353 (2,353 ) — Operating gain (loss) 3,511 1,471 (81 ) — 4,901 Nine Months Ended September 30, 2018 Operating revenue - unaffiliated $ 26,939 $ 40,951 $ 147 $ — $ 68,037 Operating revenue - affiliated — — 961 (961 ) — Operating gain (loss) 3,284 1,477 (85 ) — 4,676
Major Product Revenue by Segment	The major product revenues for each of the reportable segments for the three and nine months ended September 30, 2019 and 2018 are as follows: Three Months Ended Nine Months Ended 2019 2018 2019 2018 Commercial & Specialty Business Managed care products $ 7,542 $ 7,211 $ 22,806 $ 21,852 Managed care services 1,330 1,332 4,049 3,913 Dental/Vision products and services 325 306 975 914 Other 87 84 263 260 Total Commercial & Specialty Business 9,284 8,933 28,093 26,939 Government Business Managed care products 15,847 13,860 46,111 40,610 Managed care services 108 119 308 341 Total Government Business 15,955 13,979 46,419 40,951 Other Other 2,508 398 3,850 1,108 Eliminations Eliminations (1,303 ) (330 ) (2,353 ) (961 ) Total product revenues $ 26,444 $ 22,980 $ 76,009 $ 68,037
Reconciliation Of Reportable Segments Operating Revenues To Total Revenues Reported In The Consolidated Statements Of Income	A reconciliation of reportable segments’ operating revenue to the amounts of total revenues included in our consolidated statements of income for the three and nine months ended September 30, 2019 and 2018 is as follows: Three Months Ended Nine Months Ended 2019 2018 2019 2018 Reportable segments’ operating revenue $ 26,444 $ 22,980 $ 76,009 $ 68,037 Net investment income 242 250 737 708 Net realized gains on financial instruments 1 27 90 5 Other-than-temporary impairment losses recognized in income (13 ) (6 ) (30 ) (18 ) Total revenues $ 26,674 $ 23,251 $ 76,806 $ 68,732
Reconciliation Of Reportable Segments Operating Gain To Income Before Income Tax Expense Included In The Consolidated Statements Of Income	A reconciliation of reportable segments’ operating gain to income before income tax expense included in our consolidated statements of income for the three and nine months ended September 30, 2019 and 2018 is as follows: Three Months Ended Nine Months Ended 2019 2018 2019 2018 Reportable segments’ operating gain $ 1,528 $ 1,249 $ 4,901 $ 4,676 Net investment income 242 250 737 708 Net realized gains on financial instruments 1 27 90 5 Other-than-temporary impairment losses recognized in income (13 ) (6 ) (30 ) (18 ) Interest expense (185 ) (188 ) (556 ) (564 ) Amortization of other intangible assets (84 ) (91 ) (256 ) (265 ) Gain (loss) on extinguishment of debt — 1 1 (17 ) Income before income tax expense $ 1,489 $ 1,242 $ 4,887 $ 4,525

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Lessee, Operating Lease, Disclosure [Table Text Block]	The information related to our leases is as follows: Balance Sheet Location September 30, 2019 Operating Leases Right-of-use assets Other noncurrent assets $ 577 Lease liabilities, current Other current liabilities 167 Lease liabilities, noncurrent Other noncurrent liabilities 473 Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 Lease Expense Operating lease expense $ 48 $ 138 Short-term lease expense 9 33 Sublease income (4 ) (12 ) Total lease expense $ 53 $ 159 Other information Operating cash paid for amounts included in the measurement of lease liabilities, operating leases $ 43 $ 132 Right-of-use assets obtained in exchange for new lease liabilities, operating leases $ 33 $ 33 Weighted average remaining lease term, operating leases 6 years 6 years Weighted average discount rate, operating leases 3.96 % 3.96 %
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	At September 30, 2019 , future lease payments for noncancellable operating leases with initial or remaining terms of one year or more are as follows: 2019 (excluding the nine months ended September 30, 2019) $ 60 2020 163 2021 133 2022 121 2023 103 Thereafter 79 Total future minimum payments 659 Less imputed interest (19 ) Total lease liabilities $ 640

Organization (Details)

Organization (Details) medical_member in Millions	Sep. 30, 2019medical_membercountystates
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of Medical Members | medical_member	41
Number of counties in the Kansas City area the Company does not serve | county	30
Number of states in which the Company is licensed to conduct insurance operations | states	50

Basis of Presentation and Signf

Basis of Presentation and Signficant Accounting Policies Basis of Presentation and Significant Acconting Policies (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2018	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease Liabilities		$ 640
Cumulative effect of new accounting principle in period of adoption				$ 26
Customer funds and cash and cash equivalents on deposit for regulatory requirements		$ 242		$ 222
Approximate percentage of revenues subject to new revenue guidance under ASC 606		6.00%
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset			$ 637
Operating Lease Liabilities			728
Cumulative effect of new accounting principle in period of adoption			$ 26
Accounting Standards Update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of ASU 2018-02	$ 91
Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle in period of adoption					$ 320

Business Acquisitions Business

Business Acquisitions Business Acquisition (Assets Liabilities Acquired) (Details) medical_member in Millions, individual_member in Millions, $ in Millions	Sep. 30, 2019USD ($)medical_memberindividual_memberstates	Dec. 31, 2018USD ($)
Business Acquisition [Line Items]
Number Of Medical Members | medical_member	41
Goodwill	$ 20,500	$ 20,504
Number of States in which Company Operates | states	50
America’s 1st Choice [Member] | Government Business Segment [Member]
Business Acquisition [Line Items]
Goodwill	$ 1,029
Business Acquisition, Goodwill, Expected tax deductible amount	$ 333
Beacon Health Options [Member]
Business Acquisition [Line Items]
Number Of Medical Members | individual_member	40
Number of States in which Company Operates | states	50

Investments (Current And Long-T

Investments (Current And Long-Term Fixed Maturity Securities, Available-For-Sale) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Investments [Line Items]
Gross Unrealized Gains	$ 770		$ 170
Fixed Maturities [Member]
Investments [Line Items]
Cost or Amortized Cost	19,767	$ 17,380
Gross Unrealized Gains	770	173
Gross Unrealized Losses, Less than 12 Months	(24)	(184)
Gross Unrealized Losses, 12 Months or Greater	(35)	(190)
Available-for-sale Securities	20,478	17,179
Non-Credit Component of Other-Than-Temporary Impairments Recognized in Accumulated Other Comprehensive Income	(5)	(3)
Fixed Maturities [Member] | United States Government Securities [Member]
Investments [Line Items]
Cost or Amortized Cost	487	414
Gross Unrealized Gains	10	3
Gross Unrealized Losses, Less than 12 Months	0	0
Gross Unrealized Losses, 12 Months or Greater	0	(1)
Available-for-sale Securities	497	416
Non-Credit Component of Other-Than-Temporary Impairments Recognized in Accumulated Other Comprehensive Income	0	0
Fixed Maturities [Member] | Government Sponsored Securities [Member]
Investments [Line Items]
Cost or Amortized Cost	125	108
Gross Unrealized Gains	6	1
Gross Unrealized Losses, Less than 12 Months	0	0
Gross Unrealized Losses, 12 Months or Greater	0	(1)
Available-for-sale Securities	131	108
Non-Credit Component of Other-Than-Temporary Impairments Recognized in Accumulated Other Comprehensive Income	0	0
Fixed Maturities [Member] | States, Municipalities And Political Subdivisions, Tax-Exempt [Member]
Investments [Line Items]
Cost or Amortized Cost	4,469	4,716
Gross Unrealized Gains	275	91
Gross Unrealized Losses, Less than 12 Months	(1)	(3)
Gross Unrealized Losses, 12 Months or Greater	(1)	(19)
Available-for-sale Securities	4,742	4,785
Non-Credit Component of Other-Than-Temporary Impairments Recognized in Accumulated Other Comprehensive Income	0	0
Fixed Maturities [Member] | Corporate Securities [Member]
Investments [Line Items]
Cost or Amortized Cost	9,040	8,189
Gross Unrealized Gains	341	33
Gross Unrealized Losses, Less than 12 Months	(17)	(170)
Gross Unrealized Losses, 12 Months or Greater	(25)	(115)
Available-for-sale Securities	9,339	7,937
Non-Credit Component of Other-Than-Temporary Impairments Recognized in Accumulated Other Comprehensive Income	(5)	(3)
Fixed Maturities [Member] | Residential Mortgage-Backed Securities [Member]
Investments [Line Items]
Cost or Amortized Cost	3,914	2,769
Gross Unrealized Gains	111	31
Gross Unrealized Losses, Less than 12 Months	(4)	(3)
Gross Unrealized Losses, 12 Months or Greater	(4)	(47)
Available-for-sale Securities	4,017	2,750
Non-Credit Component of Other-Than-Temporary Impairments Recognized in Accumulated Other Comprehensive Income	0	0
Fixed Maturities [Member] | Commercial Mortgage-Backed Securities [Member]
Investments [Line Items]
Cost or Amortized Cost	87	69
Gross Unrealized Gains	3	0
Gross Unrealized Losses, Less than 12 Months	0	0
Gross Unrealized Losses, 12 Months or Greater	0	(2)
Available-for-sale Securities	90	67
Non-Credit Component of Other-Than-Temporary Impairments Recognized in Accumulated Other Comprehensive Income	0	0
Fixed Maturities [Member] | Other Securities [Member]
Investments [Line Items]
Cost or Amortized Cost	1,645	1,115
Gross Unrealized Gains	24	14
Gross Unrealized Losses, Less than 12 Months	(2)	(8)
Gross Unrealized Losses, 12 Months or Greater	(5)	(5)
Available-for-sale Securities	1,662	1,116
Non-Credit Component of Other-Than-Temporary Impairments Recognized in Accumulated Other Comprehensive Income	$ 0	$ 0

Investments (Aggregate Fair Val

Investments (Aggregate Fair Value And Gross Unrealized Loss Of Fixed Maturity Securities In An Unrealized Loss Position) (Details) - Fixed Maturities [Member] $ in Millions	Sep. 30, 2019USD ($)securities	Dec. 31, 2018USD ($)securities
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	954	2,833
Estimated fair value, less than 12 months	$ 1,781	$ 5,849
Gross unrealized loss, less than 12 months	$ (24)	$ (184)
Number of securities, 12 months or greater | securities	688	2,801
Estimated fair value, 12 months or greater	$ 1,200	$ 4,946
Gross unrealized loss, 12 months or greater	$ (35)	$ (190)
United States Government Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	8	5
Estimated fair value, less than 12 months	$ 49	$ 47
Gross unrealized loss, less than 12 months	$ 0	$ 0
Number of securities, 12 months or greater | securities	5	25
Estimated fair value, 12 months or greater	$ 14	$ 79
Gross unrealized loss, 12 months or greater	$ 0	$ (1)
Government Sponsored Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	6	8
Estimated fair value, less than 12 months	$ 5	$ 11
Gross unrealized loss, less than 12 months	$ 0	$ 0
Number of securities, 12 months or greater | securities	3	24
Estimated fair value, 12 months or greater	$ 1	$ 31
Gross unrealized loss, 12 months or greater	$ 0	$ (1)
States, Municipalities And Political Subdivisions, Tax-Exempt [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	66	177
Estimated fair value, less than 12 months	$ 108	$ 295
Gross unrealized loss, less than 12 months	$ (1)	$ (3)
Number of securities, 12 months or greater | securities	16	604
Estimated fair value, 12 months or greater	$ 13	$ 1,032
Gross unrealized loss, 12 months or greater	$ (1)	$ (19)
Corporate Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	455	2,185
Estimated fair value, less than 12 months	$ 711	$ 4,503
Gross unrealized loss, less than 12 months	$ (17)	$ (170)
Number of securities, 12 months or greater | securities	338	1,220
Estimated fair value, 12 months or greater	$ 509	$ 2,072
Gross unrealized loss, 12 months or greater	$ (25)	$ (115)
Residential Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	228	259
Estimated fair value, less than 12 months	$ 422	$ 383
Gross unrealized loss, less than 12 months	$ (4)	$ (3)
Number of securities, 12 months or greater | securities	215	816
Estimated fair value, 12 months or greater	$ 323	$ 1,458
Gross unrealized loss, 12 months or greater	$ (4)	$ (47)
Commercial Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	1	6
Estimated fair value, less than 12 months	$ 3	$ 11
Gross unrealized loss, less than 12 months	$ 0	$ 0
Number of securities, 12 months or greater | securities	4	19
Estimated fair value, 12 months or greater	$ 8	$ 37
Gross unrealized loss, 12 months or greater	$ 0	$ (2)
Other Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	190	193
Estimated fair value, less than 12 months	$ 483	$ 599
Gross unrealized loss, less than 12 months	$ (2)	$ (8)
Number of securities, 12 months or greater | securities	107	93
Estimated fair value, 12 months or greater	$ 332	$ 237
Gross unrealized loss, 12 months or greater	$ (5)	$ (5)

Investments (Amortized Cost And

Investments (Amortized Cost And Fair Value Of Fixed Maturity Securities, By Contractual Maturity) (Details) - Fixed Maturities [Member] - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Schedule of Investments [Line Items]
Due in one year or less, Amortized Cost	$ 628
Due after one year through five years, Amortized Cost	5,569
Due after five years through ten years, Amortized Cost	5,504
Due after ten years, Amortized Cost	4,065
Mortgage-backed securities, Amortized Cost	4,001
Available-for-sale securities, Amortized Cost	19,767	$ 17,380
Due in one year or less, Estimated Fair Value	628
Due after one year through five years, Estimated Fair Value	5,701
Due after five years through ten years, Estimated Fair Value	5,731
Due after ten years, Estimated Fair Value	4,311
Mortgage-backed securities, Estimated Fair Value	4,107
Available-for-sale securities, Estimated Fair Value	$ 20,478	$ 17,179

Investments (Proceeds and Reali

Investments (Proceeds and Realized Gains Losses From Fixed Maturity Securities) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Debt Securities, Available-for-sale [Line Items]
Proceeds	$ 2,048	$ 1,532	$ 5,502	$ 6,413
Gross realized gains	26	12	66	73
Gross realized losses	$ (9)	$ (16)	$ (43)	$ (85)

Investments (Current and Long_2

Investments (Current and Long-term Equity Securities) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Investment [Line Items]
Equity Securities	$ 2,329	$ 1,526
Exchange Traded Funds [Member]
Investment [Line Items]
Equity Securities	563	2
Fixed Maturity Mutual Funds [Member]
Investment [Line Items]
Equity Securities	631	557
Common Equity Securities [Member]
Investment [Line Items]
Equity Securities	829	654
Private Equity Securities [Member]
Investment [Line Items]
Equity Securities	$ 306	$ 313

Investments (Gains and Losses R

Investments (Gains and Losses Recognized on Equity Securities) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Schedule of losses and gains related to equity securities [Line Items]
Net realized (losses) gains on equity securities	$ 1	$ 27	$ 90	$ 5
Equity Securities [Member]
Schedule of losses and gains related to equity securities [Line Items]
Net realized (losses) gains on equity securities	(16)	27	75	(33)
Less: Net realized gains recognized on sale of equity securities during the period	(6)	(11)	(55)	(208)
Unrealized gains (losses) recognized on equity securities still held	$ (22)	$ 16	$ 20	$ (241)

Investments (Securities Lending

Investments (Securities Lending Programs) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral received for securities loaned, at carrying value	$ 465	$ 604
Overnight and Continuous [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral received for securities loaned, at carrying value	465
Overnight and Continuous [Member] | United States Government Securities [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral received for securities loaned, at carrying value	132
Overnight and Continuous [Member] | Corporate Securities [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral received for securities loaned, at carrying value	324
Overnight and Continuous [Member] | Equity Securities [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral received for securities loaned, at carrying value	$ 9

Investments (Narrative) (Detail

Investments (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Schedule of Investments [Line Items]
Fair value of collateral received at time of securities lending transactions	$ 465	$ 604
Securities Lending Transactions Ratio of Fair Value of Collateral Held To Securities On Loan	103.00%	102.00%
Securities lending transactions, initial collateral percentage value	102.00%

Derivative Financial Instrume_2

Derivative Financial Instruments (Financial Statement Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Unrecognized loss for all outstanding and terminated cash flow hedges included in accumulated other comprehensive income	$ (277)		$ (249)
Cash Flow Hedging [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Unrecognized loss for all outstanding and terminated cash flow hedges included in accumulated other comprehensive income	$ (277)	$ (246)

Fair Value (Fair Value Measurem

Fair Value (Fair Value Measurements By Level For Assets Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 1,258	$ 1,815
Equity Securities	2,329	1,526
Other invested assets, current	10	21
Securities lending collateral	465	604
Total assets	24,565	21,161
Total liabilities	(1)	(17)
Exchange Traded Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	563	2
Fixed Maturity Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	631	557
Common Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	829	654
Private Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	306	313
Fixed Maturities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	20,478	17,179
Fixed Maturities [Member] | United States Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	497	416
Fixed Maturities [Member] | Government Sponsored Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	131	108
Fixed Maturities [Member] | States, Municipalities And Political Subdivisions, Tax-Exempt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	4,742	4,785
Fixed Maturities [Member] | Corporate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	9,339	7,937
Fixed Maturities [Member] | Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	4,017	2,750
Fixed Maturities [Member] | Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	90	67
Fixed Maturities [Member] | Other Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	1,662	1,116
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	2,329	1,526
Equity Securities [Member] | Exchange Traded Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	563	2
Equity Securities [Member] | Fixed Maturity Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	631	557
Equity Securities [Member] | Common Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	829	654
Equity Securities [Member] | Private Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	306	313
Other Invested Assets, Current [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, current	10	21
Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	25	16
Derivative liabilities	(1)	(17)
Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,258	1,815
Securities lending collateral	0	314
Total assets	2,627	2,755
Total liabilities	0	0
Level I [Member] | Fixed Maturities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	2
Level I [Member] | Fixed Maturities [Member] | United States Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Level I [Member] | Fixed Maturities [Member] | Government Sponsored Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Level I [Member] | Fixed Maturities [Member] | States, Municipalities And Political Subdivisions, Tax-Exempt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Level I [Member] | Fixed Maturities [Member] | Corporate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	2
Level I [Member] | Fixed Maturities [Member] | Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Level I [Member] | Fixed Maturities [Member] | Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Level I [Member] | Fixed Maturities [Member] | Other Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Level I [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	1,359	603
Level I [Member] | Equity Securities [Member] | Exchange Traded Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	563	2
Level I [Member] | Equity Securities [Member] | Fixed Maturity Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	0	0
Level I [Member] | Equity Securities [Member] | Common Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	796	601
Level I [Member] | Equity Securities [Member] | Private Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	0	0
Level I [Member] | Other Invested Assets, Current [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, current	10	21
Level I [Member] | Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Securities lending collateral	465	290
Total assets	21,307	17,783
Total liabilities	(1)	(17)
Level II [Member] | Fixed Maturities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	20,153	16,867
Level II [Member] | Fixed Maturities [Member] | United States Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	497	416
Level II [Member] | Fixed Maturities [Member] | Government Sponsored Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	131	108
Level II [Member] | Fixed Maturities [Member] | States, Municipalities And Political Subdivisions, Tax-Exempt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	4,742	4,785
Level II [Member] | Fixed Maturities [Member] | Corporate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	9,028	7,648
Level II [Member] | Fixed Maturities [Member] | Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	4,014	2,744
Level II [Member] | Fixed Maturities [Member] | Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	90	67
Level II [Member] | Fixed Maturities [Member] | Other Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	1,651	1,099
Level II [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	664	610
Level II [Member] | Equity Securities [Member] | Exchange Traded Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	0	0
Level II [Member] | Equity Securities [Member] | Fixed Maturity Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	631	557
Level II [Member] | Equity Securities [Member] | Common Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	33	53
Level II [Member] | Equity Securities [Member] | Private Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	0	0
Level II [Member] | Other Invested Assets, Current [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, current	0	0
Level II [Member] | Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	25	16
Derivative liabilities	(1)	(17)
Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Securities lending collateral	0	0
Total assets	631	623
Total liabilities	0	0
Level III [Member] | Fixed Maturities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	325	310
Level III [Member] | Fixed Maturities [Member] | United States Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Level III [Member] | Fixed Maturities [Member] | Government Sponsored Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Level III [Member] | Fixed Maturities [Member] | States, Municipalities And Political Subdivisions, Tax-Exempt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Level III [Member] | Fixed Maturities [Member] | Corporate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	311	287
Level III [Member] | Fixed Maturities [Member] | Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	3	6
Level III [Member] | Fixed Maturities [Member] | Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Level III [Member] | Fixed Maturities [Member] | Other Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	11	17
Level III [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	306	313
Level III [Member] | Equity Securities [Member] | Exchange Traded Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	0	0
Level III [Member] | Equity Securities [Member] | Fixed Maturity Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	0	0
Level III [Member] | Equity Securities [Member] | Common Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	0	0
Level III [Member] | Equity Securities [Member] | Private Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	306	313
Level III [Member] | Other Invested Assets, Current [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, current	0	0
Level III [Member] | Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	$ 0	$ 0

Fair Value (Reconciliation Of T

Fair Value (Reconciliation Of The Beginning And Ending Balances Of Assets Measured At Fair Value On A Recurring Basis Using Level III Inputs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 616	$ 646	$ 623	$ 537
Total gains (losses) recognized in net income	(8)	4	(12)	(227)
Total gains (losses) recognized in accumulated other comprehensive loss	12	(1)	14	(3)
Purchases	53	40	139	369
Sales	(28)	(5)	(59)	(21)
Settlements	(18)	(30)	(61)	(62)
Transfers into Level III	4	7	7	70
Transfers out of Level III	0	(15)	(20)	(17)
Ending balance	631	646	631	646
Change in unrealized losses included in net income related to assets still held	(4)	9	(4)	27
Corporate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	297	304	287	229
Total gains (losses) recognized in net income	(3)	0	(7)	1
Total gains (losses) recognized in accumulated other comprehensive loss	12	(1)	14	(3)
Purchases	28	32	91	94
Sales	(9)	(2)	(11)	(17)
Settlements	(18)	(30)	(58)	(60)
Transfers into Level III	4	6	4	65
Transfers out of Level III	0	(2)	(9)	(2)
Ending balance	311	307	311	307
Change in unrealized losses included in net income related to assets still held	0	0	0	0
Residential Mortgage-Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	3	4	6	5
Total gains (losses) recognized in net income	0	0	0	0
Total gains (losses) recognized in accumulated other comprehensive loss	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	(1)	(1)
Transfers into Level III	0	0	0	0
Transfers out of Level III	0	0	(2)	0
Ending balance	3	4	3	4
Change in unrealized losses included in net income related to assets still held	0	0	0	0
Other Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	11	26	17	16
Total gains (losses) recognized in net income	0	0	0	0
Total gains (losses) recognized in accumulated other comprehensive loss	0	0	0	0
Purchases	0	3	2	12
Sales	0	0	0	0
Settlements	0	0	(2)	(1)
Transfers into Level III	0	1	3	5
Transfers out of Level III	0	(13)	(9)	(15)
Ending balance	11	17	11	17
Change in unrealized losses included in net income related to assets still held	0	0	0	0
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	305	312	313	287
Total gains (losses) recognized in net income	(5)	4	(5)	(228)
Total gains (losses) recognized in accumulated other comprehensive loss	0	0	0	0
Purchases	25	5	46	263
Sales	(19)	(3)	(48)	(4)
Settlements	0	0	0	0
Transfers into Level III	0	0	0	0
Transfers out of Level III	0	0	0	0
Ending balance	306	318	306	318
Change in unrealized losses included in net income related to assets still held	$ (4)	$ 9	$ (4)	$ 27

Fair Value (Carrying And Estima

Fair Value (Carrying And Estimated Fair Values by Level Of Financial Instruments Not Recorded At Fair Value On Consolidated Balance Sheet) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, long-term	$ 3,914	$ 3,726
Short-term borrowings	710	1,145
Commercial paper	500	697
Notes	20,198	17,145
Convertible debentures	893	1,030
Fair Value, Recurring [Member] | Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, long-term	3,914	3,726
Short-term borrowings	0	0
Commercial paper	0	0
Notes	0	0
Convertible debentures	0	0
Fair Value, Recurring [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, long-term	0	0
Short-term borrowings	710	1,145
Commercial paper	500	697
Notes	20,198	17,145
Convertible debentures	893	1,030
Fair Value, Recurring [Member] | Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, long-term	0	0
Short-term borrowings	0	0
Commercial paper	0	0
Notes	0	0
Convertible debentures	0	0
Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, long-term	3,914	3,726
Short-term borrowings	710	1,145
Commercial paper	500	697
Notes	18,841	17,178
Convertible debentures	$ 179	$ 191

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income tax expense	$ 306	$ 282	$ 1,014	$ 1,200
Effective tax rate	20.60%	22.70%	20.70%	26.50%
Health Insurance Provider Fee, nondeductible expense		$ 76		$ 243

Retirement Benefits (Components

Retirement Benefits (Components Of Net Periodic (Benefit Credit) Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 2	$ 0	$ 6
Interest cost	15	14	47	41
Expected return on assets	(35)	(37)	(104)	(110)
Recognized actuarial loss	5	6	13	18
Settlement loss	4	6	8	19
Amortization of prior service cost (credit)	0	0	0	0
Net periodic benefit credit	(11)	(9)	(36)	(26)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	0	1	1
Interest cost	3	4	11	11
Expected return on assets	(6)	(6)	(17)	(18)
Recognized actuarial loss	1	1	2	3
Settlement loss	0	0	0	0
Amortization of prior service cost (credit)	(3)	(3)	(9)	(9)
Net periodic benefit credit	$ (4)	$ (4)	$ (12)	$ (12)

Retirement Benefits (Narrative)

Retirement Benefits (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 0	$ 7

Medical Claims Payable (Reconci

Medical Claims Payable (Reconciliation Of The Beginning And Ending Balances For Medical Claims Payable By Segment) (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Medical Claims Payable [Line Items]
Gross medical claims payable, beginning of period			$ 7,266			$ 7,814	$ 7,266	$ 7,814
Ceded medical claims payable, beginning of period			(34)			(105)	(34)	(105)
Net medical claims payable, beginning of period			7,232			7,709	7,232	7,709
Business combinations and purchase adjustments				$ 199				199
Current period net incurred medical claims							58,157	51,396
Prior periods redundancies							(437)	(858)
Total net incurred medical claims	$ 19,897	$ 19,484	18,339	17,411	$ 16,923	16,204	57,720	50,538
Net payments attributable to current period medical claims							49,751	44,511
Net payments attributable to prior periods medical claims							6,466	6,504
Total net payments							56,217	51,015
Short duration contract liability for unpaid claims and adjustment expense, Net	8,735			7,431			8,735	7,431
Ceded medical claims payable, end of period	35			37			35	37
Gross medical claims payable, end of period	8,770			7,468			8,770	7,468
Government Business Segment [Member]
Medical Claims Payable [Line Items]
Gross medical claims payable, beginning of period			4,680			4,431	4,680	4,431
Ceded medical claims payable, beginning of period			(24)			(27)	(24)	(27)
Net medical claims payable, beginning of period			4,656			4,404	4,656	4,404
Business combinations and purchase adjustments				199				199
Current period net incurred medical claims							39,171	33,664
Prior periods redundancies							(275)	(434)
Total net incurred medical claims	13,351	13,062	12,483	11,397	11,039	10,794	38,896	33,230
Net payments attributable to current period medical claims							33,474	29,236
Net payments attributable to prior periods medical claims							4,253	3,833
Total net payments							37,727	33,069
Short duration contract liability for unpaid claims and adjustment expense, Net	5,825			4,764			5,825	4,764
Ceded medical claims payable, end of period	27			27			27	27
Gross medical claims payable, end of period	5,852			4,791			5,852	4,791
Commercial Specialty Business Segment [Member]
Medical Claims Payable [Line Items]
Gross medical claims payable, beginning of period			2,586			3,383	2,586	3,383
Ceded medical claims payable, beginning of period			(10)			(78)	(10)	(78)
Net medical claims payable, beginning of period			2,576			3,305	2,576	3,305
Business combinations and purchase adjustments				0				0
Current period net incurred medical claims							18,986	17,732
Prior periods redundancies							(162)	(424)
Total net incurred medical claims	6,546	$ 6,422	$ 5,856	6,014	$ 5,884	$ 5,410	18,824	17,308
Net payments attributable to current period medical claims							16,277	15,275
Net payments attributable to prior periods medical claims							2,213	2,671
Total net payments							18,490	17,946
Short duration contract liability for unpaid claims and adjustment expense, Net	2,910			2,667			2,910	2,667
Ceded medical claims payable, end of period	8			10			8	10
Gross medical claims payable, end of period	$ 2,918			$ 2,677			$ 2,918	$ 2,677

Medical Claims Payable (Recon_2

Medical Claims Payable (Reconciliation Of Net Incurred Medical Claims To Benefit Expense) (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Reconciliation of net incurred medical claims to benefit expense [Line Items]
Total net incurred medical claims	$ 19,897	$ 19,484	$ 18,339	$ 17,411	$ 16,923	$ 16,204	$ 57,720	$ 50,538
Quality improvement and other claims expense	856	884	943	774	805	842	2,683	2,421
Benefit expense	20,753	20,368	19,282	18,185	17,728	17,046	60,403	52,959
Government Business Segment [Member]
Reconciliation of net incurred medical claims to benefit expense [Line Items]
Total net incurred medical claims	13,351	13,062	12,483	11,397	11,039	10,794	38,896	33,230
Commercial Specialty Business Segment [Member]
Reconciliation of net incurred medical claims to benefit expense [Line Items]
Total net incurred medical claims	$ 6,546	$ 6,422	$ 5,856	$ 6,014	$ 5,884	$ 5,410	$ 18,824	$ 17,308

Medical Claims Payable Medical

Medical Claims Payable Medical Claims Payable (Reconciliation of the Claims Development to the Claims Liability) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Net medical claims payable, end of period	$ 8,735	$ 7,232		$ 7,709
Ceded medical claims payable end of period	35	34	$ 37	105
Insurance lines other than short duration	207
Gross medical claims payable, end of period	8,977	7,454
Commercial Specialty Business Segment [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Net medical claims payable, end of period	2,910	2,576		3,305
Ceded medical claims payable end of period	8	10	10	78
Insurance lines other than short duration	0
Gross medical claims payable, end of period	2,918
Government Business Segment [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Net medical claims payable, end of period	5,825	4,656		4,404
Ceded medical claims payable end of period	27	$ 24	$ 27	$ 27
Insurance lines other than short duration	207
Gross medical claims payable, end of period	$ 6,059

Medical Claims Payable (Narrati

Medical Claims Payable (Narrative) (Details) $ in Millions	Sep. 30, 2019USD ($)
Short-duration Insurance Contracts, Claim Year 2019 [Member] | Commercial Specialty Business Segment [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 2,709
Short-duration Insurance Contracts, Claim Year 2019 [Member] | Government Business Segment [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	5,697
Short-duration Insurance Contracts, Claim Year 2018 [Member] | Commercial Specialty Business Segment [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	171
Short-duration Insurance Contracts, Claim Year 2018 [Member] | Government Business Segment [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	105
Short-duration Insurance Contracts, Claim Year 2017 and Prior [Member] | Commercial Specialty Business Segment [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	30
Short-duration Insurance Contracts, Claim Year 2017 and Prior [Member] | Government Business Segment [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 23

Debt (Convertible Debenture Det

Debt (Convertible Debenture Details) (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)$ / shares	Dec. 31, 2018USD ($)
Debt Instrument [Line Items]
Net debt carrying amount	$ 893	$ 1,030
Convertible Debt [Member]
Debt Instrument [Line Items]
Outstanding principal amount	267
Unamortized debt discount	85
Net debt carrying amount	179
Equity component carrying amount	$ 97
Conversion rate (shares of common stock per $1,000 of principal)	13.9250
Effective conversion price (per $1,000 of principal amount) per share | $ / shares	$ 71.8129

Debt (Narrative) (Details)

Debt (Narrative) (Details) - USD ($)	May 01, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 09, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 02, 2018	May 12, 2015
Debt Instrument [Line Items]
Repayments of Long-term Debt				$ 923,000,000	$ 1,393,000,000
Gain (Loss) on extinguishment of debt		$ 0	$ 1,000,000	1,000,000	(17,000,000)
Short-term borrowings		710,000,000		710,000,000					$ 1,145,000,000
Commercial paper		500,000,000		500,000,000					697,000,000
Equity Unit Purchase Agreements [Member]
Debt Instrument [Line Items]
Equity Units Issued											25,000,000
Equity Units, stated value per unit (whole dollars)											$ 50
Equity Units, ownership interest percentage in remarketable subordinated notes											5.00%
Debt instrument, face amount											$ 1,250,000,000
Equity Units Stock Purchase Contracts Settlement Rate	0.2412
Issuance of common stock under Equity Units stock purchase contracts, shares	6,000,000
Convertible Debt [Member]
Debt Instrument [Line Items]
Repurchased Face Amount				20,000,000
Repayments of Long-term Debt				73,000,000
Gain (Loss) on extinguishment of debt				1,000,000
Lines of Credit [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		600,000,000		600,000,000
Short-term borrowings		150,000,000		150,000,000					500,000,000
Federal Home Loan Bank Advances [Member]
Debt Instrument [Line Items]
Federal Home Loan Bank, advances, short-term		$ 560,000,000		$ 560,000,000					$ 645,000,000
Debt instrument interest rate		1.99%		1.99%					2.458%
Surplus Notes [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 25,000,000		$ 25,000,000					$ 25,000,000
Remarketable Subordinated Notes [Member]
Debt Instrument [Line Items]
Remarketable subordinated notes tendered, cash payment					4,000,000
Gain (Loss) on extinguishment of debt					$ (18,000,000)
Remarketable Subordinated Notes [Member] | Four Point One Zero One Percent Due Two Thousand Twenty Eight [Member]
Debt Instrument [Line Items]
Debt instrument, face amount										$ 1,250,000,000
Remarketable Subordinated Notes [Member] | Four Point Five Five Zero Percent Due Two Thousand Forty Eight [Member]
Debt Instrument [Line Items]
Debt instrument, face amount										$ 850,000,000
Remarketable Subordinated Notes [Member] | One Point Nine Zero Zero Percent Due Two Thousand Twenty Eight [Member]
Debt Instrument [Line Items]
Debt instrument, face amount											$ 1,000
Debt Instrument, Interest Rate, Stated Percentage											1.90%
Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Long-term Debt		18,816,000,000		18,816,000,000					17,153,000,000
Senior Unsecured Notes [Member] | Two Point Three Seven Five Due Two Thousand Twenty Five [Member]
Debt Instrument [Line Items]
Debt instrument, face amount						$ 850,000,000
Debt Instrument, Interest Rate, Stated Percentage						2.375%
Senior Unsecured Notes [Member] | Two Point Eight Seven Five Due Twenty Twenty Nine [Member]
Debt Instrument [Line Items]
Debt instrument, face amount						$ 825,000,000
Debt Instrument, Interest Rate, Stated Percentage						2.875%
Senior Unsecured Notes [Member] | Three Point Seven Zero Zero Due Twenty Forty Nine [Member]
Debt Instrument [Line Items]
Debt instrument, face amount						$ 825,000,000
Debt Instrument, Interest Rate, Stated Percentage						3.70%
Commercial Paper Program
Debt Instrument [Line Items]
Commercial paper authorized		3,500,000,000		3,500,000,000			$ 2,500,000,000
Commercial paper		500,000,000		500,000,000					$ 697,000,000
364-Day Facility [Member] | Senior Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		1,000,000,000		1,000,000,000
5-Year Facility [Member] | Senior Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 2,500,000,000		$ 2,500,000,000				$ 3,500,000,000

Commitments And Contingencies (

Commitments And Contingencies (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)
Commitments And Contingencies [Line Items]
Gross premium tax rate, state of California	2.35%
Merger Agreement, Termination Fee	$ 1,850
Minimum [Member]
Commitments And Contingencies [Line Items]
Estimate of possible loss on loss contingencies	0
Maximum [Member]
Commitments And Contingencies [Line Items]
Estimate of possible loss on loss contingencies	700
Anthem, Inc. v. Express Scripts, Inc. [Member]
Commitments And Contingencies [Line Items]
Proceeds originally received at time of divestiture	4,675
Anthem, Inc. v. Express Scripts, Inc. [Member] | Damages for Pharmacy Pricing [Member]
Commitments And Contingencies [Line Items]
Approximate amount of damages sought for breaches	14,800
Anthem, Inc. v. Express Scripts, Inc. [Member] | Damages for Operational Breaches [Member]
Commitments And Contingencies [Line Items]
Approximate amount of damages sought for breaches	$ 158

Capital Stock (Summary of Cash

Capital Stock (Summary of Cash Dividend Activity) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Capital [Abstract]
Declaration date	Jul. 23, 2019	Apr. 23, 2019	Jan. 29, 2019	Jul. 24, 2018	Apr. 24, 2018	Jan. 30, 2018
Record date	Sep. 10, 2019	Jun. 10, 2019	Mar. 18, 2019	Sep. 10, 2018	Jun. 8, 2018	Mar. 9, 2018
Payment date	Sep. 25, 2019	Jun. 25, 2019	Mar. 29, 2019	Sep. 25, 2018	Jun. 25, 2018	Mar. 23, 2018
Cash dividends per share	$ 0.80	$ 0.80	$ 0.80	$ 0.75	$ 0.75	$ 0.75
Total payment	$ 204	$ 206	$ 206	$ 195	$ 196	$ 192	$ 616	$ 583

Capital Stock (Summary of Share

Capital Stock (Summary of Share Repurchases) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	3 Months Ended						9 Months Ended
	Oct. 16, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Equity, Class of Treasury Stock [Line Items]
Shares repurchased								5.2	5
Average price per share								$ 270.42	$ 240.15
Aggregate cost		$ 644	$ 458	$ 294	$ 397	$ 401	$ 394	$ 1,396	$ 1,192
Authorization remaining at the end of the period		$ 4,098			$ 5,986			$ 4,098	$ 5,986
Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased	0.4
Average price per share	$ 238.71
Aggregate cost	$ 104
Authorization remaining at the end of the period	$ 3,994

Capital Stock (Summary of Stock

Capital Stock (Summary of Stock Option Activity) (Details) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)$ / sharesshares
Number of Shares [Roll Forward]
Outstanding at beginning of period, Number of Shares | shares	3.7
Granted, Number of Shares | shares	0.7
Exercised, Number of Shares | shares	(0.9)
Forfeited or expired, Number of Shares | shares	(0.1)
Outstanding at end of period, Number of Shares | shares	3.4
Exercisable at end of period, Number of Shares | shares	2.2
Weighted-Average Option Price Per Share [Roll Forward]
Outstanding at beginning of period, Weighted-Average Option Price per Share | $ / shares	$ 149.65
Granted, Weighted-Average Option Price per Share | $ / shares	306.74
Exercised, Weighted-Average Option Price per Share | $ / shares	127.92
Forfeited or expired, Weighted-Average Option Price per Share | $ / shares	238.81
Outstanding at end of period, Weighted-Average Option Price per Share | $ / shares	185.47
Exercisable at end of period, Weighted-Average Option Price per Share | $ / shares	$ 142.26
Outstanding at end of period, Weighted-Average Remaining Contractual Life	6 years 3 months 10 days
Exercisable at end of period, Weighted-Average Remaining Contractual Life	5 years 7 days
Outstanding at end of period, Aggregate Intrinsic Value | $	$ 233
Exercisable at end of period, Aggregate Intrinsic Value | $	$ 220

Capital Stock (Nonvested Restri

Capital Stock (Nonvested Restricted Stock Activity Including Restricted Stock Units) (Details) - $ / shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Restricted Stock Shares and Units [Roll Forward]
Nonvested at Beginning Balance, Restricted Stock Shares and Units			1.7
Granted, Restricted Stock Shares and Units	0	0	0.5	0.9
Vested, Restricted Stock Shares And Units			(0.8)
Forfeited, Restricted Stock Shares And Units			0
Nonvested at Ending Balance, Restricted Stock Shares and Units	1.4		1.4
Weighted-Average Grant Date Fair Value Per Share [Roll Forward]
Nonvested at Beginning Balance, Weighted-Average Grant Date Fair Value per Share			$ 183.32
Granted, Weighted-Average Grant Date Fair Value per Share			306.13	$ 233.27
Vested, Weighted-Average Grant Date Fair Value per Share			152.97
Forfeited, Weighted-Average Grant Date Fair Value per Share			243.77
Nonvested at Ending Balance, Weighted-Average Grant Date Fair Value per Share	$ 240.92		$ 240.92

Capital Stock (Fair Values of O

Capital Stock (Fair Values of Options Granted During The Period Estimated Using Weighted-Average Assumptions) (Details)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Capital [Abstract]
Risk-free interest rate	2.69%	2.90%
Volatility factor	25.00%	30.00%
Quarterly dividend yield	0.26%	0.323%
Weighted-average expected life (years)	4 years 4 months 24 days	3 years 8 months 12 days

Capital Stock (Schedule Of Weig

Capital Stock (Schedule Of Weighted-Average Fair Values Determined For The Periods) (Details) - $ / shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Capital [Abstract]
Options granted during the period	$ 68.69	$ 55.44
Restricted stock awards granted during the period	$ 306.13	$ 233.27

Capital Stock (Narrative) (Deta

Capital Stock (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Dec. 20, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Dec. 07, 2017
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Dividends Payable, Date to be Paid		Sep. 25, 2019	Jun. 25, 2019	Mar. 29, 2019	Sep. 25, 2018	Jun. 25, 2018	Mar. 23, 2018
Dividends Payable, Date of Record		Sep. 10, 2019	Jun. 10, 2019	Mar. 18, 2019	Sep. 10, 2018	Jun. 8, 2018	Mar. 9, 2018
Increase In Stock Repurchase Program Authorization									$ 5,000
Subsequent Event [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Dividends Payable, Amount Per Share	$ 0.80
Dividends Payable, Date to be Paid	Dec. 20, 2019
Dividends Payable, Date of Record	Dec. 5, 2019
2019 to 2021 [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross								0.2

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss (Reconciliation Of The Components Of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	$ 770	$ 170
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(54)	(289)
Investments, net pretax unrealized gains (losses) excluding non-credit component of other-than-temporary impairments	716	(119)
Deferred tax (liability) asset	(164)	24
Net unrealized gains (losses) on investments excluding non-credit component of other-than-temporary impairments	552	(95)
Non-credit component of other than temporary impairments on investments, unrealized losses	(5)	(2)
Non-credit component of other than temporary impairments on investments, deferred tax asset	1	0
Net unrealized non-credit component of other than temporary impairments on investments	(4)	(2)
Cash flow hedges, gross unrealized losses	(340)	(315)
Cash flow hedges, deferred tax asset	63	66
Net unrealized losses on cash flow hedges	(277)	(249)
Defined benefit pension plans, deferred net actuarial loss	(730)	(587)
Defined benefit pension plans, deferred prior service credits	(1)	(1)
Defined benefit pension plans, deferred tax asset	188	153
Net unrecognized periodic benefit costs for defined benefit pension plans	(543)	(435)
Postretirement benefit plans, deferred net actuarial loss	(57)	(75)
Postretirement beneft plans, prior service costs	25	37
Postretirement benefit plans, deferred tax asset	8	10
Net unrecognized periodic benefit costs for postretirement benefit plans	(24)	(28)
Foreign currency translation adjustments, gross unrealized losses	(4)	(2)
Foreign currency translation adjustments, deferred tax asset	1	0
Net unrealized losses on foreign currency translation adjustments	(3)	(2)
Accumulated other comprehensive loss	$ (299)	$ (811)	$ (986)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Other Comprehensive Income (Loss) Reclassification Adjustments) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net holding gain (loss) on investment securities arising during the period, net of tax	$ 119	$ (45)	$ 705	$ (378)
Reclassification adjustment for net realized loss (gain) on investment securities, net of tax	(3)	9	6	25
Total reclassification adjustment on investments	116	(36)	711	(353)
Non-credit component of other-than-temporary impairments on investments, net of tax	(1)	(2)	(2)	(2)
Cash flow hedges, holding gain (loss), net of tax	(34)	2	(31)	34
Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, net of tax	4	7	10	22
Foreign currency translation adjustment, net of tax	(1)	0	(1)	0
Net gain (loss) recognized in other comprehensive income, net of tax	$ 84	$ (29)	$ 687	$ (299)

Accumulated Other Comprehensi_5

Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income Reclassification Adjustments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) Reclassification Adjustments (Parantheticals) [Abstract]
Net holding gain (loss) on investment securities arising during the period, tax (expense) benefit	$ (35)	$ 12	$ (205)	$ 109
Reclassification adjustment for net realized loss (gain) on investment securities, tax (benefit) expense	1	(3)	(1)	(7)
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Loss, Net of Tax, Including Portion Attributable to Noncontrolling Interest, Available-for-sale Securities	0	2	0	2
Cash flow hedges, holding gain (loss), tax (expense) benefit	(2)	(1)	(2)	(9)
Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, tax expense	(1)	(2)	(3)	(7)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	0	0	0	(1)
Net gain (loss) recognized in other comprehensive income, tax (expense) benefit	$ (37)	$ 4	$ (211)	$ 83

Earnings Per Share (Denominator

Earnings Per Share (Denominator For Basic And Diluted Earnings Per Share) (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Denominator for basic earnings per share - weighted-average shares	255.2	259.5	256.3	258
Effect of dilutive securities – employee stock options, nonvested restricted stock awards, convertible debentures and equity units	4.8	5.9	4.8	6.3
Denominator for diluted earnings per share	260	265.4	261.1	264.3

Earnings Per Share (Narrative)

Earnings Per Share (Narrative) (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Weighted average shares excluded from denominator for diluted earnings per share because the stock options were anti-dilutive	0.7	0	0.6	0.4
Restricted stock units issued under stock incentive plan	0	0	0.5	0.9
Restricted stock units excluded from the denominator for diluted earnings per share			0.2	0.3

Segment Information (Financial

Segment Information (Financial Data By Reportable Segment) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Reportable segments operating revenues	$ 26,444	$ 22,980	$ 76,009	$ 68,037
Operating gain (loss)	1,528	1,249	4,901	4,676
Commercial & Specialty [Member]
Segment Reporting Information [Line Items]
Operating gain (loss)	930	834	3,511	3,284
Government Business [Member]
Segment Reporting Information [Line Items]
Operating gain (loss)	616	456	1,471	1,477
Other [Member]
Segment Reporting Information [Line Items]
Operating gain (loss)	(18)	(41)	(81)	(85)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Reportable segments operating revenues	(1,303)	(330)	(2,353)	(961)
Unaffiliated
Segment Reporting Information [Line Items]
Reportable segments operating revenues	26,444	22,980	76,009	68,037
Unaffiliated | Commercial & Specialty [Member]
Segment Reporting Information [Line Items]
Reportable segments operating revenues	9,284	8,933	28,093	26,939
Unaffiliated | Government Business [Member]
Segment Reporting Information [Line Items]
Reportable segments operating revenues	15,955	13,979	46,419	40,951
Unaffiliated | Other [Member]
Segment Reporting Information [Line Items]
Reportable segments operating revenues	1,205	68	1,497	147
Affiliated [Member]
Segment Reporting Information [Line Items]
Reportable segments operating revenues	0	0	0	0
Affiliated [Member] | Commercial & Specialty [Member]
Segment Reporting Information [Line Items]
Reportable segments operating revenues	0	0	0	0
Affiliated [Member] | Government Business [Member]
Segment Reporting Information [Line Items]
Reportable segments operating revenues	0	0	0	0
Affiliated [Member] | Other [Member]
Segment Reporting Information [Line Items]
Reportable segments operating revenues	$ 1,303	$ 330	$ 2,353	$ 961

Segment Information Segment Inf

Segment Information Segment Information (Major Product Revenues for Each Reportable Segment) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	$ 26,444	$ 22,980	$ 76,009	$ 68,037
Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	9,284	8,933	28,093	26,939
Government Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	15,955	13,979	46,419	40,951
Other Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	2,508	398	3,850	1,108
Segment Eliminations [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	(1,303)	(330)	(2,353)	(961)
Managed Care Products [Member] | Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	7,542	7,211	22,806	21,852
Managed Care Products [Member] | Government Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	15,847	13,860	46,111	40,610
Managed Care Services [Member] | Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	1,330	1,332	4,049	3,913
Managed Care Services [Member] | Government Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	108	119	308	341
Dental Vision Products And Services [Member] | Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	325	306	975	914
Other Products [Member] | Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	$ 87	$ 84	$ 263	$ 260

Segment Information (Reconcilia

Segment Information (Reconciliation Of Reportable Segments Operating Revenues To Total Revenues Reported In The Consolidated Statements Of Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting [Abstract]
Reportable segments operating revenues	$ 26,444	$ 22,980	$ 76,009	$ 68,037
Net investment income	242	250	737	708
Net realized gains on financial instruments	1	27	90	5
Other-than-temporary impairment losses recognized in income	(13)	(6)	(30)	(18)
Total revenues	$ 26,674	$ 23,251	$ 76,806	$ 68,732

Segment Information (Reconcil_2

Segment Information (Reconciliation Of Reportable Segments Operating Gain To Income Before Income Tax Expense Included In The Consolidated Statements Of Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting [Abstract]
Reportable segments operating gain	$ 1,528	$ 1,249	$ 4,901	$ 4,676
Net investment income	242	250	737	708
Net realized gains on financial instruments	1	27	90	5
Other-than-temporary impairment losses recognized in income	(13)	(6)	(30)	(18)
Interest expense	(185)	(188)	(556)	(564)
Amortization of other intangible assets	(84)	(91)	(256)	(265)
Gain (loss) on Extinguishment of Debt	0	1	1	(17)
Income before income tax expense	$ 1,489	$ 1,242	$ 4,887	$ 4,525

Segment Information Segment I_2

Segment Information Segment Information (Narrative) (Details)	9 Months Ended
	Sep. 30, 2019segment
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Number of Reportable Segments	3

Leases (Lease and Other Informa

Leases (Lease and Other Information) (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)
Operating Lease, Cost	$ 48	$ 138
Short-term Lease, Cost	9	33
Sublease Income	(4)	(12)
Lease, Cost	53	159
Operating Lease, Payments	43	132
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 33	$ 33
Operating Lease, Weighted Average Remaining Lease Term	6 years	6 years
Weighted Average Discount Rate, Percent	3.96%	3.96%
Other Noncurrent Assets [Member]
Operating Lease, Right-of-Use Asset	$ 577	$ 577
Other Current Liabilities [Member]
Operating Lease, Liability, Current	167	167
Other Noncurrent Liabilities [Member]
Operating Lease, Liability, Noncurrent	$ 473	$ 473

Leases (Reconciliation of Futur

Leases (Reconciliation of Future Lease Payments to Total Lease Liabilities) (Details) $ in Millions	Sep. 30, 2019USD ($)
Leases (Reconciliation of Future Lease Payments to Total Lease Liabilities) [Abstract]
Operating lease payments, 2019; excluding nine months ended September 30, 2019	$ 60
Operating lease payments, 2020	163
Operating lease payments, 2021	133
Operating lease payments, 2022	121
Operating lease payments, 2023	103
Operating lease payments, Thereafter	79
Total future minimum payments	659
Imputed Interest, Leases	(19)
Operating Lease Liabilities	$ 640

Leases (Narrative) (Details)

Leases (Narrative) (Details)	9 Months Ended
	Sep. 30, 2019USD ($)
Lessee, Operating Lease, Not yet Commenced, Description [Abstract]
Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract	12 years
Lessee, Operating Lease, Lease Not yet Commenced, Description	are expected to commence on various dates during 2020 and 2021 when the construction is complete and we take possession of the buildings
Lessee, Operating Lease, Lease Not Yet Commenced Expense	$ 147
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	1 year
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	15 years