Elevance Health (ELV) 10-Q 30 Apr 14 2014 Q1 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	3 Months Ended
	Mar. 31, 2014	Apr. 15, 2014
Document and Entity Information	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Trading Symbol	'WLP	'
Entity Registrant Name	'WellPoint, Inc.	'
Entity Central Index Key	'0001156039	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	279,672,290

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$1,971.20	$1,582.10
Investments available-for-sale, at fair value:	'	'
Fixed maturity securities (amortized cost of $17,600.8 and $16,826.7)	18,004	17,038.20
Equity securities (cost of $1,374.0 and $1,168.5)	1,963.50	1,735.50
Other invested assets, current	25.9	16.3
Accrued investment income	173.6	168.8
Premium and self-funded receivables	4,457.50	3,968.70
Other receivables	1,234	1,063.30
Income taxes receivable	0	235.7
Securities lending collateral	1,325	969.8
Deferred tax assets, net	234.5	383
Other current assets	2,417.60	1,677.50
Assets held for sale	0	906.9
Total current assets	31,806.80	29,745.80
Long-term investments available-for-sale, at fair value:	'	'
Fixed maturity securities (amortized cost of $504.6 and $455.9)	502.4	449.9
Equity securities (cost of $26.8 and $27.4)	31	31.3
Other invested assets, long-term	1,593.80	1,542.60
Property and equipment, net	1,811.70	1,801.50
Goodwill	16,916.70	16,917.20
Other intangible assets	8,387.30	8,441
Other noncurrent assets	635.8	645.2
Total assets	61,685.50	59,574.50
Liabilities and shareholders' equity	'	'
Medical claims payable	6,707.10	6,127.20
Reserves for future policy benefits	65.7	63.1
Other policyholder liabilities	2,020.40	2,073.20
Total policy liabilities	8,793.20	8,263.50
Unearned income	1,073	822.7
Accounts payable and accrued expenses	4,113.10	3,426.30
Accrued Income Taxes, Current	97.7	0
Security trades pending payable	177.5	95.2
Securities lending payable	1,324.60	969.7
Short-term borrowings	590	400
Current portion of long-term debt	518.7	518
Other current liabilities	1,805.90	1,674.70
Liabilities held for sale	0	181.4
Total current liabilities	18,493.70	16,351.50
Long-term debt, less current portion	13,932.10	13,573.60
Reserves for future policy benefits, noncurrent	738.9	723
Deferred tax liabilities, net	3,343.10	3,325.20
Other noncurrent liabilities	832.4	836
Total liabilities	37,340.20	34,809.30
Commitment and contingencies-Note 9	'	'
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 – 281,912,262 and 293,273,830	2.9	2.9
Additional paid-in capital	10,003.50	10,765.20
Retained earnings	14,011.50	13,813.90
Accumulated other comprehensive income	327.4	183.2
Total shareholders' equity	24,345.30	24,765.20
Total liabilities and shareholders' equity	$61,685.50	$59,574.50

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Available-for-sale fixed maturity securities investments, current, amortized cost	$17,600.80	$16,826.70
Available-for-sale equity securities investment, current, cost	1,374	1,168.50
Available-for-sale fixed maturity securities investments, long-term, amortized cost	504.6	455.9
Available-for-sale equity securities investments, long-term, cost	$26.80	$27.40
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	281,912,262	293,273,830
Common stock, shares outstanding	281,912,262	293,273,830

Consolidated_Statements_Of_Inc

Consolidated Statements Of Income (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Revenues	'	'
Premiums	$16,517	$16,435.60
Administrative fees	1,118.30	990.1
Other revenue	9.5	9.4
Total operating revenue	17,644.80	17,435.10
Net investment income	183.7	162
Net realized gains on investments	41.7	16.8
Other-than-temporary impairment losses on investments:	'	'
Total other-than-temporary impairment losses on investments	-10.8	-37.9
Portion of other-than-temporary impairment losses recognized in other comprehensive income	0	0
Other-than-temporary impairment losses recognized in income	-10.8	-37.9
Total revenues	17,859.40	17,576
Expenses	'	'
Benefit expense	13,664.60	13,748.70
Selling, general and administrative expense:	'	'
Selling expense	370.8	385.9
General and administrative expense	2,490.70	1,943.20
Total selling, general and administrative expense	2,861.50	2,329.10
Interest expense	146.2	153.5
Amortization of other intangible assets	54	62.2
Loss on extinguishment of debt	3	0
Total expenses	16,729.30	16,293.50
Income from continuing operations before income tax expense	1,130.10	1,282.50
Income tax expense	438.7	410.2
Income from continuing operations	691.4	872.3
Income from discontinued operations, net of tax	9.6	12.9
Net income	$701	$885.20
Net income per share	'	'
Basic - continuing operations (in dollars per share)	$2.43	$2.88
Basic - discontinued operations (in dollars per share)	$0.03	$0.04
Basic net income per share	$2.46	$2.92
Diluted - continuing operations (in dollars per share)	$2.37	$2.85
Diluted - discontinued operations (in dollars per share)	$0.03	$0.04
Diluted net income per share	$2.40	$2.89
Dividends per share	$0.44	$0.38

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]	'	'
Net income	$701	$885.20
Other comprehensive income, net of tax:	'	'
Change in net unrealized gains/losses on investments	140.3	34.5
Change in non-credit component of other-than-temporary impairment losses on investments	0.5	2.2
Change in net unrealized gains/losses on cash flow hedges	0.7	0.7
Change in net periodic pension and postretirement costs	2.9	6.8
Foreign currency translation adjustment, net of tax benefit of $0.0 and $0.5, respectively	-0.2	-0.8
Other comprehensive income	144.2	43.4
Total comprehensive income	$845.20	$928.60

Consolidated_Statements_Of_Cas

Consolidated Statements Of Cash Flows (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Operating activities	'	'
Net income	$701	$885.20
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Net realized gains on investments	-41.7	-16.8
Other-than-temporary impairment losses recognized in income	10.8	37.9
Loss on extinguishment of debt	3	0
Gain on disposal from discontinued operations	-3.2	0
Loss on disposal of assets	0.1	0.7
Deferred income taxes	85.2	9.1
Amortization, net of accretion	190.3	186.7
Depreciation expense	26.4	25.3
Impairment of property and equipment	2.1	0
Share-based compensation	38.8	21.5
Excess tax benefits from share-based compensation	-22.4	-4.2
Changes in operating assets and liabilities:	'	'
Receivables, net	-616	-397.7
Other invested assets	-14.6	-8.2
Other assets	-69.5	-58.6
Policy liabilities	545.6	70.9
Unearned income	250	-31.1
Accounts payable and accrued expenses	-137.3	-224
Other liabilities	107.4	35.1
Income taxes	356	435.6
Other, net	-24.5	-10.5
Net cash provided by operating activities	1,387.50	956.9
Investing activities	'	'
Purchases of fixed maturity securities	-3,084.80	-3,955.50
Proceeds from fixed maturity securities:	'	'
Sales	2,061.20	2,531.80
Maturities, calls and redemptions	284.3	490.8
Purchases of equity securities	-228.6	-29.2
Proceeds from sales of equity securities	30.3	87.4
Purchases of other invested assets	-35.4	-127.5
Proceeds from sales of other invested assets	25.6	7.6
Settlement of non-hedging derivatives	-46.2	-80.6
Changes in securities lending collateral	-354.9	-12.9
Proceeds from sale of subsidiary, net of cash sold	740	0
Purchases of property and equipment	-135.7	-107.5
Other, net	-0.1	0
Net cash used in investing activities	-744.3	-1,195.60
Financing activities	'	'
Net proceeds from commercial paper borrowings	379.4	260.3
Repayments of long-term borrowings	-24.2	-556.9
Proceeds from short-term borrowings	970	100
Repayments of short-term borrowings	-780	0
Changes in securities lending payable	354.9	12.8
Changes in bank overdrafts	75	30.4
Repurchase and retirement of common stock	-1,262.80	-340.2
Cash dividends	-123.4	-113.4
Proceeds from issuance of common stock under employee stock plans	130.1	23.7
Excess tax benefits from share-based compensation	22.4	4.2
Net cash used in financing activities	-258.6	-579.1
Effect of foreign exchange rates on cash and cash equivalents	-0.3	-1.5
Change in cash and cash equivalents	384.3	-819.3
Cash and cash equivalents, at beginning of period	1,586.90	2,484.60
Cash and cash equivalents, at end of period	1,971.20	1,665.30
Less cash and cash equivalents of discontinued operations at end of period	0	-5.7
Cash and cash equivalents of continuing operations at end of period	$1,971.20	$1,659.60

Consolidated_Statements_Of_Sha

Consolidated Statements Of Shareholders' Equity (USD $)	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
In Millions, unless otherwise specified
Balance at Dec. 31, 2012	$23,802.70	$3	$10,853.50	$12,647.10	$299.10
Balance (in shares) at Dec. 31, 2012	'	304.7	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'
Net income	885.2	'	'	885.2	'
Other comprehensive income (loss)	43.4	'	'	'	43.4
Repurchase and retirement of common stock	-343.5	0	-200.5	-143	'
Repurchase and retirement of common stock (in shares)	-5.5	-5.5	'	'	'
Convertible debenture tax adjustment	-4	'	-4	'	'
Dividends and dividend equivalents	-114.2	'	'	-114.2	'
Issuance of common stock under employee stock plans, net of related tax benefits	48.4	'	48.4	'	'
Issuance of common stock under employee stock plans, net of related tax benefits (in shares)	'	1.5	'	'	'
Balance at Mar. 31, 2013	24,318	3	10,697.40	13,275.10	342.5
Balance (in shares) at Mar. 31, 2013	'	300.7	'	'	'
Balance at Dec. 31, 2013	24,765.20	2.9	10,765.20	13,813.90	183.2
Balance (in shares) at Dec. 31, 2013	'	293.3	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'
Net income	701	'	'	701	'
Other comprehensive income (loss)	144.2	'	'	'	144.2
Settlement of equity options	-19.4	'	-19.4	'	'
Repurchase and retirement of common stock	-1,262.80	0	-884.3	-378.5	'
Repurchase and retirement of common stock (in shares)	-14.3	-14.3	'	'	'
Dividends and dividend equivalents	-124.9	'	'	-124.9	'
Issuance of common stock under employee stock plans, net of related tax benefits	142	0	142	'	'
Issuance of common stock under employee stock plans, net of related tax benefits (in shares)	'	2.9	'	'	'
Balance at Mar. 31, 2014	$24,345.30	$2.90	$10,003.50	$14,011.50	$327.40
Balance (in shares) at Mar. 31, 2014	'	281.9	'	'	'

Organization

Organization	3 Months Ended
	Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Organization	'
	Organization
	References to the terms “we”, “our”, “us”, “WellPoint” or the “Company” used throughout these Notes to Consolidated Financial Statements refer to WellPoint, Inc., an Indiana corporation, and unless the context otherwise requires, its direct and indirect subsidiaries.
	We are one of the largest health benefits companies in terms of medical membership in the United States, serving 36.9 medical members through our affiliated health plans and approximately 66.8 individuals through our subsidiaries as of March 31, 2014. We offer a broad spectrum of network-based managed care plans to large and small employer, individual, Medicaid and Medicare markets. Our managed care plans include: preferred provider organizations, or PPOs; health maintenance organizations, or HMOs; point-of-service, or POS, plans; traditional indemnity plans and other hybrid plans, including consumer-driven health plans, or CDHPs; 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, underwriting, 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 behavioral health benefit services, dental, vision, life and disability insurance benefits, radiology benefit management, analytics-driven personal health care guidance and long-term care insurance. We also provide services to the Federal Government in connection with the Federal Employee Program, or FEP, and various Medicare programs. We also sold contact lenses, eyeglasses and other ocular products through our 1-800 CONTACTS, Inc., or 1-800 CONTACTS, business, which was divested on January 31, 2014.
	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 (as BCBS in 10 New York City metropolitan and surrounding counties, and as Blue Cross or BCBS in selected upstate counties only), 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, Blue Cross and Blue Shield of Georgia, and Empire Blue Cross Blue Shield, or Empire Blue Cross (in our New York service areas). We also conduct business through our AMERIGROUP Corporation, or Amerigroup, subsidiary in Florida, Georgia, Kansas, Louisiana, Maryland, Nevada, New Jersey, New York, Tennessee, Texas and Washington. We also serve customers throughout the country as HealthLink, UniCare, and in certain Arizona, California, Nevada, New York and Virginia markets, through our CareMore Health Group, Inc., or CareMore, subsidiary. We are licensed to conduct insurance operations in all 50 states through our subsidiaries.

Basis_Of_Presentation_and_Sign

Basis Of Presentation and Significant Accounting Policies	3 Months Ended
	Mar. 31, 2014
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 2013 Annual Report on Form 10-K, unless the information contained in those disclosures materially changed or is required by GAAP. Unless otherwise specified, all financial information presented in the accompanying consolidated financial statements and in the notes to consolidated financial statements relates only to our continuing operations, other than cash flows presented on the consolidated statements of cash flows. 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 months ended March 31, 2014 and 2013 have been recorded. The results of operations for the three months ended March 31, 2014 are not necessarily indicative of the results that may be expected for the full year ending December 31, 2014. These unaudited consolidated financial statements should be read in conjunction with our audited consolidated financial statements for the year ended December 31, 2013 included in our 2013 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.
	Revenue Recognition: Premiums for fully-insured contracts are recognized as revenue over the period insurance coverage is provided, net of amounts recognized for minimum medical loss ratio rebates, if applicable, and the risk adjustment, reinsurance, and risk corridor premium stabilization programs of the Patient Protection and Affordable Care Act and the Health Care and Education Reconciliation Act of 2010. Premiums related to the unexpired contractual coverage periods are reflected in the accompanying consolidated balance sheets as unearned income. Premiums include revenue from retrospectively rated contracts where revenue is based on the estimated ultimate loss experience of the contract. Premium revenue includes an adjustment for retrospectively rated refunds based on an estimate of incurred claims. Premium rates for certain lines of business are subject to approval by the Department of Insurance of each respective state.
	Administrative fees 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. In addition, administrative fees include amounts received for the administration of Medicare or certain other government programs. Under our self-funded arrangements, revenue is recognized as administrative services are performed. All benefit payments under these programs are excluded from benefit expense.
	Adoption of New Accounting Pronouncement: Effective January 1, 2014, we adopted the provisions of Accounting Standards Update No. 2011-06, Other Expenses (Topic 720): Fees Paid to the Federal Government by Health Insurers (a consensus of the FASB Emerging Issues Task Force), or ASU 2011-06. The Patient Protection and Affordable Care Act and the Health Care and Education Reconciliation Act of 2010, or collectively, Health Care Reform, imposes a mandatory annual Health Insurance Provider Fee, or HIP Fee, on health insurers that write certain types of health insurance on U.S. risks. The annual HIP Fee is allocated to health insurers based on the ratio of the amount of an insurer's net premium revenues written during the preceding calendar year to the amount of health insurance for all U.S. health risk for those certain lines of business written during the preceding calendar year. This fee is non-deductible for federal income tax purposes. The total amount to be collected from allocations to health insurers in 2014 is $8,000.0, and we estimate our portion of the fee for 2014 to be approximately $920.0. ASU 2011-06 addresses how this fee should be recognized and classified in the financial statements of health insurers. In accordance with ASU 2011-06, we recorded our estimated liability for the fee in full at the beginning of the year with a corresponding deferred cost that is being amortized to expense on a straight-line basis, and we recognized $230.0 as general and administrative expense related to the fee for the three months ended March 31, 2014. The final calculation and payment of the fee will occur in the third quarter of 2014.
	Reclassifications: Certain prior period amounts have been reclassified to conform to the current period presentation.

Business_Acquisitions_and_Dive

Business Acquisitions and Divestitures	3 Months Ended
	Mar. 31, 2014
Business Divestiture [Abstract]	'
Business Divestiture	'
	Business Divestiture
	In December 2013, we entered into a definitive agreement to sell our 1-800 CONTACTS business to the private equity firm Thomas H. Lee Partners, L.P. Additionally, we entered into an asset purchase agreement with Luxottica Group to sell our glasses.com related assets (collectively, 1-800 CONTACTS). The operating results for 1-800 CONTACTS are reported as discontinued operations in the accompanying consolidated statements of income. These results were previously reported in the Commercial and Specialty Business segment. Additionally, the assets and liabilities of 1-800-CONTACTS are reported as held for sale in the accompanying consolidated balance sheets as of December 31, 2013. The sale was completed on January 31, 2014 and did not result in any material difference to the loss on disposal from discontinued operations recorded during the year ended December 31, 2013.

Investments

Investments	3 Months Ended
	Mar. 31, 2014
Investments [Abstract]	'
Investments	'
	Investments
	We evaluate our investment securities for other-than-temporary declines based on qualitative and quantitative factors. Other-than-temporary impairment losses recognized in income totaled $10.8 and $37.9 for the three months ended March 31, 2014 and 2013, respectively. There were no individually significant other-than-temporary impairment losses on investments by issuer during the three months ended March 31, 2014 and 2013. We continue to review our investment portfolios under our impairment review policy. Given the current market conditions and the significant judgments involved, there is a continuing risk that further declines in fair value may occur and additional material other-than-temporary impairment losses on investments may be recorded in future periods.
	A summary of current and long-term investments, available-for-sale, at March 31, 2014 and December 31, 2013 is as follows:
																				Non-Credit
																				Component of
																				Other-Than-
																				Temporary
																				Impairments
		Cost or			Gross			Gross Unrealized Losses								Estimated				Recognized in
		Amortized			Unrealized											Fair Value				AOCI
		Cost			Gains			Less than				12 Months
								12 Months				or Greater
	March 31, 2014:
	Fixed maturity securities:
	United States Government securities	$	460.2		$	2.7		$	(1.3	)		$	—			$	461.6			$	—
	Government sponsored securities	168.6			0.6			(0.5		)		(0.5		)		168.2				—
	States, municipalities and political subdivisions, tax-exempt	5,801.90			244.4			(33.3		)		(9.5		)		6,003.50				—
	Corporate securities	8,338.40			232.4			(54.8		)		(14.1		)		8,501.90				—
	Options embedded in convertible securities	97.6			—			—				—				97.6				—
	Residential mortgage-backed securities	2,160.00			53.9			(26.8		)		(5.5		)		2,181.60				—
	Commercial mortgage-backed securities	509.4			11.1			(1.1		)		(0.2		)		519.2				—
	Other debt securities	569.3			7.1			(2.8		)		(0.8		)		572.8				—
	Total fixed maturity securities	18,105.40			552.2			(120.6		)		(30.6		)		18,506.40				$	—
	Equity securities	1,400.80			604.3			(10.6		)		—				1,994.50
	Total investments, available-for-sale	$	19,506.20		$	1,156.50		$	(131.2	)		$	(30.6	)		$	20,500.90
	December 31, 2013:
	Fixed maturity securities:
	United States Government securities	$	300.8		$	2.5		$	(3.4	)		$	—			$	299.9			$	—
	Government sponsored securities	174.4			0.4			(1.3		)		—				173.5				—
	States, municipalities and political subdivisions, tax-exempt	5,899.50			202.9			(90.1		)		(9.6		)		6,002.70				(0.6		)
	Corporate securities	7,614.10			205.2			(95.2		)		(15.5		)		7,708.60				(0.1		)
	Options embedded in convertible securities	89.2			—			—				—				89.2				—
	Residential mortgage-backed securities	2,269.40			48			(41.4		)		(7.1		)		2,268.90				—
	Commercial mortgage-backed securities	479			10.5			(2.6		)		(0.3		)		486.6				—
	Other debt securities	456.2			5.8			(2.5		)		(0.8		)		458.7				(0.1		)
	Total fixed maturity securities	17,282.60			475.3			(236.5		)		(33.3		)		17,488.10				$	(0.8	)
	Equity securities	1,195.90			578.9			(8.0		)		—				1,766.80
	Total investments, available-for-sale	$	18,478.50		$	1,054.20		$	(244.5	)		$	(33.3	)		$	19,254.90
	At March 31, 2014, we owned $2,700.8 of mortgage-backed securities and $501.5 of asset-backed securities out of a total available-for-sale investment portfolio of $20,500.9. These securities included sub-prime and Alt-A securities with fair values of $30.0 and $98.8, respectively. These sub-prime and Alt-A securities had accumulated net unrealized gains of $1.3 and $7.1, respectively. The average credit rating of the sub-prime and Alt-A securities was “BB” and “CCC”, respectively.
	The following tables summarize for fixed maturity securities and equity securities in an unrealized loss position at March 31, 2014 and December 31, 2013, the aggregate fair value and gross unrealized loss by length of time those securities have been continuously in an unrealized loss position:
		Less than 12 Months									12 Months or Greater
	(Securities are whole amounts)	Number of		Estimated			Gross				Number of			Estimated				Gross
		Securities		Fair Value			Unrealized				Securities			Fair Value				Unrealized
							Loss											Loss
	March 31, 2014:
	Fixed maturity securities:
	United States Government securities	26		$	300.2		$	(1.3	)		—			$	—			$	—
	Government sponsored securities	15		28.8			(0.5		)		5			17				(0.5		)
	States, municipalities and political subdivisions, tax-exempt	496		1,351.00			(33.3		)		73			168				(9.5		)
	Corporate securities	1,215		2,198.90			(54.8		)		102			127.9				(14.1		)
	Residential mortgage-backed securities	490		985.9			(26.8		)		74			115.1				(5.5		)
	Commercial mortgage-backed securities	37		112.4			(1.1		)		4			4.8				(0.2		)
	Other debt securities	61		177.7			(2.8		)		19			17.1				(0.8		)
	Total fixed maturity securities	2,340		5,154.90			(120.6		)		277			449.9				(30.6		)
	Equity securities	505		131.8			(10.6		)		—			—				—
	Total fixed maturity and equity securities	2,845		$	5,286.70		$	(131.2	)		277			$	449.9			$	(30.6	)
	December 31, 2013:
	Fixed maturity securities:
	United States Government securities	27		$	179.2		$	(3.4	)		—			$	—			$	—
	Government sponsored securities	22		73.4			(1.3		)		—			—				—
	States, municipalities and political subdivisions, tax-exempt	806		2,070.90			(90.1		)		42			82.4				(9.6		)
	Corporate securities	1,448		2,586.60			(95.2		)		107			81.3				(15.5		)
	Residential mortgage-backed securities	605		1,243.00			(41.4		)		80			116.2				(7.1		)
Commercial mortgage-backed securities	52		177.7			(2.6		)		4			5.6				(0.3		)
Other debt securities	65		185.3			(2.5		)		17			16.2				(0.8		)
Total fixed maturity securities	3,025		6,516.10			(236.5		)		250			301.7				(33.3		)
Equity securities	426		120.8			(8.0		)		—			—				—
Total fixed maturity and equity securities	3,451		$	6,636.90		$	(244.5	)		250			$	301.7			$	(33.3	)
The amortized cost and fair value of fixed maturity securities at March 31, 2014, 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			Estimated
	Cost			Fair Value
Due in one year or less	$	444		$	447.4
Due after one year through five years	4,580.90			4,714.90
Due after five years through ten years	5,077.60			5,230.70
Due after ten years	5,333.50			5,412.60
Mortgage-backed securities	2,669.40			2,700.80
Total available-for-sale fixed maturity securities	$	18,105.40		$	18,506.40
Proceeds from fixed maturity securities, equity securities and other invested assets and the related gross realized gains and gross realized losses for the three months ended March 31, 2014 and 2013 are as follows:
	Three Months Ended
	March 31
	2014			2013
Proceeds	$	2,401.40		$	3,117.60
Gross realized gains	82.9			107
Gross realized losses	41.2			90.2
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.

Fair_Value

Fair Value	3 Months Ended
	Mar. 31, 2014
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'
Fair Value	'
	Fair Value
	Assets and liabilities recorded at fair value in the 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 Financial Accounting Standards Board, or 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 the 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. United States Government securities represent Level I securities, while Level II securities primarily include corporate securities, securities from states, municipalities and political subdivisions and mortgage-backed securities. For securities not actively traded, the third party 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 third party pricing services’ qualifications and procedures used to determine fair values. In addition, we periodically review the third party 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, that 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, available-for-sale: Fair values of equity securities are generally designated as Level I and are based on quoted market prices. 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, or EBITDA, 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. 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 market observable inputs for similar derivative transactions.
	Long-term receivable: Fair value is estimated based on discounted cash flow analysis using assumptions for inputs such as expected cash flow and discount rates that are not observable in the markets.
	A summary of fair value measurements by level for assets and liabilities measured at fair value on a recurring basis at March 31, 2014 and December 31, 2013 is as follows:
		Level I			Level II			Level III			Total
	March 31, 2014:
	Assets:
	Cash equivalents	$	612.4		$	—		$	—		$	612.4
	Investments available-for-sale:
	Fixed maturity securities:
	United States Government securities	461.6			—			—			461.6
	Government sponsored securities	—			168.2			—			168.2
	States, municipalities and political subdivisions, tax-exempt	—			6,003.50			—			6,003.50
	Corporate securities	12			8,375.90			114			8,501.90
	Options embedded in convertible debt securities	—			97.6			—			97.6
	Residential mortgage-backed securities	—			2,181.60			—			2,181.60
	Commercial mortgage-backed securities	—			516.1			3.1			519.2
	Other debt securities	71.3			486.7			14.8			572.8
	Total fixed maturity securities	544.9			17,829.60			131.9			18,506.40
	Equity securities	1,766.20			185.1			43.2			1,994.50
	Other invested assets, current	25.9			—			—			25.9
	Securities lending collateral	532			793			—			1,325.00
	Derivatives excluding embedded options (reported with other assets)	—			29			—			29
	Long-term receivable (reported with other assets)	—			—			21.6			21.6
	Total assets	$	3,481.40		$	18,836.70		$	196.7		$	22,514.80
	Liabilities:
	Derivatives excluding embedded options (reported with other liabilities)	$	—		$	(20.9	)	$	—		$	(20.9	)
	Total liabilities	$	—		$	(20.9	)	$	—		$	(20.9	)
	December 31, 2013:
	Assets:
	Cash equivalents	$	632.3		$	—		$	—		$	632.3
	Investments available-for-sale:
	Fixed maturity securities:
	United States Government securities	299.9			—			—			299.9
	Government sponsored securities	—			173.5			—			173.5
	States, municipalities and political subdivisions, tax-exempt	—			6,002.70			—			6,002.70
	Corporate securities	—			7,593.40			115.2			7,708.60
	Options embedded in convertible securities	—			89.2			—			89.2
	Residential mortgage-backed securities	—			2,268.90			—			2,268.90
	Commercial mortgage-backed securities	—			480.1			6.5			486.6
	Other debt securities	35.6			408.3			14.8			458.7
	Total fixed maturity securities	335.5			17,016.10			136.5			17,488.10
	Equity securities	1,475.70			249.7			41.4			1,766.80
	Other invested assets, current	16.3			—			—			16.3
	Securities lending collateral	408.5			561.3			—			969.8
	Derivatives excluding embedded options (reported with other assets)	—			58.4			—			58.4
	Total assets	$	2,868.30		$	17,885.50		$	177.9		$	20,931.70
	Liabilities:
	Derivatives excluding embedded options (reported with other liabilities)	$	—		$	(20.7	)	$	—		$	(20.7	)
	Total liabilities	$	—		$	(20.7	)	$	—		$	(20.7	)
	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 March 31, 2014 and 2013 is as follows:
		Corporate			Residential			Commercial			Other Debt			Equity			Long-term Receivable		Total
Securities			Mortgage-			Mortgage-			Securities			Securities
			backed			backed
			Securities			Securities
Three Months Ended March 31, 2014:
Beginning balance at January 1, 2014	$	115.2		$	—		$	6.5		$	14.8		$	41.4		$	—	$	177.9
Total gains (losses):
Recognized in net income	(3.3		)	—			—			—			(0.3		)	21.6		18
Recognized in accumulated other comprehensive income	3.1			—			—			0.2			(5.8		)	—		(2.5		)
Purchases	9.3			—			—			—			9			—		18.3
Sales	(1.7		)	—			—			—			(1.1		)	—		(2.8		)
Settlements	(2.1		)	—			(3.4		)	(0.2		)	—			—		(5.7		)
Transfers into Level III	—			—			—			—			—			—		—
Transfers out of Level III	(6.5		)	—			—			—			—			—		(6.5		)
Ending balance at March 31, 2014	$	114		$	—		$	3.1		$	14.8		$	43.2		$	21.6	$	196.7
Change in unrealized losses included in net income related to assets still held for the three months ended March 31, 2014	$	(4.0	)	$	—		$	—		$	—		$	(0.3	)	$	—	$	(4.3	)
Three Months Ended March 31, 2013:
Beginning balance at January 1, 2013	$	121.1		$	4.3		$	—		$	3.9		$	26.2		$	—	$	155.5
Total gains (losses):
Recognized in net income	0.3			—			—			—			0.6			—		0.9
Recognized in accumulated other comprehensive income	(0.6		)	—			—			0.2			(0.9		)	—		(1.3		)
Purchases	9.6			—			—			—			0.4			—		10
Sales	—			—			—			—			(2.5		)	—		(2.5		)
Settlements	(9.1		)	(1.6		)	—			(0.2		)	—			—		(10.9		)
Transfers into Level III	—			13.1			—			—			—			—		13.1
Transfers out of Level III	—			(2.9		)	—			—			—			—		(2.9		)
Ending balance at March 31, 2013	$	121.3		$	12.9		$	—		$	3.9		$	23.8		$	—	$	161.9
Change in unrealized losses included in net income related to assets still held for the three months ended March 31, 2013	$	—		$	—		$	—		$	—		$	(1.4	)	$	—	$	(1.4	)
Transfers between levels, if any, are recorded as of the beginning of the reporting period. There were no material transfers between levels during the three months ended March 31, 2014 or 2013.
There were no material assets or liabilities measured at fair value on a nonrecurring basis during the three months ended March 31, 2014 or 2013.
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 only one quoted price 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. When broker quotes are used, we generally obtain only one broker quote per security. As we are responsible for the determination of fair value, we perform monthly analysis on the prices received from third parties 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 third party pricing services engaged and the valuation techniques and inputs used. Our analysis includes a review of month-to-month price fluctuations. If unusual fluctuations are noted in this review, we may obtain additional information from other pricing services to validate the quoted price. There were no adjustments to quoted market prices obtained from third party pricing services during the three months ended March 31, 2014 or 2013.
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 the 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 the consolidated balance sheets for cash, accrued investment income, premium and self-funded receivables, other receivables, unearned income, accounts payable and accrued expenses, income taxes receivable/payable, 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, assumptions and inputs were used to estimate the fair value of each class of financial instrument that is recorded at its carrying value on the 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 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 – 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 March 31, 2014 and December 31, 2013 are as follows:
	Carrying			Fair Value
	Value			Level I			Level II			Level III			Total
March 31, 2014
Assets:
Other invested assets, long-term	$	1,593.80		$	—		$	—		$	1,593.80		$	1,593.80
Liabilities:
Debt:
Short-term borrowings	590			—			590			—			590
Commercial paper	758.6			—			758.6			—			758.6
Notes	12,724.10			—			13,285.10			—			13,285.10
Convertible debentures	968.1			—			2,192.80			—			2,192.80
December 31, 2013
Assets:
Other invested assets, long-term	$	1,542.60		$	—		$	—		$	1,542.60		$	1,542.60
Liabilities:
Debt:
Short-term borrowings	400			—			400			—			400
Commercial paper	379.2			—			379.2			—			379.2
Notes	12,746.40			—			13,014.30			—			13,014.30
Convertible debentures	966			—			2,030.60			—			2,030.60

Retirement_Benefits

Retirement Benefits	3 Months Ended
	Mar. 31, 2014
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]	'
Retirement Benefits	'
	Retirement Benefits
	The components of net periodic (credit) benefit cost included in the consolidated statements of income for the three months ended March 31, 2014 and 2013 are as follows:
		Pension Benefits						Other Benefits
		2014			2013			2014			2013
	Service cost	$	3.3		$	3.6		$	0.8		$	1.6
	Interest cost	18.5			16.7			6.6			5.6
	Expected return on assets	(34.4		)	(33.3		)	(5.8		)	(5.5		)
	Recognized actuarial loss	5.3			8.6			2.3			2.8
	Settlement loss	1.1			3.4			—			—
	Amortization of prior service credit	(0.2		)	(0.2		)	(3.6		)	(3.3		)
	Net periodic (credit) benefit cost	$	(6.4	)	$	(1.2	)	$	0.3		$	1.2
	For the year ending December 31, 2014, no material contributions are expected to be necessary to meet the Employee Retirement Income Security Act, or ERISA, required funding levels; however, we may elect to make discretionary contributions up to the maximum amount deductible for income tax purposes. No contributions were made to our retirement benefit plans during the three months ended March 31, 2014 or 2013.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	During the three months ended March 31, 2014 and 2013, we recognized income tax expense of $438.7 and $410.2, respectively, which represents effective tax rates of 38.8% and 32.0%, respectively. The increase in income tax expense and the effective tax rate in 2014 was primarily due to the non-tax deductible HIP Fee effective January 1, 2014 resulting in additional expense of $80.5, partially offset by lower income before income taxes, favorable discrete tax adjustments related to state income tax audits including refund claims filed, and adjustments to state deferred tax liabilities resulting from a decrease in the Indiana statutory income tax rate. The lower effective rate in the three months ended March 31, 2013 resulted primarily from the inclusion of Amerigroup in our state apportionment calculations, which produced a lower effective state tax rate.

Debt

Debt	3 Months Ended
	Mar. 31, 2014
Debt Instruments [Abstract]	'
Debt	'
	Debt
	We generally issue senior unsecured notes for long-term borrowing purposes. At March 31, 2014, we had $12,699.2 outstanding under these notes. During the three months ended March 31, 2014, we repurchased $21.2 of outstanding principal balance of certain senior unsecured notes, plus applicable premium for early redemption plus accrued and unpaid interest, for cash totaling $24.2. We recognized a loss on extinguishment of debt of $3.0 for the repurchase of these notes.
	We have an unsecured surplus note with an outstanding principal balance of $24.9 at March 31, 2014.
	We have a senior revolving credit facility, or the Facility, with certain lenders for general corporate purposes. The Facility, as amended, provides credit up to $2,000.0, and matures on September 29, 2016. There were no amounts outstanding under this Facility as of March 31, 2014 or at any time during the three months then ended.
	We have an authorized commercial paper program of up to $2,500.0, the proceeds of which may be used for general corporate purposes. At March 31, 2014, we had $758.6 outstanding under this program.
	We have issued senior 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. We have accounted for the Debentures in accordance with the cash conversion guidance in FASB guidance for debt with conversion and other options. As a result, the value of the embedded conversion option has been bifurcated from its debt host and recorded as a component of “additional paid-in capital” (net of deferred taxes and equity issuance costs) in our consolidated balance sheets. The following table summarizes at March 31, 2014 the related balances, conversion rate and conversion price of the Debentures:
	Outstanding principal amount	$	1,500.00
	Unamortized debt discount	531.9
	Net debt carrying amount	968.1
	Equity component carrying amount	543.6
	Conversion rate (shares of common stock per $1,000 of principal amount)	13.3135
	Effective conversion price (per $1,000 of principal amount)	$	75.1113

Commitments_And_Contingencies

Commitments And Contingencies	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments And Contingencies	'
	Commitments and Contingencies
	Litigation
	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.
	We are defending a certified class action filed as a result of the 2001 demutualization of Anthem Insurance Companies, Inc., or AICI. The lawsuit names AICI as well as Anthem, Inc., or Anthem, n/k/a WellPoint, Inc., and is captioned Ronald Gold, et al. v. Anthem, Inc. et al. AICI’s 2001 Plan of Conversion, or the Plan, provided for the conversion of AICI from a mutual insurance company into a stock insurance company pursuant to Indiana law. Under the Plan, AICI distributed the fair value of the company at the time of conversion to its Eligible Statutory Members, or ESMs, in the form of cash or Anthem common stock in exchange for their membership interests in the mutual company. Plaintiffs in Gold allege that AICI distributed value to the wrong ESMs. Cross motions for summary judgment were granted in part and denied in part on July 26, 2006 with regard to the issue of sovereign immunity asserted by co-defendant, the state of Connecticut, or the State. The trial court also denied our motion for summary judgment as to plaintiffs’ claims on January 10, 2005. The State appealed the denial of its motion to the Connecticut Supreme Court. We filed a cross-appeal on the sovereign immunity issue. On May 11, 2010, the Court reversed the judgment of the trial court denying the State’s motion to dismiss the plaintiff’s claims under sovereign immunity and dismissed our cross-appeal. The case was remanded to the trial court for further proceedings. Plaintiffs’ motion for class certification was granted on December 15, 2011. We and the plaintiffs filed renewed cross-motions for summary judgment on January 24, 2013. Argument on the renewed motions was held on April 19, 2013. On August 19, 2013, the trial court denied plaintiffs' motion for summary judgment. The trial court deferred a final ruling on our motion for summary judgment, instead requesting supplemental argument which occurred on November 7, 2013. On March 6, 2014, the trial court denied our motion for summary judgment finding that an issue of material fact existed. Trial has been scheduled to commence on October 14, 2014. We intend to vigorously defend the Gold lawsuit; however, its ultimate outcome cannot be presently determined.
	We are currently a defendant in eleven putative class actions relating to out-of-network, or OON, reimbursement that were consolidated into a single multi-district lawsuit called In re WellPoint, Inc. Out-of-Network “UCR” Rates Litigation that is pending in the United States District Court for the Central District of California. The lawsuits were filed in 2009. The plaintiffs include current and former members on behalf of a putative class of members who received OON services for which the defendants paid less than billed charges, the American Medical Association, four state medical associations, OON physicians, chiropractors, clinical psychologists, podiatrists, psychotherapists, the American Podiatric Association, California Chiropractic Association and the California Psychological Association on behalf of a putative class of all physicians and all non-physician health care providers. The plaintiffs have filed several amended complaints alleging that the defendants violated the Racketeer Influenced and Corrupt Organizations Act, or RICO, the Sherman Antitrust Act, ERISA, federal regulations, and state law by using an OON reimbursement database called Ingenix and in our use of non-Ingenix OON reimbursement methodologies. We have filed motions to dismiss in response to each of those amended complaints. Our motions to dismiss have been granted in part and denied in part by the court. The most recent pleading filed by the plaintiffs is a Fourth Amended Complaint to which we filed a motion to dismiss most, but not all, of the claims. In July 2013 the court issued an order granting in part and denying in part our motion. The court held that the state and federal anti-trust claims along with the RICO claims should be dismissed in their entirety with prejudice. The court further found that the ERISA claims, to the extent they involved non-Ingenix methodologies, along with those that involved our alleged non-disclosures should be dismissed with prejudice. The court also dismissed most of the plaintiffs’ state law claims with prejudice. The only claims that remain after the court’s decision are an ERISA benefits claim relating to claims priced based on Ingenix, a breach of contract claim on behalf of one subscriber plaintiff, a breach of implied covenant claim on behalf of one plaintiff, and one subscriber plaintiff’s claim under the California Unfair Competition Law. The plaintiffs filed a motion for reconsideration of the motion to dismiss order, which the court granted in part and denied in part. The court ruled that the plaintiffs adequately allege that one Georgia provider plaintiff is deemed to have exhausted administrative remedies regarding non-Ingenix methodologies based on the facts alleged regarding that plaintiff so those claims are back in the case. Fact discovery is complete. The plaintiffs filed a motion for class certification in November 2013. The plaintiffs seek the following classes: (1) a subscriber ERISA class as to OON claims processed using the Ingenix database as the pricing methodology; (2) a physician provider class as to OON claims processed using Ingenix; (3) a non-physician provider class as to OON claims processed using Ingenix; (4) a provider ERISA class as to OON claims processed using non-Ingenix pricing methodologies; (5) a California subscriber breach of contract/unfair competition class; and (6) a subscriber breach of implied covenant class for all WellPoint states except California. We deposed all of the plaintiffs’ class certification experts. In March 2014, we filed a response in opposition to class certification, along with a supporting expert report, and motions to exclude the plaintiffs’ class certification experts. A hearing on our motions to exclude plaintiffs’ class certification experts is set for June 2014. Earlier in the case, in 2009, we filed a motion in the United States District Court for the Southern District of Florida, or the Florida Court, to enjoin the claims brought by the medical doctors and doctors of osteopathy and certain medical associations based on prior litigation releases, which was granted in 2011. The Florida Court ordered the plaintiffs to dismiss their claims that are barred by the release. The plaintiffs then filed a petition for declaratory judgment asking the court to find that these claims are not barred by the releases from the prior litigation. We filed a motion to dismiss the declaratory judgment action, which was granted. The plaintiffs appealed the dismissal of the declaratory judgment to the United States Court of Appeals for the Eleventh Circuit, but the dismissal was upheld. The enjoined physicians have not yet dismissed their claims. The Florida Court found the enjoined physicians in contempt and sanctioned them in July 2012. The barred physicians are paying the sanctions and have appealed the Florida Court’s sanctions order to the United States Court of Appeals for the Eleventh Circuit. Oral argument on that appeal occurred in October 2013. We intend to vigorously defend these suits; however, their ultimate outcome cannot be presently determined.
	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, for all of those proceedings is from $0.0 to approximately $250.0 at March 31, 2014. 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.
	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 health care 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 settlements 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.
	The National Organization of Life & Health Insurance Guaranty Associations, or NOLHGA, is a voluntary organization consisting of the state life and health insurance guaranty associations located throughout the U.S. State life and health insurance guaranty associations, working together with NOLHGA, provide a safety net for their state’s policyholders, ensuring that they continue to receive coverage even if their insurer is declared insolvent. We are aware that the Pennsylvania Insurance Commissioner, or Insurance Commissioner, has placed Penn Treaty Network America Insurance Company and its subsidiary American Network Insurance Company, or collectively Penn Treaty, in rehabilitation, an intermediate action before insolvency. The state court denied the Insurance Commissioner’s petition for the liquidation of Penn Treaty and ordered the Insurance Commissioner to file an updated plan of rehabilitation, which proposed plan was filed on April 30, 2013. The state court has ordered a hearing on the proposed plan for which a date has not yet been set. The Insurance Commissioner has filed a Notice of Appeal asking the Pennsylvania Supreme Court to reverse the order denying the liquidation petition. The Supreme Court has probable jurisdiction over the appeal and issued a schedule for filing briefs. In the event rehabilitation of Penn Treaty is unsuccessful and Penn Treaty is declared insolvent and placed in liquidation, we and other insurers may be required to pay a portion of their policyholder claims through state guaranty association assessments in future periods. Given the uncertainty around whether Penn Treaty will ultimately be declared insolvent and, if so, the amount of the insolvency, the amount and timing of any associated future guaranty fund assessments and the availability and amount of any potential premium tax and other offsets, we currently cannot estimate our net exposure, if any, to this potential insolvency. We will continue to monitor the situation and may record a liability and expense in future reporting periods, which could be material to our cash flows and results of operations.
	Contractual Obligations and Commitments
	We are a party to an agreement with Express Scripts, Inc., or Express Scripts, to provide pharmacy benefit management, or PBM, services for our plans, excluding Amerigroup and certain self-insured members, which have exclusive agreements with different PBM services providers; provided however that Amerigroup will be transitioning to the Express Scripts agreement during 2014. The initial term of this agreement expires on December 31, 2019. Under this agreement, Express Scripts is the exclusive provider of certain specified PBM services, such as pharmacy network management, home delivery, pharmacy customer service, claims processing, rebate management, drug utilization and specialty pharmaceutical management services. Accordingly, the agreement contains certain financial and operational requirements obligating both Express Scripts and us. Express Scripts’ primary obligations relate to the performance of such services and meeting certain pricing guarantees and performance standards. Our primary obligations relate to oversight, provision of data, payment for services and certain minimum volume requirements. The failure by either party to meet the respective requirements could potentially serve as a basis for financial penalties or early termination of the contract. We believe we have appropriately recognized all rights and obligations under this contract at March 31, 2014.
	During the first quarter of 2010, we entered into an agreement with International Business Machines Corporation to provide information technology infrastructure services. This new agreement supersedes certain prior agreements and also includes provisions for additional services. Our remaining commitment under this agreement at March 31, 2014 was $214.7 through March 31, 2015. We have the ability to terminate this agreement upon the occurrence of certain events, subject to early termination fees.
	On March 31, 2009, we entered into an agreement with Affiliated Computer Services, Inc. to provide certain print and mailroom services that were previously performed in-house. Our remaining commitment under this agreement at March 31, 2014 was $125.7 through March 31, 2016. We have the ability to terminate this agreement upon the occurrence of certain events, subject to early termination fees.

Capital_Stock

Capital Stock	3 Months Ended
	Mar. 31, 2014
Capital [Abstract]	'
Capital Stock	'
	Capital Stock
	Use of Capital – Dividends and Stock Repurchase Program
	We regularly review the appropriate use of capital, including 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 are at the discretion of our Board of Directors and depend 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 three months ended March 31, 2014 and 2013 is as follows:
	Declaration Date		Record Date	Payment Date		Cash	Total
						Dividend
						per Share
	Three Months Ended March 31, 2014
	January 28, 2014		March 10, 2014	March 25, 2014		$0.44	$123.40
	Three Months Ended March 31, 2013
	February 20, 2013		March 8, 2013	March 25, 2013		$0.38	$113.40
	Under our Board of Directors’ authorization, we maintain a 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 for the period April 1, 2014 through April 15, 2014 (subsequent to March 31, 2014) and for the three months ended March 31, 2014 and 2013 is as follows:
		April 1, 2014			Three Months Ended
		Through			March 31
		April 15, 2014			2014			2013
	Shares repurchased	2.3			14.3			5.5
	Average price per share	$	98.03		$	88.14		$	62.41
	Aggregate cost	$	220.8		$	1,262.80		$	340.2
	Authorization remaining at the end of each period	$	2,207.40		$	2,428.20		$	1,496.60
	Under the common stock repurchase program authorized by our Board of Directors, on February 4, 2014, we entered into an accelerated share repurchase agreement with a counterparty. The agreement provided for the repurchase of a number of our shares, equal to $600.0, as determined by the volume weighted-average price of our shares during the term of the agreement. During the three months ended March 31, 2014 we repurchased 6.6 shares under the agreement. The shares repurchased under the agreement are included in the amount disclosed above as shares repurchased during the three months ended March 31, 2014.
	Stock Incentive Plans
	A summary of stock option activity for the three months ended March 31, 2014 is as follows:
		Number of		Weighted-			Weighted-		Aggregate
		Shares		Average			Average		Intrinsic
				Option Price			Remaining		Value
				per Share			Contractual
							Life (Years)
	Outstanding at January 1, 2014	10		$	65.38
	Granted	1.7		89.44
	Exercised	(2.0	)	66.39
	Forfeited or expired	(0.1	)	62.71
	Outstanding at March 31, 2014	9.6		69.46			3.9		$	289.6
	Exercisable at March 31, 2014	6.3		65.72			2.6		$	212.6
	A summary of the status of nonvested restricted stock activity, including restricted stock units, for the three months ended March 31, 2014 is as follows:
		Restricted		Weighted-
		Stock Shares		Average
		and Units		Grant Date
				Fair Value
				per Share
	Nonvested at January 1, 2014	4.2		$	63.83
	Granted	1.3		89.43
	Vested	(1.5	)	64.15
	Forfeited	(0.3	)	63.33
	Nonvested at March 31, 2014	3.7		72.51
	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 15, “Capital Stock,” to our audited consolidated financial statements as of and for the year ended December 31, 2013 included in our 2013 Annual Report on Form 10-K.
	The following weighted-average assumptions were used to estimate the fair values of options granted during the three months ended March 31, 2014 and 2013:
		2014		2013
	Risk-free interest rate	2.16	%	1.25	%
	Volatility factor	35	%	35	%
	Quarterly dividend yield	0.5	%	0.6	%
	Weighted-average expected life (years)	3.75		4
	The following weighted-average fair values were determined for the three months ended March 31, 2014 and 2013:
		2014			2013
	Options granted during the period	$	22.2		$	14.51
	Restricted stock awards granted during the period	89.43			61.81

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2014
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]	'
Accumulated Other Comprehensive Income (Loss)	'
	Accumulated Other Comprehensive Income
	A reconciliation of the components of accumulated other comprehensive income at March 31, 2014 and 2013 is as follows:
		2014			2013
	Investments:
	Gross unrealized gains	$	1,156.50		$	1,324.30
	Gross unrealized losses	(161.8		)	(53.1		)
	Net pre-tax unrealized gains	994.7			1,271.20
	Deferred tax liability	(345.4		)	(433.2		)
	Net unrealized gains on investments	649.3			838
	Cash flow hedges:
	Gross unrealized losses	(48.6		)	(53.0		)
	Deferred tax asset	17			18.6
	Net unrealized losses on cash flow hedges	(31.6		)	(34.4		)
	Defined benefit pension plans:
	Deferred net actuarial loss	(426.4		)	(674.8		)
	Deferred prior service credits	8.4			3.7
	Deferred tax asset	167.5			264.4
	Net unrecognized periodic benefit costs for defined benefit pension plans	(250.5		)	(406.7		)
	Postretirement benefit plans:
	Deferred net actuarial loss	(154.7		)	(188.3		)
	Deferred prior service credits	86.2			99.8
	Deferred tax asset	27.4			34.8
	Net unrecognized periodic benefit costs for postretirement benefit plans	(41.1		)	(53.7		)
	Foreign currency translation adjustments:
	Gross unrealized gains (losses)	2			(1.1		)
	Deferred tax (liability) asset	(0.7		)	0.4
	Net unrealized gains (losses) on foreign currency translation adjustments	1.3			(0.7		)
	Accumulated other comprehensive income	$	327.4		$	342.5
	Other comprehensive income (loss) reclassification adjustments for the three months ended March 31, 2014 and 2013 are as follows:
		2014			2013
	Investments:
	Net holding gain on investment securities arising during the period, net of tax expense of ($67.5) and ($2.4), respectively	$	120.2		$	29.7
	Reclassification adjustment for net realized gain on investment securities, net of tax expense of ($10.8) and ($2.6), respectively	20.1			4.8
	Total reclassification adjustment on investments	140.3			34.5
	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 ($0.3) and ($1.2), respectively	0.5			2.2
	Cash flow hedges:
	Holding gain, net of tax expense of ($0.4) and ($0.4), respectively	0.7			0.7
	Other:
	Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, net of tax expense of ($1.9) and ($4.4), respectively	2.9			6.8
	Foreign currency translation adjustment, net of tax benefit of $0.0 and $0.5, respectively	(0.2		)	(0.8		)
	Net gain recognized in other comprehensive income, net of tax expense of ($80.9) and ($10.5), respectively	$	144.2		$	43.4

Earnings_Per_Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	Earnings per Share
	The denominator for basic and diluted earnings per share for the three months ended March 31, 2014 and 2013 is as follows:
		Three Months Ended
		March 31
		2014	2013
	Denominator for basic earnings per share – weighted-average shares	284.9	303.2
	Effect of dilutive securities – employee stock options, non-vested restricted stock awards and convertible debentures	7.7	2.7
	Denominator for diluted earnings per share	292.6	305.9
	During the three months ended March 31, 2014 and 2013, weighted-average shares related to certain stock options of 0.6 and 11.5, respectively, were excluded from the denominator for diluted earnings per share because the stock options were anti-dilutive.
	During the three months ended March 31, 2014, we issued approximately 1.3 restricted stock units under our stock incentive plans, 0.7 of which vesting is contingent upon us meeting specified annual operating gain targets for 2014. The contingent restricted stock units have been excluded from the denominator for diluted earnings per share and will be included only if and when the contingency is met.

Segment_Information

Segment Information	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Segment Information	'
	Segment Information
	The results of our operations are described through three reportable segments: Commercial and Specialty Business, Government Business and Other, as further described in Note 20, “Segment Information,” to our audited consolidated financial statements as of and for the year ended December 31, 2013 included in our 2013 Annual Report on Form 10-K.
	Effective January 1, 2014, our Employer Group Medicare Advantage members are being reported within Local Group and National Accounts in our Commercial and Specialty Business segment and prior period segment amounts have been reclassified to conform to the new presentation. These members were previously reported with our Medicare membership within our Government Business segment. The Employer Group Medicare Advantage members are retired members who have selected a Medicare Advantage product through our Local Group and National Accounts. Financial data by reportable segment for the three months ended March 31, 2014 and 2013 is as follows (amounts reported for prior periods have been reclassified to conform to our new segment reporting structure):
		Commercial				Government				Other			Total
		and Specialty				Business
		Business
	Three Months Ended March 31, 2014:
	Operating revenue	$	9,697.50			$	7,941.30			$	6		$	17,644.80
	Operating gain (loss)	886.1				239.6				(7.0		)	1,118.70
	Three Months Ended March 31, 2013:
	Operating revenue	$	9,859.40			$	7,569.40			$	6.3		$	17,435.10
	Operating gain (loss)	1,262.10				102.6				(7.4		)	1,357.30
	A reconciliation of reportable segment operating revenues to the amounts of total revenues included in the consolidated statements of income for the three months ended March 31, 2014 and 2013 is as follows:
			Three Months Ended
			March 31
			2014				2013
	Reportable segments operating revenues		$	17,644.80			$	17,435.10
	Net investment income		183.7				162
	Net realized gains on investments		41.7				16.8
	Other-than-temporary impairment losses recognized in income		(10.8		)		(37.9		)
	Total revenues		$	17,859.40			$	17,576.00
	A reconciliation of reportable segment operating gain to income from continuing operations before income taxes included in the consolidated statements of income for the three months ended March 31, 2014 and 2013 is as follows:
		Three Months Ended
		March 31
		2014				2013
	Reportable segments operating gain	$	1,118.70			$	1,357.30
	Net investment income	183.7				162
	Net realized gains on investments	41.7				16.8
	Other-than-temporary impairment losses recognized in income	(10.8		)		(37.9		)
	Interest expense	(146.2		)		(153.5		)
	Amortization of other intangible assets	(54.0		)		(62.2		)
	Loss on extinguishment of debt	(3.0		)		—
	Income from continuing operations before income tax expense	$	1,130.10			$	1,282.50

Recovered_Sheet1

Basis of Presentation and Signficant Accounting Policies	3 Months Ended
	Mar. 31, 2014
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 2013 Annual Report on Form 10-K, unless the information contained in those disclosures materially changed or is required by GAAP. Unless otherwise specified, all financial information presented in the accompanying consolidated financial statements and in the notes to consolidated financial statements relates only to our continuing operations, other than cash flows presented on the consolidated statements of cash flows. 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 months ended March 31, 2014 and 2013 have been recorded. The results of operations for the three months ended March 31, 2014 are not necessarily indicative of the results that may be expected for the full year ending December 31, 2014. These unaudited consolidated financial statements should be read in conjunction with our audited consolidated financial statements for the year ended December 31, 2013 included in our 2013 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.
Revenue Recognition	'
	Revenue Recognition: Premiums for fully-insured contracts are recognized as revenue over the period insurance coverage is provided, net of amounts recognized for minimum medical loss ratio rebates, if applicable, and the risk adjustment, reinsurance, and risk corridor premium stabilization programs of the Patient Protection and Affordable Care Act and the Health Care and Education Reconciliation Act of 2010. Premiums related to the unexpired contractual coverage periods are reflected in the accompanying consolidated balance sheets as unearned income. Premiums include revenue from retrospectively rated contracts where revenue is based on the estimated ultimate loss experience of the contract. Premium revenue includes an adjustment for retrospectively rated refunds based on an estimate of incurred claims. Premium rates for certain lines of business are subject to approval by the Department of Insurance of each respective state.
	Administrative fees 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. In addition, administrative fees include amounts received for the administration of Medicare or certain other government programs. Under our self-funded arrangements, revenue is recognized as administrative services are performed. All benefit payments under these programs are excluded from benefit expense.
Adoption of New Accounting Pronouncements	'
	Adoption of New Accounting Pronouncement: Effective January 1, 2014, we adopted the provisions of Accounting Standards Update No. 2011-06, Other Expenses (Topic 720): Fees Paid to the Federal Government by Health Insurers (a consensus of the FASB Emerging Issues Task Force), or ASU 2011-06. The Patient Protection and Affordable Care Act and the Health Care and Education Reconciliation Act of 2010, or collectively, Health Care Reform, imposes a mandatory annual Health Insurance Provider Fee, or HIP Fee, on health insurers that write certain types of health insurance on U.S. risks. The annual HIP Fee is allocated to health insurers based on the ratio of the amount of an insurer's net premium revenues written during the preceding calendar year to the amount of health insurance for all U.S. health risk for those certain lines of business written during the preceding calendar year. This fee is non-deductible for federal income tax purposes. The total amount to be collected from allocations to health insurers in 2014 is $8,000.0, and we estimate our portion of the fee for 2014 to be approximately $920.0. ASU 2011-06 addresses how this fee should be recognized and classified in the financial statements of health insurers. In accordance with ASU 2011-06, we recorded our estimated liability for the fee in full at the beginning of the year with a corresponding deferred cost that is being amortized to expense on a straight-line basis, and we recognized $230.0 as general and administrative expense related to the fee for the three months ended March 31, 2014. The final calculation and payment of the fee will occur in the third quarter of 2014.
Reclassifications	'
	Reclassifications: Certain prior period amounts have been reclassified to conform to the current period presentation.

Investments_Tables

Investments (Tables)	3 Months Ended
	Mar. 31, 2014
Investments [Abstract]	'
Current and Long-Term Investments, Available-For-Sale	'
	A summary of current and long-term investments, available-for-sale, at March 31, 2014 and December 31, 2013 is as follows:
																				Non-Credit
																				Component of
																				Other-Than-
																				Temporary
																				Impairments
		Cost or			Gross			Gross Unrealized Losses								Estimated				Recognized in
		Amortized			Unrealized											Fair Value				AOCI
		Cost			Gains			Less than				12 Months
								12 Months				or Greater
	March 31, 2014:
	Fixed maturity securities:
	United States Government securities	$	460.2		$	2.7		$	(1.3	)		$	—			$	461.6			$	—
	Government sponsored securities	168.6			0.6			(0.5		)		(0.5		)		168.2				—
	States, municipalities and political subdivisions, tax-exempt	5,801.90			244.4			(33.3		)		(9.5		)		6,003.50				—
	Corporate securities	8,338.40			232.4			(54.8		)		(14.1		)		8,501.90				—
	Options embedded in convertible securities	97.6			—			—				—				97.6				—
	Residential mortgage-backed securities	2,160.00			53.9			(26.8		)		(5.5		)		2,181.60				—
	Commercial mortgage-backed securities	509.4			11.1			(1.1		)		(0.2		)		519.2				—
	Other debt securities	569.3			7.1			(2.8		)		(0.8		)		572.8				—
	Total fixed maturity securities	18,105.40			552.2			(120.6		)		(30.6		)		18,506.40				$	—
	Equity securities	1,400.80			604.3			(10.6		)		—				1,994.50
	Total investments, available-for-sale	$	19,506.20		$	1,156.50		$	(131.2	)		$	(30.6	)		$	20,500.90
	December 31, 2013:
	Fixed maturity securities:
	United States Government securities	$	300.8		$	2.5		$	(3.4	)		$	—			$	299.9			$	—
	Government sponsored securities	174.4			0.4			(1.3		)		—				173.5				—
	States, municipalities and political subdivisions, tax-exempt	5,899.50			202.9			(90.1		)		(9.6		)		6,002.70				(0.6		)
	Corporate securities	7,614.10			205.2			(95.2		)		(15.5		)		7,708.60				(0.1		)
	Options embedded in convertible securities	89.2			—			—				—				89.2				—
	Residential mortgage-backed securities	2,269.40			48			(41.4		)		(7.1		)		2,268.90				—
	Commercial mortgage-backed securities	479			10.5			(2.6		)		(0.3		)		486.6				—
	Other debt securities	456.2			5.8			(2.5		)		(0.8		)		458.7				(0.1		)
	Total fixed maturity securities	17,282.60			475.3			(236.5		)		(33.3		)		17,488.10				$	(0.8	)
	Equity securities	1,195.90			578.9			(8.0		)		—				1,766.80
	Total investments, available-for-sale	$	18,478.50		$	1,054.20		$	(244.5	)		$	(33.3	)		$	19,254.90
Aggregate Fair Value and Gross Unrealized Loss of Fixed Maturity Securities and Equity Securities in an Unrealized Loss Position	'
	The following tables summarize for fixed maturity securities and equity securities in an unrealized loss position at March 31, 2014 and December 31, 2013, the aggregate fair value and gross unrealized loss by length of time those securities have been continuously in an unrealized loss position:
		Less than 12 Months									12 Months or Greater
	(Securities are whole amounts)	Number of		Estimated			Gross				Number of			Estimated				Gross
		Securities		Fair Value			Unrealized				Securities			Fair Value				Unrealized
							Loss											Loss
	March 31, 2014:
	Fixed maturity securities:
	United States Government securities	26		$	300.2		$	(1.3	)		—			$	—			$	—
	Government sponsored securities	15		28.8			(0.5		)		5			17				(0.5		)
	States, municipalities and political subdivisions, tax-exempt	496		1,351.00			(33.3		)		73			168				(9.5		)
	Corporate securities	1,215		2,198.90			(54.8		)		102			127.9				(14.1		)
	Residential mortgage-backed securities	490		985.9			(26.8		)		74			115.1				(5.5		)
	Commercial mortgage-backed securities	37		112.4			(1.1		)		4			4.8				(0.2		)
	Other debt securities	61		177.7			(2.8		)		19			17.1				(0.8		)
	Total fixed maturity securities	2,340		5,154.90			(120.6		)		277			449.9				(30.6		)
	Equity securities	505		131.8			(10.6		)		—			—				—
	Total fixed maturity and equity securities	2,845		$	5,286.70		$	(131.2	)		277			$	449.9			$	(30.6	)
	December 31, 2013:
	Fixed maturity securities:
	United States Government securities	27		$	179.2		$	(3.4	)		—			$	—			$	—
	Government sponsored securities	22		73.4			(1.3		)		—			—				—
	States, municipalities and political subdivisions, tax-exempt	806		2,070.90			(90.1		)		42			82.4				(9.6		)
	Corporate securities	1,448		2,586.60			(95.2		)		107			81.3				(15.5		)
	Residential mortgage-backed securities	605		1,243.00			(41.4		)		80			116.2				(7.1		)
	Commercial mortgage-backed securities	52		177.7			(2.6		)		4			5.6				(0.3		)
	Other debt securities	65		185.3			(2.5		)		17			16.2				(0.8		)
	Total fixed maturity securities	3,025		6,516.10			(236.5		)		250			301.7				(33.3		)
	Equity securities	426		120.8			(8.0		)		—			—				—
	Total fixed maturity and equity securities	3,451		$	6,636.90		$	(244.5	)		250			$	301.7			$	(33.3	)
Amortized Cost and Fair Value of Fixed Maturity Securities, By Contractual Maturity	'
	The amortized cost and fair value of fixed maturity securities at March 31, 2014, 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			Estimated
		Cost			Fair Value
	Due in one year or less	$	444		$	447.4
	Due after one year through five years	4,580.90			4,714.90
	Due after five years through ten years	5,077.60			5,230.70
	Due after ten years	5,333.50			5,412.60
	Mortgage-backed securities	2,669.40			2,700.80
	Total available-for-sale fixed maturity securities	$	18,105.40		$	18,506.40
Proceeds and Realized Gains Losses from Investments	'
	Proceeds from fixed maturity securities, equity securities and other invested assets and the related gross realized gains and gross realized losses for the three months ended March 31, 2014 and 2013 are as follows:
		Three Months Ended
		March 31
		2014			2013
	Proceeds	$	2,401.40		$	3,117.60
	Gross realized gains	82.9			107
	Gross realized losses	41.2			90.2

Fair_Value_Tables

Fair Value (Tables)	3 Months Ended
	Mar. 31, 2014
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [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 March 31, 2014 and December 31, 2013 is as follows:
		Level I			Level II			Level III			Total
	March 31, 2014:
	Assets:
	Cash equivalents	$	612.4		$	—		$	—		$	612.4
	Investments available-for-sale:
	Fixed maturity securities:
	United States Government securities	461.6			—			—			461.6
	Government sponsored securities	—			168.2			—			168.2
	States, municipalities and political subdivisions, tax-exempt	—			6,003.50			—			6,003.50
	Corporate securities	12			8,375.90			114			8,501.90
	Options embedded in convertible debt securities	—			97.6			—			97.6
	Residential mortgage-backed securities	—			2,181.60			—			2,181.60
	Commercial mortgage-backed securities	—			516.1			3.1			519.2
	Other debt securities	71.3			486.7			14.8			572.8
	Total fixed maturity securities	544.9			17,829.60			131.9			18,506.40
	Equity securities	1,766.20			185.1			43.2			1,994.50
	Other invested assets, current	25.9			—			—			25.9
	Securities lending collateral	532			793			—			1,325.00
	Derivatives excluding embedded options (reported with other assets)	—			29			—			29
	Long-term receivable (reported with other assets)	—			—			21.6			21.6
	Total assets	$	3,481.40		$	18,836.70		$	196.7		$	22,514.80
	Liabilities:
	Derivatives excluding embedded options (reported with other liabilities)	$	—		$	(20.9	)	$	—		$	(20.9	)
	Total liabilities	$	—		$	(20.9	)	$	—		$	(20.9	)
	December 31, 2013:
	Assets:
	Cash equivalents	$	632.3		$	—		$	—		$	632.3
	Investments available-for-sale:
	Fixed maturity securities:
	United States Government securities	299.9			—			—			299.9
	Government sponsored securities	—			173.5			—			173.5
	States, municipalities and political subdivisions, tax-exempt	—			6,002.70			—			6,002.70
	Corporate securities	—			7,593.40			115.2			7,708.60
	Options embedded in convertible securities	—			89.2			—			89.2
	Residential mortgage-backed securities	—			2,268.90			—			2,268.90
	Commercial mortgage-backed securities	—			480.1			6.5			486.6
	Other debt securities	35.6			408.3			14.8			458.7
	Total fixed maturity securities	335.5			17,016.10			136.5			17,488.10
	Equity securities	1,475.70			249.7			41.4			1,766.80
	Other invested assets, current	16.3			—			—			16.3
	Securities lending collateral	408.5			561.3			—			969.8
	Derivatives excluding embedded options (reported with other assets)	—			58.4			—			58.4
	Total assets	$	2,868.30		$	17,885.50		$	177.9		$	20,931.70
	Liabilities:
	Derivatives excluding embedded options (reported with other liabilities)	$	—		$	(20.7	)	$	—		$	(20.7	)
	Total liabilities	$	—		$	(20.7	)	$	—		$	(20.7	)
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 March 31, 2014 and 2013 is as follows:
		Corporate			Residential			Commercial			Other Debt			Equity			Long-term Receivable		Total
		Securities			Mortgage-			Mortgage-			Securities			Securities
					backed			backed
					Securities			Securities
	Three Months Ended March 31, 2014:
	Beginning balance at January 1, 2014	$	115.2		$	—		$	6.5		$	14.8		$	41.4		$	—	$	177.9
	Total gains (losses):
	Recognized in net income	(3.3		)	—			—			—			(0.3		)	21.6		18
	Recognized in accumulated other comprehensive income	3.1			—			—			0.2			(5.8		)	—		(2.5		)
	Purchases	9.3			—			—			—			9			—		18.3
	Sales	(1.7		)	—			—			—			(1.1		)	—		(2.8		)
	Settlements	(2.1		)	—			(3.4		)	(0.2		)	—			—		(5.7		)
	Transfers into Level III	—			—			—			—			—			—		—
	Transfers out of Level III	(6.5		)	—			—			—			—			—		(6.5		)
	Ending balance at March 31, 2014	$	114		$	—		$	3.1		$	14.8		$	43.2		$	21.6	$	196.7
	Change in unrealized losses included in net income related to assets still held for the three months ended March 31, 2014	$	(4.0	)	$	—		$	—		$	—		$	(0.3	)	$	—	$	(4.3	)
	Three Months Ended March 31, 2013:
	Beginning balance at January 1, 2013	$	121.1		$	4.3		$	—		$	3.9		$	26.2		$	—	$	155.5
	Total gains (losses):
	Recognized in net income	0.3			—			—			—			0.6			—		0.9
	Recognized in accumulated other comprehensive income	(0.6		)	—			—			0.2			(0.9		)	—		(1.3		)
	Purchases	9.6			—			—			—			0.4			—		10
	Sales	—			—			—			—			(2.5		)	—		(2.5		)
	Settlements	(9.1		)	(1.6		)	—			(0.2		)	—			—		(10.9		)
	Transfers into Level III	—			13.1			—			—			—			—		13.1
	Transfers out of Level III	—			(2.9		)	—			—			—			—		(2.9		)
	Ending balance at March 31, 2013	$	121.3		$	12.9		$	—		$	3.9		$	23.8		$	—	$	161.9
	Change in unrealized losses included in net income related to assets still held for the three months ended March 31, 2013	$	—		$	—		$	—		$	—		$	(1.4	)	$	—	$	(1.4	)
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 March 31, 2014 and December 31, 2013 are as follows:
		Carrying			Fair Value
		Value			Level I			Level II			Level III			Total
	March 31, 2014
	Assets:
	Other invested assets, long-term	$	1,593.80		$	—		$	—		$	1,593.80		$	1,593.80
	Liabilities:
	Debt:
	Short-term borrowings	590			—			590			—			590
	Commercial paper	758.6			—			758.6			—			758.6
	Notes	12,724.10			—			13,285.10			—			13,285.10
	Convertible debentures	968.1			—			2,192.80			—			2,192.80
	December 31, 2013
	Assets:
	Other invested assets, long-term	$	1,542.60		$	—		$	—		$	1,542.60		$	1,542.60
	Liabilities:
	Debt:
	Short-term borrowings	400			—			400			—			400
	Commercial paper	379.2			—			379.2			—			379.2
	Notes	12,746.40			—			13,014.30			—			13,014.30
	Convertible debentures	966			—			2,030.60			—			2,030.60

Retirement_Benefits_Tables

Retirement Benefits (Tables)	3 Months Ended
	Mar. 31, 2014
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]	'
Components of Net Periodic Benefit Costs	'
	The components of net periodic (credit) benefit cost included in the consolidated statements of income for the three months ended March 31, 2014 and 2013 are as follows:
		Pension Benefits						Other Benefits
		2014			2013			2014			2013
	Service cost	$	3.3		$	3.6		$	0.8		$	1.6
	Interest cost	18.5			16.7			6.6			5.6
	Expected return on assets	(34.4		)	(33.3		)	(5.8		)	(5.5		)
	Recognized actuarial loss	5.3			8.6			2.3			2.8
	Settlement loss	1.1			3.4			—			—
	Amortization of prior service credit	(0.2		)	(0.2		)	(3.6		)	(3.3		)
	Net periodic (credit) benefit cost	$	(6.4	)	$	(1.2	)	$	0.3		$	1.2

Debt_Tables

Debt (Tables)	3 Months Ended
	Mar. 31, 2014
Debt Instruments [Abstract]	'
Convertible Debenture Terms	'
	The following table summarizes at March 31, 2014 the related balances, conversion rate and conversion price of the Debentures:
	Outstanding principal amount	$	1,500.00
	Unamortized debt discount	531.9
	Net debt carrying amount	968.1
	Equity component carrying amount	543.6
	Conversion rate (shares of common stock per $1,000 of principal amount)	13.3135
	Effective conversion price (per $1,000 of principal amount)	$	75.1113

Capital_Stock_Tables

Capital Stock (Tables)	3 Months Ended
	Mar. 31, 2014
Capital [Abstract]	'
Summary of Cash Dividend Activity	'
	A summary of the cash dividend activity for the three months ended March 31, 2014 and 2013 is as follows:
	Declaration Date		Record Date	Payment Date		Cash	Total
						Dividend
						per Share
	Three Months Ended March 31, 2014
	January 28, 2014		March 10, 2014	March 25, 2014		$0.44	$123.40
	Three Months Ended March 31, 2013
	February 20, 2013		March 8, 2013	March 25, 2013		$0.38	$113.40
Summary of Share Repurchases	'
	A summary of common stock repurchases for the period April 1, 2014 through April 15, 2014 (subsequent to March 31, 2014) and for the three months ended March 31, 2014 and 2013 is as follows:
		April 1, 2014			Three Months Ended
		Through			March 31
		April 15, 2014			2014			2013
	Shares repurchased	2.3			14.3			5.5
	Average price per share	$	98.03		$	88.14		$	62.41
	Aggregate cost	$	220.8		$	1,262.80		$	340.2
	Authorization remaining at the end of each period	$	2,207.40		$	2,428.20		$	1,496.60
Summary of Stock Option Activity	'
	A summary of stock option activity for the three months ended March 31, 2014 is as follows:
		Number of		Weighted-			Weighted-		Aggregate
		Shares		Average			Average		Intrinsic
				Option Price			Remaining		Value
				per Share			Contractual
							Life (Years)
	Outstanding at January 1, 2014	10		$	65.38
	Granted	1.7		89.44
	Exercised	(2.0	)	66.39
	Forfeited or expired	(0.1	)	62.71
	Outstanding at March 31, 2014	9.6		69.46			3.9		$	289.6
	Exercisable at March 31, 2014	6.3		65.72			2.6		$	212.6
Summary of Nonvested Restricted Stock Activity Including Restricted Stock Units	'
	A summary of the status of nonvested restricted stock activity, including restricted stock units, for the three months ended March 31, 2014 is as follows:
		Restricted		Weighted-
		Stock Shares		Average
		and Units		Grant Date
				Fair Value
				per Share
	Nonvested at January 1, 2014	4.2		$	63.83
	Granted	1.3		89.43
	Vested	(1.5	)	64.15
	Forfeited	(0.3	)	63.33
	Nonvested at March 31, 2014	3.7		72.51
Schedule of Fair Values of Options Granted During The Period Estimated Using Weighted-Average Assumptions	'
	The following weighted-average assumptions were used to estimate the fair values of options granted during the three months ended March 31, 2014 and 2013:
		2014		2013
	Risk-free interest rate	2.16	%	1.25	%
	Volatility factor	35	%	35	%
	Quarterly dividend yield	0.5	%	0.6	%
	Weighted-average expected life (years)	3.75		4
Schedule of Weighted-Average Fair Values Determined For The Periods	'
	The following weighted-average fair values were determined for the three months ended March 31, 2014 and 2013:
		2014			2013
	Options granted during the period	$	22.2		$	14.51
	Restricted stock awards granted during the period	89.43			61.81

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Loss)(Tables)	3 Months Ended
	Mar. 31, 2014
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]	'
Components Of Accumulated Other Comprehensive Income (Loss)	'
	A reconciliation of the components of accumulated other comprehensive income at March 31, 2014 and 2013 is as follows:
		2014			2013
	Investments:
	Gross unrealized gains	$	1,156.50		$	1,324.30
	Gross unrealized losses	(161.8		)	(53.1		)
	Net pre-tax unrealized gains	994.7			1,271.20
	Deferred tax liability	(345.4		)	(433.2		)
	Net unrealized gains on investments	649.3			838
	Cash flow hedges:
	Gross unrealized losses	(48.6		)	(53.0		)
	Deferred tax asset	17			18.6
	Net unrealized losses on cash flow hedges	(31.6		)	(34.4		)
	Defined benefit pension plans:
	Deferred net actuarial loss	(426.4		)	(674.8		)
	Deferred prior service credits	8.4			3.7
	Deferred tax asset	167.5			264.4
	Net unrecognized periodic benefit costs for defined benefit pension plans	(250.5		)	(406.7		)
	Postretirement benefit plans:
	Deferred net actuarial loss	(154.7		)	(188.3		)
	Deferred prior service credits	86.2			99.8
	Deferred tax asset	27.4			34.8
	Net unrecognized periodic benefit costs for postretirement benefit plans	(41.1		)	(53.7		)
	Foreign currency translation adjustments:
	Gross unrealized gains (losses)	2			(1.1		)
	Deferred tax (liability) asset	(0.7		)	0.4
	Net unrealized gains (losses) on foreign currency translation adjustments	1.3			(0.7		)
	Accumulated other comprehensive income	$	327.4		$	342.5
Other Comprehensive Income (Loss) Reclassification Adjustments	'
	Other comprehensive income (loss) reclassification adjustments for the three months ended March 31, 2014 and 2013 are as follows:
		2014			2013
	Investments:
	Net holding gain on investment securities arising during the period, net of tax expense of ($67.5) and ($2.4), respectively	$	120.2		$	29.7
	Reclassification adjustment for net realized gain on investment securities, net of tax expense of ($10.8) and ($2.6), respectively	20.1			4.8
	Total reclassification adjustment on investments	140.3			34.5
	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 ($0.3) and ($1.2), respectively	0.5			2.2
	Cash flow hedges:
	Holding gain, net of tax expense of ($0.4) and ($0.4), respectively	0.7			0.7
	Other:
	Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, net of tax expense of ($1.9) and ($4.4), respectively	2.9			6.8
	Foreign currency translation adjustment, net of tax benefit of $0.0 and $0.5, respectively	(0.2		)	(0.8		)
	Net gain recognized in other comprehensive income, net of tax expense of ($80.9) and ($10.5), respectively	$	144.2		$	43.4

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Denominator for Basic and Diluted Earnings Per Share	'
	The denominator for basic and diluted earnings per share for the three months ended March 31, 2014 and 2013 is as follows:
		Three Months Ended
		March 31
		2014	2013
	Denominator for basic earnings per share – weighted-average shares	284.9	303.2
	Effect of dilutive securities – employee stock options, non-vested restricted stock awards and convertible debentures	7.7	2.7
	Denominator for diluted earnings per share	292.6	305.9

Segment_Information_Tables

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Financial Data By Reportable Segment	'
	Financial data by reportable segment for the three months ended March 31, 2014 and 2013 is as follows (amounts reported for prior periods have been reclassified to conform to our new segment reporting structure):
		Commercial				Government				Other			Total
		and Specialty				Business
		Business
	Three Months Ended March 31, 2014:
	Operating revenue	$	9,697.50			$	7,941.30			$	6		$	17,644.80
	Operating gain (loss)	886.1				239.6				(7.0		)	1,118.70
	Three Months Ended March 31, 2013:
	Operating revenue	$	9,859.40			$	7,569.40			$	6.3		$	17,435.10
	Operating gain (loss)	1,262.10				102.6				(7.4		)	1,357.30
Reconciliation Of Reportable Segments Operating Revenues To Total Revenues Reported In The Consolidated Statements Of Income	'
	A reconciliation of reportable segment operating revenues to the amounts of total revenues included in the consolidated statements of income for the three months ended March 31, 2014 and 2013 is as follows:
			Three Months Ended
			March 31
			2014				2013
	Reportable segments operating revenues		$	17,644.80			$	17,435.10
	Net investment income		183.7				162
	Net realized gains on investments		41.7				16.8
	Other-than-temporary impairment losses recognized in income		(10.8		)		(37.9		)
	Total revenues		$	17,859.40			$	17,576.00
Reconciliation Of Reportable Segments Operating Gain To Income Before Income Tax Expense Included In The Consolidated Statements Of Income	'
	A reconciliation of reportable segment operating gain to income from continuing operations before income taxes included in the consolidated statements of income for the three months ended March 31, 2014 and 2013 is as follows:
		Three Months Ended
		March 31
		2014				2013
	Reportable segments operating gain	$	1,118.70			$	1,357.30
	Net investment income	183.7				162
	Net realized gains on investments	41.7				16.8
	Other-than-temporary impairment losses recognized in income	(10.8		)		(37.9		)
	Interest expense	(146.2		)		(153.5		)
	Amortization of other intangible assets	(54.0		)		(62.2		)
	Loss on extinguishment of debt	(3.0		)		—
	Income from continuing operations before income tax expense	$	1,130.10			$	1,282.50

Organization_Details

Organization (Details)	Mar. 31, 2014
	county
	states
	medical_member
	individuals
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Number of medical membership members	36,900,000
Individuals served	66,800,000
Number of counties in the Kansas City area the Company does not serve	30
Number of counties in the New York City metropolitan area the Company serves as independent licensee	10
Number of states in which the Company is licensed to conduct insurance operations	50

Basis_of_Presentation_and_Sign1

Basis of Presentation and Signficant Accounting Policies Adoption of New Accounting Pronouncement (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014
Adoption of New Accounting Pronouncement [Abstract]	'
Patient Protection Affordable Care Act Health Insurance Provider Fee, annual amount to be collected by the Government through assessments to all health insurers subject to the fee	$8,000
Patient Protection Affordable Care Act Health Insurance Provider Fee, estimated amount	920
Patient Protection Affordable Care Act Health Insurance Provider Fee Expense Recognized	$230

Investments_Current_And_LongTe

Investments (Current And Long-Term Investments, Available-For-Sale) (Details) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Investments [Line Items]	'	'	'
Cost or Amortized Cost	$19,506.20	'	$18,478.50
Gross Unrealized Gains	1,156.50	1,324.30	1,054.20
Gross Unrealized Losses, Less than 12 Months	-131.2	'	-244.5
Gross Unrealized Losses, 12 Months or Greater	-30.6	'	-33.3
Estimated Fair Value	20,500.90	'	19,254.90
Equity Securities [Member]	'	'	'
Investments [Line Items]	'	'	'
Cost or Amortized Cost	1,400.80	'	1,195.90
Gross Unrealized Gains	604.3	'	578.9
Gross Unrealized Losses, Less than 12 Months	-10.6	'	-8
Gross Unrealized Losses, 12 Months or Greater	0	'	0
Estimated Fair Value	1,994.50	'	1,766.80
Fixed Maturities [Member]	'	'	'
Investments [Line Items]	'	'	'
Cost or Amortized Cost	18,105.40	'	17,282.60
Gross Unrealized Gains	552.2	'	475.3
Gross Unrealized Losses, Less than 12 Months	-120.6	'	-236.5
Gross Unrealized Losses, 12 Months or Greater	-30.6	'	-33.3
Estimated Fair Value	18,506.40	'	17,488.10
Non-credit component of other-than-temporary impairments recognized in accumulated other comprehensive income	0	'	-0.8
Fixed Maturities [Member] | United States Government Securities [Member]	'	'	'
Investments [Line Items]	'	'	'
Cost or Amortized Cost	460.2	'	300.8
Gross Unrealized Gains	2.7	'	2.5
Gross Unrealized Losses, Less than 12 Months	-1.3	'	-3.4
Gross Unrealized Losses, 12 Months or Greater	0	'	0
Estimated Fair Value	461.6	'	299.9
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	168.6	'	174.4
Gross Unrealized Gains	0.6	'	0.4
Gross Unrealized Losses, Less than 12 Months	-0.5	'	-1.3
Gross Unrealized Losses, 12 Months or Greater	-0.5	'	0
Estimated Fair Value	168.2	'	173.5
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	5,801.90	'	5,899.50
Gross Unrealized Gains	244.4	'	202.9
Gross Unrealized Losses, Less than 12 Months	-33.3	'	-90.1
Gross Unrealized Losses, 12 Months or Greater	-9.5	'	-9.6
Estimated Fair Value	6,003.50	'	6,002.70
Non-credit component of other-than-temporary impairments recognized in accumulated other comprehensive income	0	'	-0.6
Fixed Maturities [Member] | Corporate Securities [Member]	'	'	'
Investments [Line Items]	'	'	'
Cost or Amortized Cost	8,338.40	'	7,614.10
Gross Unrealized Gains	232.4	'	205.2
Gross Unrealized Losses, Less than 12 Months	-54.8	'	-95.2
Gross Unrealized Losses, 12 Months or Greater	-14.1	'	-15.5
Estimated Fair Value	8,501.90	'	7,708.60
Non-credit component of other-than-temporary impairments recognized in accumulated other comprehensive income	0	'	-0.1
Fixed Maturities [Member] | Options Embedded In Convertible Debt Securities [Member]	'	'	'
Investments [Line Items]	'	'	'
Cost or Amortized Cost	97.6	'	89.2
Gross Unrealized Gains	0	'	0
Gross Unrealized Losses, Less than 12 Months	0	'	0
Gross Unrealized Losses, 12 Months or Greater	0	'	0
Estimated Fair Value	97.6	'	89.2
Non-credit component of other-than-temporary impairments recognized in accumulated other comprehensive income	0	'	0
Fixed Maturities [Member] | Residential Mortgage-Backed Securities [Member]	'	'	'
Investments [Line Items]	'	'	'
Cost or Amortized Cost	2,160	'	2,269.40
Gross Unrealized Gains	53.9	'	48
Gross Unrealized Losses, Less than 12 Months	-26.8	'	-41.4
Gross Unrealized Losses, 12 Months or Greater	-5.5	'	-7.1
Estimated Fair Value	2,181.60	'	2,268.90
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	509.4	'	479
Gross Unrealized Gains	11.1	'	10.5
Gross Unrealized Losses, Less than 12 Months	-1.1	'	-2.6
Gross Unrealized Losses, 12 Months or Greater	-0.2	'	-0.3
Estimated Fair Value	519.2	'	486.6
Non-credit component of other-than-temporary impairments recognized in accumulated other comprehensive income	0	'	0
Fixed Maturities [Member] | Other Debt Securities [Member]	'	'	'
Investments [Line Items]	'	'	'
Cost or Amortized Cost	569.3	'	456.2
Gross Unrealized Gains	7.1	'	5.8
Gross Unrealized Losses, Less than 12 Months	-2.8	'	-2.5
Gross Unrealized Losses, 12 Months or Greater	-0.8	'	-0.8
Estimated Fair Value	572.8	'	458.7
Non-credit component of other-than-temporary impairments recognized in accumulated other comprehensive income	$0	'	($0.10)

Investments_Aggregate_Fair_Val

Investments (Aggregate Fair Value And Gross Unrealized Loss Of Fixed Maturity Securities And Equity Securities In An Unrealized Loss Position) (Details) (USD $)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
	securities	securities
Schedule of Investments [Line Items]	'	'
Number of Securities, Less Than 12 Months	2,845	3,451
Estimated Fair Value, Less Than 12 Months	$5,286.70	$6,636.90
Gross Unrealized Loss, Less Than 12 Months	-131.2	-244.5
Number of Securities, 12 Months or Greater	277	250
Estimated Fair Value, 12 Months or Greater	449.9	301.7
Gross Unrealized Losses, 12 Months or Greater	-30.6	-33.3
Equity Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Number of Securities, Less Than 12 Months	505	426
Estimated Fair Value, Less Than 12 Months	131.8	120.8
Gross Unrealized Loss, Less Than 12 Months	-10.6	-8
Number of Securities, 12 Months or Greater	0	0
Estimated Fair Value, 12 Months or Greater	0	0
Gross Unrealized Losses, 12 Months or Greater	0	0
Fixed Maturities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Number of Securities, Less Than 12 Months	2,340	3,025
Estimated Fair Value, Less Than 12 Months	5,154.90	6,516.10
Gross Unrealized Loss, Less Than 12 Months	-120.6	-236.5
Number of Securities, 12 Months or Greater	277	250
Estimated Fair Value, 12 Months or Greater	449.9	301.7
Gross Unrealized Losses, 12 Months or Greater	-30.6	-33.3
Fixed Maturities [Member] | United States Government Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Number of Securities, Less Than 12 Months	26	27
Estimated Fair Value, Less Than 12 Months	300.2	179.2
Gross Unrealized Loss, Less Than 12 Months	-1.3	-3.4
Number of Securities, 12 Months or Greater	0	0
Estimated Fair Value, 12 Months or Greater	0	0
Gross Unrealized Losses, 12 Months or Greater	0	0
Fixed Maturities [Member] | Government Sponsored Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Number of Securities, Less Than 12 Months	15	22
Estimated Fair Value, Less Than 12 Months	28.8	73.4
Gross Unrealized Loss, Less Than 12 Months	-0.5	-1.3
Number of Securities, 12 Months or Greater	5	0
Estimated Fair Value, 12 Months or Greater	17	0
Gross Unrealized Losses, 12 Months or Greater	-0.5	0
Fixed Maturities [Member] | States, Municipalities And Political Subdivisions, Tax-Exempt [Member]	'	'
Schedule of Investments [Line Items]	'	'
Number of Securities, Less Than 12 Months	496	806
Estimated Fair Value, Less Than 12 Months	1,351	2,070.90
Gross Unrealized Loss, Less Than 12 Months	-33.3	-90.1
Number of Securities, 12 Months or Greater	73	42
Estimated Fair Value, 12 Months or Greater	168	82.4
Gross Unrealized Losses, 12 Months or Greater	-9.5	-9.6
Fixed Maturities [Member] | Corporate Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Number of Securities, Less Than 12 Months	1,215	1,448
Estimated Fair Value, Less Than 12 Months	2,198.90	2,586.60
Gross Unrealized Loss, Less Than 12 Months	-54.8	-95.2
Number of Securities, 12 Months or Greater	102	107
Estimated Fair Value, 12 Months or Greater	127.9	81.3
Gross Unrealized Losses, 12 Months or Greater	-14.1	-15.5
Fixed Maturities [Member] | Residential Mortgage-Backed Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Number of Securities, Less Than 12 Months	490	605
Estimated Fair Value, Less Than 12 Months	985.9	1,243
Gross Unrealized Loss, Less Than 12 Months	-26.8	-41.4
Number of Securities, 12 Months or Greater	74	80
Estimated Fair Value, 12 Months or Greater	115.1	116.2
Gross Unrealized Losses, 12 Months or Greater	-5.5	-7.1
Fixed Maturities [Member] | Commercial Mortgage-Backed Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Number of Securities, Less Than 12 Months	37	52
Estimated Fair Value, Less Than 12 Months	112.4	177.7
Gross Unrealized Loss, Less Than 12 Months	-1.1	-2.6
Number of Securities, 12 Months or Greater	4	4
Estimated Fair Value, 12 Months or Greater	4.8	5.6
Gross Unrealized Losses, 12 Months or Greater	-0.2	-0.3
Fixed Maturities [Member] | Other Debt Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Number of Securities, Less Than 12 Months	61	65
Estimated Fair Value, Less Than 12 Months	177.7	185.3
Gross Unrealized Loss, Less Than 12 Months	-2.8	-2.5
Number of Securities, 12 Months or Greater	19	17
Estimated Fair Value, 12 Months or Greater	17.1	16.2
Gross Unrealized Losses, 12 Months or Greater	($0.80)	($0.80)

Investments_Amortized_Cost_And

Investments (Amortized Cost And Fair Value Of Fixed Maturity Securities, By Contractual Maturity) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Schedule of Investments [Line Items]	'	'
Available-for-sale securities, Amortized Cost	$19,506.20	$18,478.50
Available-for-sale securities, Estimated Fair Value	20,500.90	19,254.90
Fixed Maturities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Due in one year or less, Amortized Cost	444	'
Due after one year through five years, Amortized Cost	4,580.90	'
Due after five years through ten years, Amortized Cost	5,077.60	'
Due after ten years, Amortized Cost	5,333.50	'
Mortgage-backed securities, Amortized Cost	2,669.40	'
Available-for-sale securities, Amortized Cost	18,105.40	17,282.60
Due in one year or less, Estimated Fair Value	447.4	'
Due after one year through five years, Estimated Fair Value	4,714.90	'
Due after five years through ten years, Estimated Fair Value	5,230.70	'
Due after ten years, Estimated Fair Value	5,412.60	'
Mortgage-backed securities, Estimated Fair Value	2,700.80	'
Available-for-sale securities, Estimated Fair Value	$18,506.40	$17,488.10

Investments_Proceeds_and_Reali

Investments (Proceeds and Realized Gains Losses From Investments) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Investments [Abstract]	'	'
Proceeds	$2,401.40	$3,117.60
Gross realized gains	82.9	107
Gross realized losses	$41.20	$90.20

Investments_Narrative_Details

Investments (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Schedule of Investments [Line Items]	'	'	'
Available-for-sale Securities	$20,500.90	'	$19,254.90
Net unrealized gains on investments	649.3	838	'
Other-than-temporary impairment losses recognized in income	10.8	37.9	'
Mortgage-Backed Securities [Member]	'	'	'
Schedule of Investments [Line Items]	'	'	'
Available-for-sale Securities	2,700.80	'	'
Asset-Backed Securities [Member]	'	'	'
Schedule of Investments [Line Items]	'	'	'
Available-for-sale Securities	501.5	'	'
Sub-Prime Mortgage-Backed and Asset-Backed Securities [Member]	'	'	'
Schedule of Investments [Line Items]	'	'	'
Available-for-sale Securities	30	'	'
Unrealized Gain (Loss) on Securities	1.3	'	'
Alt-A Mortgage-Backed and Asset-Backed Securities [Member]	'	'	'
Schedule of Investments [Line Items]	'	'	'
Available-for-sale Securities	98.8	'	'
Unrealized Gain (Loss) on Securities	$7.10	'	'

Fair_Value_Fair_Value_Measurem

Fair Value (Fair Value Measurements By Level For Assets Measured At Fair Value On A Recurring Basis) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Level I [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash equivalents	$612.40	$632.30
Securities lending collateral	532	408.5
Long-term receivable (reported with other assets)	0	'
Total assets	3,481.40	2,868.30
Total liabilities	0	0
Level I [Member] | Other Derivative Instruments [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivatives excluding embedded options (reported with other assets)	0	0
Derivatives excluding embedded options (reported with other liabilities)	0	0
Level I [Member] | Short-term Investments [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Other invested assets, current	25.9	16.3
Level I [Member] | Equity Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	1,766.20	1,475.70
Level I [Member] | Fixed Maturities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	544.9	335.5
Level I [Member] | Fixed Maturities [Member] | United States Government Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	461.6	299.9
Level I [Member] | Fixed Maturities [Member] | Government Sponsored Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis 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]	'	'
Fair value assets measured on recurring basis 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]	'	'
Fair value assets measured on recurring basis available-for-sale securities	12	0
Level I [Member] | Fixed Maturities [Member] | Options Embedded In Convertible Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	0	0
Level I [Member] | Fixed Maturities [Member] | Residential Mortgage-Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis 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]	'	'
Fair value assets measured on recurring basis available-for-sale securities	0	0
Level I [Member] | Fixed Maturities [Member] | Other Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	71.3	35.6
Level II [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash equivalents	0	0
Securities lending collateral	793	561.3
Long-term receivable (reported with other assets)	0	'
Total assets	18,836.70	17,885.50
Total liabilities	-20.9	-20.7
Level II [Member] | Other Derivative Instruments [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivatives excluding embedded options (reported with other assets)	29	58.4
Derivatives excluding embedded options (reported with other liabilities)	-20.9	-20.7
Level II [Member] | Short-term Investments [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Other invested assets, current	0	0
Level II [Member] | Equity Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	185.1	249.7
Level II [Member] | Fixed Maturities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	17,829.60	17,016.10
Level II [Member] | Fixed Maturities [Member] | United States Government Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	0	0
Level II [Member] | Fixed Maturities [Member] | Government Sponsored Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	168.2	173.5
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]	'	'
Fair value assets measured on recurring basis available-for-sale securities	6,003.50	6,002.70
Level II [Member] | Fixed Maturities [Member] | Corporate Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	8,375.90	7,593.40
Level II [Member] | Fixed Maturities [Member] | Options Embedded In Convertible Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	97.6	89.2
Level II [Member] | Fixed Maturities [Member] | Residential Mortgage-Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	2,181.60	2,268.90
Level II [Member] | Fixed Maturities [Member] | Commercial Mortgage-Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	516.1	480.1
Level II [Member] | Fixed Maturities [Member] | Other Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	486.7	408.3
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
Long-term receivable (reported with other assets)	21.6	'
Total assets	196.7	177.9
Total liabilities	0	0
Level III [Member] | Other Derivative Instruments [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivatives excluding embedded options (reported with other assets)	0	0
Derivatives excluding embedded options (reported with other liabilities)	0	0
Level III [Member] | Short-term Investments [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Other invested assets, current	0	0
Level III [Member] | Equity Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	43.2	41.4
Level III [Member] | Fixed Maturities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	131.9	136.5
Level III [Member] | Fixed Maturities [Member] | United States Government Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis 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]	'	'
Fair value assets measured on recurring basis 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]	'	'
Fair value assets measured on recurring basis 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]	'	'
Fair value assets measured on recurring basis available-for-sale securities	114	115.2
Level III [Member] | Fixed Maturities [Member] | Options Embedded In Convertible Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	0	0
Level III [Member] | Fixed Maturities [Member] | Residential Mortgage-Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	0	0
Level III [Member] | Fixed Maturities [Member] | Commercial Mortgage-Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	3.1	6.5
Level III [Member] | Fixed Maturities [Member] | Other Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	14.8	14.8
Total [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash equivalents	612.4	632.3
Securities lending collateral	1,325	969.8
Long-term receivable (reported with other assets)	21.6	'
Total assets	22,514.80	20,931.70
Total liabilities	-20.9	-20.7
Total [Member] | Other Derivative Instruments [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivatives excluding embedded options (reported with other assets)	29	58.4
Derivatives excluding embedded options (reported with other liabilities)	-20.9	-20.7
Total [Member] | Short-term Investments [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Other invested assets, current	25.9	16.3
Total [Member] | Equity Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	1,994.50	1,766.80
Total [Member] | Fixed Maturities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	18,506.40	17,488.10
Total [Member] | Fixed Maturities [Member] | United States Government Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	461.6	299.9
Total [Member] | Fixed Maturities [Member] | Government Sponsored Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	168.2	173.5
Total [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]	'	'
Fair value assets measured on recurring basis available-for-sale securities	6,003.50	6,002.70
Total [Member] | Fixed Maturities [Member] | Corporate Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	8,501.90	7,708.60
Total [Member] | Fixed Maturities [Member] | Options Embedded In Convertible Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	97.6	89.2
Total [Member] | Fixed Maturities [Member] | Residential Mortgage-Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	2,181.60	2,268.90
Total [Member] | Fixed Maturities [Member] | Commercial Mortgage-Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	519.2	486.6
Total [Member] | Fixed Maturities [Member] | Other Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value assets measured on recurring basis available-for-sale securities	$572.80	$458.70

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 $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Beginning balance	$177.90	$155.50
Total gains (losses) recognized in net income	18	0.9
Total gains (losses) recognized in accumulated other comprehensive income	-2.5	-1.3
Purchases	18.3	10
Sales	-2.8	-2.5
Settlements	-5.7	-10.9
Transfers into Level III	0	13.1
Transfers out of Level III	-6.5	-2.9
Ending balance	196.7	161.9
Change in unrealized losses included in net income related to assets still held	-4.3	-1.4
Corporate Securities [Member]	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Beginning balance	115.2	121.1
Total gains (losses) recognized in net income	-3.3	0.3
Total gains (losses) recognized in accumulated other comprehensive income	3.1	-0.6
Purchases	9.3	9.6
Sales	-1.7	0
Settlements	-2.1	-9.1
Transfers into Level III	0	0
Transfers out of Level III	-6.5	0
Ending balance	114	121.3
Change in unrealized losses included in net income related to assets still held	-4	0
Residential Mortgage-Backed Securities [Member]	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Beginning balance	0	4.3
Total gains (losses) recognized in net income	0	0
Total gains (losses) recognized in accumulated other comprehensive income	0	0
Purchases	0	0
Sales	0	0
Settlements	0	-1.6
Transfers into Level III	0	13.1
Transfers out of Level III	0	-2.9
Ending balance	0	12.9
Change in unrealized losses included in net income related to assets still held	0	0
Commercial Mortgage-Backed Securities [Member]	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Beginning balance	6.5	0
Total gains (losses) recognized in net income	0	0
Total gains (losses) recognized in accumulated other comprehensive income	0	0
Purchases	0	0
Sales	0	0
Settlements	-3.4	0
Transfers into Level III	0	0
Transfers out of Level III	0	0
Ending balance	3.1	0
Change in unrealized losses included in net income related to assets still held	0	0
Other Debt Securities [Member]	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Beginning balance	14.8	3.9
Total gains (losses) recognized in net income	0	0
Total gains (losses) recognized in accumulated other comprehensive income	0.2	0.2
Purchases	0	0
Sales	0	0
Settlements	-0.2	-0.2
Transfers into Level III	0	0
Transfers out of Level III	0	0
Ending balance	14.8	3.9
Change in unrealized losses included in net income related to assets still held	0	0
Equity Securities [Member]	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Beginning balance	41.4	26.2
Total gains (losses) recognized in net income	-0.3	0.6
Total gains (losses) recognized in accumulated other comprehensive income	-5.8	-0.9
Purchases	9	0.4
Sales	-1.1	-2.5
Settlements	0	0
Transfers into Level III	0	0
Transfers out of Level III	0	0
Ending balance	43.2	23.8
Change in unrealized losses included in net income related to assets still held	-0.3	-1.4
Long Term Receivable [Member]	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Beginning balance	0	0
Total gains (losses) recognized in net income	21.6	0
Total gains (losses) recognized in accumulated other comprehensive income	0	0
Purchases	0	0
Sales	0	0
Settlements	0	0
Transfers into Level III	0	0
Transfers out of Level III	0	0
Ending balance	21.6	0
Change in unrealized losses included in net income related to assets still held	$0	'

Retirement_Benefits_Components

Retirement Benefits (Components Of Net Periodic Benefit (Credit) Cost) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Defined Benefit Plan Disclosure [Line Items]	'	'
Document Fiscal Year Focus	'2014	'
Pension Benefits [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Service cost	$3.30	$3.60
Interest cost	18.5	16.7
Expected return on assets	-34.4	-33.3
Recognized actuarial loss	5.3	8.6
Settlement loss	1.1	3.4
Amortization of prior service credit	-0.2	-0.2
Net periodic (credit) benefit cost	-6.4	-1.2
Other Benefits [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Service cost	0.8	1.6
Interest cost	6.6	5.6
Expected return on assets	-5.8	-5.5
Recognized actuarial loss	2.3	2.8
Settlement loss	0	0
Amortization of prior service credit	-3.6	-3.3
Net periodic (credit) benefit cost	$0.30	$1.20

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 $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Other invested assets, long-term	$1,593.80	$1,542.60
Short-term borrowings	590	400
Convertible debentures	968.1	'
Carrying Value [Member]	'	'
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Other invested assets, long-term	1,593.80	1,542.60
Short-term borrowings	590	400
Commercial paper	758.6	379.2
Notes	12,724.10	12,746.40
Convertible debentures	968.1	966
Level I [Member]	'	'
Fair Value Balance Sheet Grouping Financial Statement Captions [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
Level II [Member]	'	'
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Other invested assets, long-term	0	0
Short-term borrowings	590	400
Commercial paper	758.6	379.2
Notes	13,285.10	13,014.30
Convertible debentures	2,192.80	2,030.60
Level III [Member]	'	'
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Other invested assets, long-term	1,593.80	1,542.60
Short-term borrowings	0	0
Commercial paper	0	0
Notes	0	0
Convertible debentures	0	0
Total [Member]	'	'
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Other invested assets, long-term	1,593.80	1,542.60
Short-term borrowings	590	400
Commercial paper	758.6	379.2
Notes	13,285.10	13,014.30
Convertible debentures	$2,192.80	$2,030.60

Income_Taxes_Narrative_Details

Income Taxes (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Income Tax Disclosure [Abstract]	'	'
Income Tax Expense (Benefit)	$438.70	$410.20
Effective tax rate	38.80%	32.00%
Health Insurance Provider fee, nondeductible expense	$80.50	'

Debt_Carrying_Value_Of_Longter

Debt (Carrying Value Of Long-term Debt) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Debt Instrument [Line Items]	'	'
Current portion of long-term debt	($518.70)	($518)
Long-term debt, less current portion	$13,932.10	$13,573.60

Debt_Narrative_Details

Debt (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Debt Instrument [Line Items]	'	'
Senior unsecured notes, carrying value	$12,699.20	'
Senior unsecured notes, principal amount repurchased	21.2	'
Senior unsecured notes, repurchase price	24.2	'
Loss on extinguishment of debt	3	0
Unsecured surplus note, carrying amount	24.9	'
Senior Revolving Credit	'	'
Debt Instrument [Line Items]	'	'
Line of credit facility, maximum borrowing capacity	2,000	'
Line of credit maturity date	29-Sep-16	'
Commercial Paper Program	'	'
Debt Instrument [Line Items]	'	'
Commercial paper authorized	2,500	'
Commercial paper	$758.60	'

Debt_Convertible_Debenture_Ter

Debt (Convertible Debenture Terms) (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014
Debt Instruments [Abstract]	'
Outstanding principal amount	$1,500
Unamortized debt discount	531.9
Net debt carrying amount	968.1
Equity component carrying amount	$543.60
Conversion rate (shares of common stock per $1,000 of principal)	13.3135
Effective conversion price (per $1,000 of principal amount) per share	$75.11

Commitments_And_Contingencies_

Commitments And Contingencies (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014
International Business Machines Corporation [Member]	'
Commitments And Contingencies [Line Items]	'
Long-term purchase commitment, amount	$214.70
Affiliated Computer Services, Inc. [Member]	'
Commitments And Contingencies [Line Items]	'
Long-term purchase commitment initiation date	'March 31, 2009
Long-term purchase commitment, amount	125.7
Long Term Purchase Commitment Expiration Date	31-Mar-16
Minimum [Member]	'
Commitments And Contingencies [Line Items]	'
Possible losses, in excess of established reserves, minimum	0
Maximum [Member]	'
Commitments And Contingencies [Line Items]	'
Possible losses, in excess of established reserves, maximum	$250
In re WellPoint, Inc. Out-of-Network UCR Rates Litigation [Member]	'
Commitments And Contingencies [Line Items]	'
Number of putative class actions consolidated into a single lawsuit	11

Capital_Stock_Summary_of_Cash_

Capital Stock (Summary of Cash Dividend Activity) (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Capital [Abstract]	'	'
Declaration date	28-Jan-14	20-Feb-13
Record date	10-Mar-14	8-Mar-13
Payment date	25-Mar-14	25-Mar-13
Cash dividend per share	$0.44	$0.38
Total payment	$123.40	$113.40

Capital_Stock_Summary_of_Share

Capital Stock (Summary of Share Repurchases) (Details) (USD $)	3 Months Ended		0 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Apr. 15, 2014
			Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]	'	'	'
Shares repurchased	14.3	5.5	2.3
Average price per share	$88.14	$62.41	$98.03
Aggregate cost	$1,262.80	$340.20	$220.80
Authorization remaining at the end of each period	$2,428.20	$1,496.60	$2,207.40

Capital_Stock_Summary_of_Stock

Capital Stock (Summary of Stock Option Activity) (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]	'
Outstanding at beginning of period, Number of Shares	10
Granted, Number of Shares	1.7
Exercised, Number of Shares	-2
Forfeited or expired, Number of Shares	-0.1
Outstanding at end of period, Number of Shares	9.6
Exercisable at end of period, Number of Shares	6.3
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]	'
Outstanding at beginning of period, Weighted-Average Option Price per Share	$65.38
Granted, Weighted-Average Option Price per Share	$89.44
Exercised, Weighted-Average Option Price per Share	$66.39
Forfeited or expired, Weighted-Average Option Price per Share	$62.71
Outstanding at end of period, Weighted-Average Option Price per Share	$69.46
Exercisable at end of period, Weighted-Average Option Price per Share	$65.72
Outstanding at end of period, Weighted-Average Remaining Contractual Life	'3 years 11 months
Exercisable at end of period, Weighted-Average Remaining Contractual Life	'2 years 7 months
Outstanding at end of period, Aggregate Intrinsic Value	$289.60
Exercisable at end of period, Aggregate Intrinsic Value	$212.60

Capital_Stock_Nonvested_Restri

Capital Stock (Nonvested Restricted Stock Activity Including Restricted Stock Units) (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]	'	'
Nonvested at Beginning Balance, Restricted Stock Shares and Units	4.2	'
Granted, Restricted Stock Shares and Units	1.3	'
Vested, Restricted Stock Shares And Units	-1.5	'
Forfeited, Restricted Stock Shares And Units	-0.3	'
Nonvested at Ending Balance, Restricted Stock Shares and Units	3.7	'
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]	'	'
Nonvested at Beginning Balance, Weighted-Average Grant Date Fair Value per Share	$63.83	'
Granted, Weighted-Average Grant Date Fair Value per Share	$89.43	$61.81
Vested, Weighted-Average Grant Date Fair Value per Share	$64.15	'
Forfeited, Weighted-Average Grant Date Fair Value per Share	$63.33	'
Nonvested at Ending Balance, Weighted-Average Grant Date Fair Value per Share	$72.51	'

Capital_Stock_Fair_Values_of_O

Capital Stock (Fair Values of Options Granted During The Period Estimated Using Weighted-Average Assumptions) (Details)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Capital [Abstract]	'	'
Document Fiscal Year Focus	'2014	'
Risk-free interest rate	2.16%	1.25%
Volatility factor	35.00%	35.00%
Quarterly dividend yield	0.50%	0.60%
Weighted-average expected life (years)	'3 years 9 months	'4 years 0 months

Capital_Stock_Schedule_Of_Weig

Capital Stock (Schedule Of Weighted-Average Fair Values Determined For The Periods) (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Capital [Abstract]	'	'
Document Fiscal Year Focus	'2014	'
Options granted during the period	$22.20	$14.51
Restricted stock and stock awards granted during the period	$89.43	$61.81

Capital_Stock_Capital_Stock_Na

Capital Stock Capital Stock (Narrative) (Details) (USD $)	0 Months Ended	3 Months Ended
In Millions, unless otherwise specified	Feb. 04, 2014	Mar. 31, 2014
Capital [Abstract]	'	'
ASR Agreement, Authorized Amount	$600	'
Stock Repurchased and Retired Under ASR Agreement During Period, Shares	'	6.6

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income (Loss) (Reconciliation Of The Components Of Accumulated Other Comprehensive Income) (Details) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]	'	'	'
investments, gross unrealized gains	$1,156.50	$1,324.30	$1,054.20
Investments, gross unrealized losses	-161.8	-53.1	'
Investments, net pretax unrealized gains	994.7	1,271.20	'
Deferred tax liability	-345.4	-433.2	'
Net unrealized gains on investments	649.3	838	'
Cash flow hedges, gross unrealized losses	-48.6	-53	'
Cash flow hedges, deferred tax asset	17	18.6	'
Net unrealized losses on cash flow hedges	-31.6	-34.4	'
Defined benefit pension plans, deferred net actuarial loss	-426.4	-674.8	'
Defined benefit pension plans, deferred prior service credits	8.4	3.7	'
Defined benefit pension plans, deferred tax asset	167.5	264.4	'
Net unrecognized periodic benefit costs for defined benefit pension plans	-250.5	-406.7	'
Postretirement benefit plans, deferred net actuarial loss	-154.7	-188.3	'
Postretirement benefit plans, deferred prior service credits	86.2	99.8	'
Defined benefit pension plans, deferred tax asset	27.4	34.8	'
Net unrecognized periodic benefit costs for postretirement benefit plans	-41.1	-53.7	'
Foreign currency translation adjustments, gross unrealized gains (losses)	2	-1.1	'
Foreign currency translation adjustments, deferred tax (liability) asset	-0.7	0.4	'
Net unrealized gains (losses) on foreign currency translation adjustments	1.3	-0.7	'
Accumulated other comprehensive income	$327.40	$342.50	$183.20

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income (Loss) (Other Comprehensive Income (Loss) Reclassification Adjustments) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]	'	'
Net holding gain on investment securities arising during the period, net of tax expense of ($67.5) and ($2.4), respectively	$120.20	$29.70
Reclassification adjustment for net realized gain on investment securities, net of tax expense of ($10.8) and ($2.6), respectively	20.1	4.8
Total reclassification adjustment on investments	140.3	34.5
Non-credit component of other-than-temporary impairments on investments, net of tax expense of ($0.3) and ($1.2), respectively	0.5	2.2
Cash flow hedges, holding gain, net of tax expense of ($0.4) and ($0.4), respectively	0.7	0.7
Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, net of tax expense of ($1.9) and ($4.4), respectively	2.9	6.8
Foreign currency translation adjustment, net of tax benefit of $0.0 and $0.5, respectively	-0.2	-0.8
Net gain (loss) recognized in other comprehensive income (loss), net of tax expense (benefit)	$144.20	$43.40

Accumulated_Other_Comprehensiv4

Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) Reclassification Adjustments (Parantheticals) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) Reclassification Adjustments (Parantheticals) [Abstract]	'	'
Net holding gain on investment securities arising during the period, tax expense	$67.50	$2.40
Reclassification adjustment for net realized gain on investment securities, tax expense	10.8	2.6
Non-credit component of dther than temporary impairments on investments, tax expense	0.3	1.2
Cash flow hedges, holding gain, tax expense	0.4	0.4
Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, tax expense	1.9	4.4
foreign currency translation adjustment, tax benefit	0	-0.5
Net gain recognized in other comprehensive income, tax expense	$80.90	$10.50

Earnings_Per_Share_Denominator

Earnings Per Share (Denominator For Basic And Diluted Earnings Per Share) (Details)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]	'	'
Denominator for basic earnings per share - weighted average shares	284.9	303.2
Effect of dilutive securities – employee stock options, non-vested restricted stock awards and convertible debentures	7.7	2.7
Denominator for diluted earnings per share	292.6	305.9

Earnings_Per_Share_Narrative_D

Earnings Per Share (Narrative) (Details)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]	'	'
Weighted average shares excluded from denominator for diluted earnings per share because the stock options were anti-dilutive	0.6	11.5
Restricted stock units issued under stock incentive plan	1.3	'
Restricted stock units excluded from the denominator for diluted earnings per share	0.7	'

Segment_Information_Financial_

Segment Information (Financial Data By Reportable Segment) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]	'	'
Operating revenue	$17,644.80	$17,435.10
Operating gain (loss)	1,118.70	1,357.30
Commercial and Specialty Business [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Operating revenue	9,697.50	9,859.40
Operating gain (loss)	886.1	1,262.10
Government Business [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Operating revenue	7,941.30	7,569.40
Operating gain (loss)	239.6	102.6
Other [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Operating revenue	6	6.3
Operating gain (loss)	($7)	($7.40)

Segment_Information_Reconcilia

Segment Information (Reconciliation Of Reportable Segments Operating Revenues To Total Revenues Reported In The Consolidated Statements Of Income) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting [Abstract]	'	'
Reportable segments operating revenues	$17,644.80	$17,435.10
Net investment income	183.7	162
Net realized gains on investments	41.7	16.8
Other-than-temporary impairment losses recognized in income	-10.8	-37.9
Total revenues	$17,859.40	$17,576

Segment_Information_Reconcilia1

Segment Information (Reconciliation Of Reportable Segments Operating Gain To Income Before Income Tax Expense Included In The Consolidated Statements Of Income) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting [Abstract]	'	'
Reportable segments operating gain	$1,118.70	$1,357.30
Net investment income	183.7	162
Net realized gains on investments	41.7	16.8
Other-than-temporary impairment losses recognized in income	-10.8	-37.9
Interest expense	-146.2	-153.5
Amortization of other intangible assets	-54	-62.2
Loss on extinguishment of debt	-3	0
Income from continuing operations before income tax expense	$1,130.10	$1,282.50