Elevance Health (ELV) 10-Q29 Apr 152015 Q1 Quarterly reportFinancial data

Company Profile

Document_And_Entity_Informatio

Document And Entity Information	3 Months Ended
Document And Entity Information	Mar. 31, 2015	Apr. 14, 2015
Document and Entity Information
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	ANTM
Entity Registrant Name	Anthem, Inc.
Entity Central Index Key	1156039
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	264,905,598	264,536,271

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$1,397	$2,151.70
Investments available-for-sale, at fair value:
Fixed maturity securities (amortized cost of $18,333.2 and $17,120.4)	18,804.70	17,467.40
Equity securities (cost of $1,521.8 and $1,303.7)	2,103.40	1,906.60
Other invested assets, current	25.4	20.2
Accrued investment income	173.8	161.4
Premium and self-funded receivables	4,964.60	4,825.50
Other receivables	2,549.70	2,117
Income taxes receivable	0	308.9
Securities lending collateral	2,023.60	1,515.20
Deferred tax assets, net	164.1	280.4
Other current assets	2,534.10	1,474.60
Total current assets	34,740.40	32,228.90
Long-term investments available-for-sale, at fair value:
Fixed maturity securities (amortized cost of $523.6 and $500.7)	529.3	504.4
Equity securities (cost of $27.0 and $27.0)	31.5	31.5
Other invested assets, long-term	1,718.40	1,695.90
Property and equipment, net	1,915.90	1,944.30
Goodwill	17,570.90	17,082
Other intangible assets	8,293.60	7,958.10
Other noncurrent assets	746	619.9
Total assets	65,546	62,065
Liabilities and shareholders' equity
Medical claims payable	7,177.10	6,861.20
Reserves for future policy benefits	68.1	68.1
Other policyholder liabilities	2,782.50	2,626.50
Total policy liabilities	10,027.70	9,555.80
Unearned income	1,079.80	1,078.10
Accounts payable and accrued expenses	4,454.70	3,651.80
Income taxes payable	283.8	0
Security trades pending payable	189.3	66.2
Securities lending payable	2,023.40	1,515.30
Short-term borrowings	450	400
Current portion of long-term debt	625	625
Other current liabilities	2,171.70	1,861.20
Total current liabilities	21,305.40	18,753.40
Long-term debt, less current portion	14,764.40	14,127.20
Reserves for future policy benefits, noncurrent	684.8	671.3
Deferred tax liabilities, net	3,357.70	3,226
Other noncurrent liabilities	1,099.40	1,035.80
Total liabilities	41,211.70	37,813.70
Commitment and contingencies-Note 9
Shareholders' equity
Preferred stock, without par value, shares authorized â€“ 100,000,000; shares issued and outstanding â€“ none	0	0
Common stock, par value $0.01, shares authorized â€“ 900,000,000; shares issued and outstanding â€“ 264,905,598 and 268,109,932	2.6	2.7
Additional paid-in capital	9,943.70	10,062.30
Retained earnings	14,150.10	14,014.40
Accumulated other comprehensive income	237.9	171.9
Total shareholders' equity	24,334.30	24,251.30
Total liabilities and shareholders' equity	$65,546	$62,065

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Available-for-sale fixed maturity securities investments, current, amortized cost	$18,333.20	$17,120.40
Available-for-sale equity securities investments, current, cost	1,521.80	1,303.70
Available-for-sale fixed maturity securities investments, long-term, amortized cost	523.6	500.7
Available-for-sale equity securities investments, long-term, cost	$27	$27
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	264,905,598	268,109,932
Common stock, shares outstanding	264,905,598	268,109,932

Consolidated_Statements_Of_Inc

Consolidated Statements Of Income (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Revenues
Premiums	$17,610.50	$16,517
Administrative fees	1,227.10	1,118.30
Other revenue	13.8	9.5
Total operating revenue	18,851.40	17,644.80
Net investment income	167.6	183.7
Net realized gains on investments	46.5	41.7
Other-than-temporary impairment losses on investments:
Total other-than-temporary impairment losses on investments	-15.4	-10.8
Portion of other-than-temporary impairment losses recognized in other comprehensive income	1.4	0
Other-than-temporary impairment losses recognized in income	-14	-10.8
Total revenues	19,051.50	17,859.40
Expenses
Benefit expense	14,126.90	13,664.60
Selling, general and administrative expense:
Selling expense	368.2	370.8
General and administrative expense	2,777	2,490.70
Total selling, general and administrative expense	3,145.20	2,861.50
Interest expense	154.4	146.2
Amortization of other intangible assets	52.5	54
Loss on extinguishment of debt	3.4	3
Total expenses	17,482.40	16,729.30
Income from continuing operations before income tax expense	1,569.10	1,130.10
Income tax expense	703.9	438.7
Income from continuing operations	865.2	691.4
Income from discontinued operations, net of tax	0	9.6
Net income	$865.20	$701
Net income per share
Basic - continuing operations (in dollars per share)	$3.25	$2.43
Basic - discontinued operations (in dollars per share)	$0	$0.03
Basic net income per share	$3.25	$2.46
Diluted - continuing operations (in dollars per share)	$3.09	$2.37
Diluted - discontinued operations (in dollars per share)	$0	$0.03
Diluted net income per share	$3.09	$2.40
Dividends per share	$0.63	$0.44

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$865.20	$701
Other comprehensive income, net of tax:
Change in net unrealized gains/losses on investments	60.4	140.3
Change in non-credit component of other-than-temporary impairment losses on investments	3.5	0.5
Change in net unrealized gains/losses on cash flow hedges	0.9	0.7
Change in net periodic pension and postretirement costs	4.7	2.9
Foreign currency translation adjustments	-3.5	-0.2
Other comprehensive income	66	144.2
Total comprehensive income	$931.20	$845.20

Consolidated_Statements_Of_Cas

Consolidated Statements Of Cash Flows (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating activities
Net income	$865.20	$701
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized gains on investments	-46.5	-41.7
Other-than-temporary impairment losses recognized in income	14	10.8
Loss on extinguishment of debt	3.4	3
Gain on disposal from discontinued operations	0	-3.2
Loss on disposal of assets	0.9	0.1
Deferred income taxes	70.6	85.2
Amortization, net of accretion	189.2	190.3
Depreciation expense	25.1	26.4
Impairment of property and equipment	0	2.1
Share-based compensation	27.1	38.8
Excess tax benefits from share-based compensation	-68.8	-22.4
Changes in operating assets and liabilities:
Receivables, net	-429.6	-616
Other invested assets	-10.1	-14.6
Other assets	-191	-69.5
Policy liabilities	382.9	545.6
Unearned income	-31.8	250
Accounts payable and accrued expenses	-189.4	-137.3
Other liabilities	401.1	107.4
Income taxes	635	356
Other, net	3.2	-24.5
Net cash provided by operating activities	1,650.50	1,387.50
Investing activities
Purchases of fixed maturity securities	-3,273.30	-3,084.80
Proceeds from fixed maturity securities:
Sales	2,065	2,061.20
Maturities, calls and redemptions	270.4	284.3
Purchases of equity securities	-1,051.50	-228.6
Proceeds from sales of equity securities	575.5	30.3
Purchases of other invested assets	-48.1	-35.4
Proceeds from sales of other invested assets	15	25.6
Settlement of non-hedging derivatives	-32	-46.2
Changes in securities lending collateral	-508	-354.9
Purchase of subsidiary, net of cash acquired	-635.8	0
Proceeds from sale of subsidiary, net of cash sold	0	740
Purchases of property and equipment	-88.8	-135.7
Other, net	0	-0.1
Net cash used in investing activities	-2,711.60	-744.3
Financing activities
Net proceeds from commercial paper borrowings	638.8	379.4
Repayments of long-term borrowings	-16.4	-24.2
Proceeds from short-term borrowings	850	970
Repayments of short-term borrowings	-800	-780
Changes in securities lending payable	508.1	354.9
Changes in bank overdrafts	-105.9	75
Premiums paid on equity call options	-12.8	0
Proceeds from equity put options	12.7	0
Repurchase and retirement of common stock	-774.1	-1,262.80
Cash dividends	-166.6	-123.4
Proceeds from issuance of common stock under employee stock plans	109.3	130.1
Excess tax benefits from share-based compensation	68.8	22.4
Net cash provided by (used in) financing activities	311.9	-258.6
Effect of foreign exchange rates on cash and cash equivalents	-5.5	-0.3
Change in cash and cash equivalents	-754.7	384.3
Cash and cash equivalents, at beginning of period	2,151.70	1,586.90
Cash and cash equivalents, at end of period	1,397	1,971.20
Cash and cash equivalents of continuing operations at end of period	$1,397

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 [Member]
In Millions, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]
Balance at Dec. 31, 2013	$24,765.20	$2.90	$10,765.20	$13,813.90	$183.20
Balance (in shares) at Dec. 31, 2013		293.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	701			701
Other comprehensive income	144.2				144.2
Settlement of equity options	-19.4		-19.4
Repurchase and retirement of common stock, shares	-14.3	-14.3
Repurchase and retirement of common stock, value	1,262.80	0	884.3	378.5
Dividends and dividend equivalents	-124.9			-124.9
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		2.9
Issuance of common stock under employee stock plans, net of related tax benefits	142	0	142
Balance at Mar. 31, 2014	24,345.30	2.9	10,003.50	14,011.50	327.4
Balance (in shares) at Mar. 31, 2014		281.9
Balance at Dec. 31, 2014	24,251.30	2.7	10,062.30	14,014.40	171.9
Balance (in shares) at Dec. 31, 2014		268.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	865.2			865.2
Other comprehensive income	66				66
Premiums for equity options	-12.8		-12.8
Repurchase and retirement of common stock, shares	-5.7	-5.7
Repurchase and retirement of common stock, value	774.1	0.1	212.4	561.6
Dividends and dividend equivalents	-167.9			-167.9
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		2.5
Issuance of common stock under employee stock plans, net of related tax benefits	106.6		106.6
Balance at Mar. 31, 2015	$24,334.30	$2.60	$9,943.70	$14,150.10	$237.90
Balance (in shares) at Mar. 31, 2015		264.9

Organization

Organization	3 Months Ended
Organization	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization
	References to the terms “we”, “our”, “us”, “Anthem” or the “Company” used throughout these Notes to Consolidated Financial Statements refer to Anthem, Inc., an Indiana corporation, and unless the context otherwise requires, its direct and indirect subsidiaries.
	We are one of the largest health benefits companies in terms of medical membership in the United States, serving 38.5 medical members through our affiliated health plans as of March 31, 2015. 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 dental, vision, life and disability insurance benefits, radiology benefit management and analytics-driven personal health care. We also provide services to the federal government in connection with the Federal Employee Program, or FEP. 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 arrangements with other BCBS licensees in the states of South Carolina and Texas. We conduct business through our AMERIGROUP Corporation, or Amerigroup, subsidiary, in Florida, Georgia, Kansas, Louisiana, Maryland, Nevada, New Jersey, New Mexico, New York, Tennessee, Texas and Washington. We also conduct business through our recently acquired Simply Healthcare Holdings, Inc., or Simply Healthcare, subsidiary in the state of Florida. We also serve customers throughout the country as HealthLink, UniCare (including a non-risk arrangement with the state of Massachusetts), 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
Basis Of Presentation and Significant Accounting Policies	Mar. 31, 2015
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 2014 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, 2015 and 2014 have been recorded. The results of operations for the three months ended March 31, 2015 are not necessarily indicative of the results that may be expected for the full year ending December 31, 2015. These unaudited consolidated financial statements should be read in conjunction with our audited consolidated financial statements for the year ended December 31, 2014 included in our 2014 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.
	Recent Accounting Guidance Not Yet Adopted: In April 2015, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update No. 2015-05, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement, or ASU 2015-05. This amendment provides guidance to help entities determine whether a cloud computing arrangement contains a software license that should be accounted for as internal-use software or as a service contract. ASU 2015-05 is effective for interim and annual reporting periods beginning after December 15, 2015, with early adoption permitted. Upon adoption, an entity has the option to apply the provisions of ASU 2015-05 either prospectively to all arrangements entered into or materially modified, or retrospectively. We will evaluate the effects, if any, the adoption of ASU 2015-05 will have upon our consolidated financial position, results of operations or cash flows.
	In April 2015, the FASB issued Accounting Standards Update No. 2015-03, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs, or ASU 2015-03. ASU 2015-03 amends current presentation guidance by requiring that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. ASU 2015-03 is effective for interim and annual reporting periods beginning after December 15, 2015, with early adoption permitted. In accordance with GAAP guidance currently in effect, debt issuance costs are included within other current assets and other noncurrent assets in our consolidated balance sheets. The adoption of ASU 2015-03 will not impact our consolidated financial position, results of operations or cash flows.
	In February 2015, the FASB issued Accounting Standards Update No. 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis, or ASU 2015-02. ASU 2015-02 amends current consolidation guidance by modifying the evaluation of whether limited partnerships and similar legal entities are variable interest entities or voting interest entities, eliminating the presumption that a general partner should consolidate a limited partnership, and affects the consolidation analysis of reporting entities that are involved with variable interest entities. ASU No. 2015-02 is effective for interim and annual reporting periods beginning after December 15, 2015, with early adoption permitted. All legal entities are subject to reevaluation under the revised consolidation model. The adoption of ASU 2015-02 is not expected to have a material impact on our consolidated financial position, results of operations or cash flows.
	There were no other new accounting pronouncements that were issued or became effective since the issuance of our 2014 Annual Report on Form 10-K that had, or are expected to have, a material impact on our consolidated financial position, results of operations or cash flows.

Business_Acquisition_and_Dives

Business Acquisition and Divestiture	3 Months Ended
Business Acquisition and Divestiture	Mar. 31, 2015
Business Combinations [Abstract]
Business Acquisition and Divestiture	Business Acquisition and Divestiture
	Simply Healthcare
	On February 17, 2015, we completed our acquisition of Simply Healthcare, a leading managed care company for people enrolled in Medicaid and Medicare programs in the state of Florida. This acquisition aligns with our strategy for continued growth in our Government Business segment.
	In accordance with FASB accounting guidance for business combinations, the preliminary consideration transferred was allocated to the fair value of Simply Healthcare's assets acquired and liabilities assumed, including identifiable intangible assets. The excess of the consideration transferred over the fair value of net assets acquired resulted in preliminary non-tax-deductible goodwill of $488.9 at March 31, 2015, all of which was allocated to our Government Business segment. Preliminary goodwill recognized from the acquisition of Simply Healthcare primarily relates to the future economic benefits arising from the assets acquired and is consistent with our stated intentions to strengthen our position and expand operations in the government sector to service Medicaid and Medicare enrollees. Any additional payments or receipts of cash resulting from contractual purchase price adjustments or any subsequent adjustments made to the assets acquired and liabilities assumed during the measurement period will be recorded as an adjustment to goodwill.
	The preliminary fair value of the net assets acquired from Simply Healthcare includes $388.0 of other intangible assets, which primarily consist of indefinite-lived state licenses and finite-lived customer relationships with amortization periods ranging from 3 to 4 years.
	The results of operations of Simply Healthcare are included in our consolidated financial statements within our Government Business segment for the period following February 17, 2015. The pro-forma effects of this acquisition for prior periods were not material to our consolidated results of operations.
	1-800 CONTACTS
	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 sales were 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. The operating results for 1-800 CONTACTS for the one month ended January 31, 2014 are reported as discontinued operations in the accompanying consolidated statements of income. The operating results for 1-800 CONTACTS were previously reported in our Commercial and Specialty Business segment.

Investments

Investments	3 Months Ended
	Mar. 31, 2015
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 $14.0 and $10.8 for the three months ended March 31, 2015 and 2014, respectively. There were no individually significant other-than-temporary impairment losses on investments by issuer during the three months ended March 31, 2015 and 2014. We continue to review our investment portfolios under our impairment review policy. Given the inherent uncertainty of changes in market conditions and the significant judgments involved, there is a continuing risk that 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, 2015 and December 31, 2014 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, 2015
	Fixed maturity securities:
	United States Government securities	$	372.8			$	7			$	(0.1	)	$	—		$	379.7			$	—

	Government sponsored securities	113.6				1.2				—			(0.2		)	114.6				—

	States, municipalities and political subdivisions, tax-exempt	5,532.40				291.4				(5.0		)	(1.6		)	5,817.20				—

	Corporate securities	9,587.50				213.4				(76.5		)	(31.9		)	9,692.50				(1.4		)

	Options embedded in convertible debt securities	7				—				—			—			7				—

	Residential mortgage-backed securities	2,054.90				74.6				(1.6		)	(4.6		)	2,123.30				—

	Commercial mortgage-backed securities	494				7.2				(0.3		)	(0.1		)	500.8				—

	Other debt securities	694.6				6.3				(0.9		)	(1.1		)	698.9				—

	Total fixed maturity securities	18,856.80				601.1				(84.4		)	(39.5		)	19,334.00				$	(1.4	)

	Equity securities	1,548.80				597.7				(11.6		)	—			2,134.90

	Total investments, available-for-sale	$	20,405.60			$	1,198.80			$	(96.0	)	$	(39.5	)	$	21,468.90

	December 31, 2014
	Fixed maturity securities:
	United States Government securities	$	315.7			$	4.6			$	(0.3	)	$	—		$	320			$	—

	Government sponsored securities	94.6				0.8				—			(0.4		)	95				—

	States, municipalities and political subdivisions, tax-exempt	5,451.40				287				(1.8		)	(3.0		)	5,733.60				—

	Corporate securities	8,335.90				162.9				(123.1		)	(43.2		)	8,332.50				(6.8		)

	Options embedded in convertible debt securities	98.7				—				—			—			98.7				—

	Residential mortgage-backed securities	2,099.70				68.9				(1.0		)	(8.6		)	2,159.00				—

	Commercial mortgage-backed securities	504.8				6.1				(0.6		)	(0.4		)	509.9				—

	Other debt securities	720.3				6.1				(1.7		)	(1.6		)	723.1				—

	Total fixed maturity securities	17,621.10				536.4				(128.5		)	(57.2		)	17,971.80				$	(6.8	)

	Equity securities	1,330.70				618.5				(11.1		)	—			1,938.10

	Total investments, available-for-sale	$	18,951.80			$	1,154.90			$	(139.6	)	$	(57.2	)	$	19,909.90

	At March 31, 2015, we owned $2,624.1 of mortgage-backed securities and $634.7 of asset-backed securities out of a total available-for-sale investment portfolio of $21,468.9. These securities included sub-prime and Alt-A securities with fair values of $36.1 and $73.1, respectively. These sub-prime and Alt-A securities had accumulated net unrealized gains of $1.4 and $4.7, respectively. The average credit rating of the sub-prime and Alt-A securities was “CCC” and “CC”, respectively.
	The following tables summarize for available-for-sale fixed maturity securities and available-for-sale equity securities in an unrealized loss position at March 31, 2015 and December 31, 2014, 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, 2015
Fixed maturity securities:
United States Government securities	10			$	48.5			$	(0.1	)		2		$	0.9		$	—

Government sponsored securities	5			5.3				—				10		21.4			(0.2		)

States, municipalities and political subdivisions, tax-exempt	161			427.3				(5.0		)		36		58.1			(1.6		)

Corporate securities	906			2,093.10				(76.5		)		256		360.7			(31.9		)

Residential mortgage-backed securities	105			224.7				(1.6		)		118		210.5			(4.6		)

Commercial mortgage-backed securities	26			99.9				(0.3		)		8		30.5			(0.1		)

Other debt securities	61			211.7				(0.9		)		18		52.2			(1.1		)

Total fixed maturity securities	1,274			3,110.50				(84.4		)		448		734.3			(39.5		)

Equity securities	445			232.3				(11.6		)		—		—			—

Total fixed maturity and equity securities	1,719			$	3,342.80			$	(96.0	)		448		$	734.3		$	(39.5	)

31-Dec-14
Fixed maturity securities:
United States Government securities	17			$	145.3			$	(0.3	)		2		$	0.9		$	—

Government sponsored securities	2			0.3				—				16		29.3			(0.4		)

States, municipalities and political subdivisions, tax-exempt	136			315.6				(1.8		)		80		174.3			(3.0		)

Corporate securities	1,802			3,213.30				(123.1		)		314		514.6			(43.2		)

Residential mortgage-backed securities	78			155				(1.0		)		186		398.3			(8.6		)

Commercial mortgage-backed securities	43			156.2				(0.6		)		10		33.2			(0.4		)

Other debt securities	79			270.6				(1.7		)		21		65			(1.6		)

Total fixed maturity securities	2,157			4,256.30				(128.5		)		629		1,215.60			(57.2		)

Equity securities	407			125.4				(11.1		)		—		—			—

Total fixed maturity and equity securities	2,564			$	4,381.70			$	(139.6	)		629		$	1,215.60		$	(57.2	)

The amortized cost and fair value of available-for-sale fixed maturity securities at March 31, 2015, 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	$	452.1			$	453.6

Due after one year through five years	4,730.20				4,804.30

Due after five years through ten years	5,159.30				5,338.60

Due after ten years	5,966.30				6,113.40

Mortgage-backed securities	2,548.90				2,624.10

Total available-for-sale fixed maturity securities	$	18,856.80			$	19,334.00

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, 2015 and 2014 are as follows:


	Three Months Ended
	March 31
	2015				2014
Proceeds	$	2,925.90			$	2,401.40

Gross realized gains	133.7				82.9

Gross realized losses	(87.2		)		(41.2		)
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, 2015
Fair Value Disclosures [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 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 pricing services may use quoted market prices of comparable instruments or discounted cash flow analyses, incorporating inputs that are currently observable in the markets for similar securities. We have controls in place to review the pricing services’ qualifications and procedures used to determine fair values. In addition, we periodically review the pricing services’ pricing methodologies, data sources and pricing inputs to ensure the fair values obtained are reasonable. Inputs that are often used in the valuation methodologies include, but are not limited to, broker quotes, benchmark yields, credit spreads, default rates and prepayment speeds. We also have certain fixed maturity securities, primarily corporate debt securities, 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, 2015 and December 31, 2014 is as follows:


		Level I			Level II				Level III			Total
	March 31, 2015
	Assets:
	Cash equivalents	$	665.7		$	—			$	—		$	665.7

	Investments available-for-sale:
	Fixed maturity securities:
	United States Government securities	379.7			—				—			379.7

	Government sponsored securities	—			114.6				—			114.6

	States, municipalities and political subdivisions, tax-exempt	—			5,817.20				—			5,817.20

	Corporate securities	7.1			9,519.90				165.5			9,692.50

	Options embedded in convertible debt securities	—			7				—			7

	Residential mortgage-backed securities	—			2,123.30				—			2,123.30

	Commercial mortgage-backed securities	—			497.6				3.2			500.8

	Other debt securities	64.1			632.2				2.6			698.9

	Total fixed maturity securities	450.9			18,711.80				171.3			19,334.00

	Equity securities	1,875.00			208.1				51.8			2,134.90

	Other invested assets, current	25.4			—				—			25.4

	Securities lending collateral	1,113.90			909.7				—			2,023.60

	Derivatives excluding embedded options (reported with other assets)	—			222.7				—			222.7

	Total assets	$	4,130.90		$	20,052.30			$	223.1		$	24,406.30

	Liabilities:
	Derivatives excluding embedded options (reported with other liabilities)	$	—		$	(224.6	)		$	—		$	(224.6	)

	Total liabilities	$	—		$	(224.6	)		$	—		$	(224.6	)


	December 31, 2014
	Assets:
	Cash equivalents	$	573.2		$	—			$	—		$	573.2

Investments available-for-sale:
Fixed maturity securities:
United States Government securities	320			—				—			320

Government sponsored securities	—			95				—			95

States, municipalities and political subdivisions, tax-exempt	—			5,733.60				—			5,733.60

Corporate securities	7.1			8,180.80				144.6			8,332.50

Options embedded in convertible debt securities	—			98.7				—			98.7

Residential mortgage-backed securities	—			2,159.00				—			2,159.00

Commercial mortgage-backed securities	—			506.6				3.3			509.9

Other debt securities	89.2			627.3				6.6			723.1

Total fixed maturity securities	416.3			17,401.00				154.5			17,971.80

Equity securities	1,696.90			192.9				48.3			1,938.10

Other invested assets, current	20.2			—				—			20.2

Securities lending collateral	808.3			706.9				—			1,515.20

Derivatives excluding embedded options (reported with other assets)	—			224.8				—			224.8

Total assets	$	3,514.90		$	18,525.60			$	202.8		$	22,243.30

Liabilities:
Derivatives excluding embedded options (reported with other liabilities)	$	—		$	(260.4	)		$	—		$	(260.4	)

Total liabilities	$	—		$	(260.4	)		$	—		$	(260.4	)




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, 2015 and 2014 is as follows:


	Corporate			Commercial				Other Debt			Equity				Long-term Receivable		Total
	Securities			Mortgage-				Securities			Securities
				backed
				Securities
Three Months Ended March 31, 2015

Beginning balance at January 1, 2015	$	144.6		$	3.3			$	6.6		$	48.3			$	—	$	202.8

Total gains (losses):
Recognized in net income	(0.2		)	—				0.2			(0.8		)		—		(0.8		)

Recognized in accumulated other comprehensive income	1.6			—				(0.2		)	1.3				—		2.7

Purchases	32.4			—				—			7.5				—		39.9

Sales	—			—				(0.9		)	(4.5		)		—		(5.4		)

Settlements	(13.6		)	(0.1		)		(0.1		)	—				—		(13.8		)

Transfers into Level III	0.7			—				—			—				—		0.7

Transfers out of Level III	—			—				(3.0		)	—				—		(3.0		)

Ending balance at March 31, 2015	$	165.5		$	3.2			$	2.6		$	51.8			$	—	$	223.1

Change in unrealized losses included in net income related to assets still held for the three months ended March 31, 2015	$	(0.6	)	$	—			$	—		$	(0.8	)		$	—	$	(1.4	)


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	)

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, 2015 or 2014.
Certain assets and liabilities are measured at fair value on a nonrecurring basis; that is, the instruments are not measured at fair value on an ongoing basis but are subject to fair value adjustments only in certain circumstances. As disclosed in Note 3, “Business Acquisition and Divestiture”, we completed our acquisition of Simply Healthcare on February 17, 2015. The values of net assets acquired in our acquisition of Simply Healthcare and resulting goodwill and other intangible assets were recorded at fair value primarily using Level III inputs. The majority of Simply Healthcare's assets acquired and liabilities assumed were recorded at their carrying values as of the respective date of acquisition, as their carrying values approximated their fair values due to their short-term nature. The fair values of goodwill and other intangible assets acquired in our acquisition of Simply Healthcare were internally estimated based on the income approach. The income approach estimates fair value based on the present value of the cash flows that the assets could be expected to generate in the future. We developed internal estimates for the expected cash flows and discount rate in the present value calculation. Other than the assets acquired and liabilities assumed in our acquisition of Simply Healthcare described above, there were no other assets or liabilities measured at fair value on a nonrecurring basis during the three months ended March 31, 2015 or 2014.
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 the pricing services to determine whether the prices are reasonable estimates of fair value. This analysis is performed by our internal treasury personnel who are familiar with our investment portfolios, the pricing services engaged and the valuation techniques and inputs used. Our analysis includes 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 the pricing services during the three months ended March 31, 2015 or 2014.
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 estimated to be available to us for debt of similar terms and remaining maturities.
Long-term debt – commercial paper: The carrying amount for commercial paper approximates fair value as the underlying instruments have variable interest rates at market value.
Long-term debt – 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 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, 2015 and December 31, 2014 are as follows:


	Carrying			Estimated Fair Value
	Value			Level I				Level II			Level III				Total
March 31, 2015
Assets:
Other invested assets, long-term	$	1,718.40		$	—			$	—		$	1,718.40			$	1,718.40

Liabilities:
Debt:
Short-term borrowings	450			—				450			—				450

Commercial paper	638.8			—				638.8			—				638.8

Notes	13,774.10			—				15,018.30			—				15,018.30

Convertible debentures	976.5			—				3,098.40			—				3,098.40


December 31, 2014
Assets:
Other invested assets, long-term	$	1,695.90		$	—			$	—		$	1,695.90			$	1,695.90

Liabilities:
Debt:
Short-term borrowings	400			—				400			—				400

Notes	13,777.80			—				14,794.80			—				14,794.80

Convertible debentures	974.4			—				2,581.90			—				2,581.90

Income_Taxes

Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	During the three months ended March 31, 2015 and 2014, we recognized income tax expense of $703.9 and $438.7, respectively, which represents effective tax rates of 44.9% and 38.8%, respectively. The increase in income tax expense was primarily due to increased income before income taxes and the increase to the non-tax deductible Health Insurance Provider Fee, or HIP Fee. For the three months ended March 31, 2015 and 2014, the HIP Fee resulted in additional income tax expense of $113.3 and $80.5, respectively. The increase was further impacted due to favorable 2014 discrete tax adjustments related to state income tax audits, including refund claims filed, and adjustments to state deferred tax liabilities in 2014 resulting from a decrease in the Indiana statutory income tax rate.
	The increase in the effective tax rate was primarily due to the increase to the non-tax deductible HIP Fee, the favorable 2014 discrete tax adjustments, and adjustments to the state deferred tax liabilities in 2014, discussed above.

Retirement_Benefits

Retirement Benefits	3 Months Ended
	Mar. 31, 2015
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, 2015 and 2014 are as follows:


		Pension Benefits						Other Benefits
		2015			2014			2015			2014
	Service cost	$	3.3		$	3.3		$	0.5		$	0.8

	Interest cost	17			18.5			5.9			6.6

	Expected return on assets	(35.7		)	(34.4		)	(5.9		)	(5.8		)
	Recognized actuarial loss	6.4			5.3			3.8			2.3

	Settlement loss	1.3			1.1			—			—

	Amortization of prior service credit	(0.2		)	(0.2		)	(3.6		)	(3.6		)
	Net periodic (credit) benefit cost	$	(7.9	)	$	(6.4	)	$	0.7		$	0.3

	For the year ending December 31, 2015, 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, 2015 or 2014.

Debt

Debt	3 Months Ended
	Mar. 31, 2015
Debt Instruments [Abstract]
Debt	Debt



	We generally issue senior unsecured notes for long-term borrowing purposes. At March 31, 2015, we had $13,749.2 outstanding under these notes. During the three months ended March 31, 2015, we purchased $13.0 of outstanding principal balance of certain senior unsecured notes, plus applicable premium for early redemption plus accrued and unpaid interest, for cash totaling $16.2. We recognized a loss on extinguishment of debt of $3.4 for the repurchase of these notes.
	We have an unsecured surplus note with an outstanding principal balance of $24.9 at March 31, 2015.
	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, 2015 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, 2015, we had $638.8 outstanding under this program.
	We have outstanding 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, 2015 the related balances, conversion rate and conversion price of the Debentures:


	Outstanding principal amount	$	1,500.00

	Unamortized debt discount	$	523.5

	Net debt carrying amount	$	976.5

	Equity component carrying amount	$	543.6

	Conversion rate (shares of common stock per $1,000 of principal amount)	13.3953

	Effective conversion price (per $1,000 of principal amount)	$	74.6524

	We have $450.0 in outstanding short-term borrowings from various Federal Home Loan Banks at March 31, 2015 with fixed interest rates of 0.194%.

Commitments_And_Contingencies

Commitments And Contingencies	3 Months Ended
Commitments And Contingencies	Mar. 31, 2015
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 Anthem Insurance. The lawsuit names Anthem Insurance as well as Anthem, Inc. and is captioned Ronald Gold, et al. v. Anthem, Inc. et al. Anthem Insurance’s 2001 Plan of Conversion, or the Plan, provided for the conversion of Anthem Insurance from a mutual insurance company into a stock insurance company pursuant to Indiana law. Under the Plan, Anthem Insurance 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 Anthem Insurance 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 Supreme 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. 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. On March 6, 2014, the trial court denied our motion for summary judgment finding that an issue of material fact existed. A trial on liability commenced on October 14, 2014 and concluded on October 16, 2014. The matter was taken under advisement by the trial court, which has requested post-trial briefing. We expect the trial court to issue its decision on liability sometime in 2015. 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. (n/k/a Anthem, 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, OON non-physician providers, the American Podiatric Medical Association, California Chiropractic Association and the California Psychological Association on behalf of putative classes of OON physicians and all OON 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 by using 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 subscriber 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 seeking 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 Anthem states except California. Following expert discovery and briefing, oral argument was held on the motion. In late 2014, the court denied the plaintiffs' motion for class certification in its entirety. The California subscriber plaintiffs filed a motion for leave to file a renewed motion for class certification with more narrowly defined proposed classes, which the court denied. 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 physician plaintiffs and certain medical association plaintiffs based on prior litigation releases, which was granted in 2011. The Florida Court ordered those 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 and some the medical associations did not dismiss their barred claims. The Florida Court found those enjoined plaintiffs in contempt and sanctioned them in July 2012. Those plaintiffs appealed the Florida Court’s sanctions order to the United States Court of Appeals for the Eleventh Circuit. The Eleventh Circuit upheld the Florida court’s enforcement of the injunction as it relates to the plaintiffs’ RICO and antitrust claims, but vacated it as it relates to certain ERISA claims. The plaintiffs filed a petition for rehearing en banc as to the antitrust claims only, which was denied. The plaintiffs then filed a petition for writ of certiorari with the U.S. Supreme Court. The American Medical Association filed an amicus brief in support of the petition. The U.S. Supreme Court denied the petition on February 23, 2015. We intend to vigorously defend these suits; however, their ultimate outcome cannot be presently determined.
	We are a defendant in multiple lawsuits that were initially filed in 2012 against the BCBSA as well as Blue Cross and/or Blue Shield licensees across the country. The cases were consolidated into a single multi-district lawsuit called In re Blue Cross Blue Shield Antitrust Litigation that is pending in the United States District Court for the Northern District of Alabama. Generally, the suits allege that the BCBSA and the Blue plans have engaged in a conspiracy to horizontally allocate geographic markets through license agreements, best efforts rules (which limit the percentage of non-Blue revenue of each plan), restrictions on acquisitions and other arrangements in violation of the Sherman Antitrust Act and related state laws. The cases were brought by two putative nationwide classes of plaintiffs, health plan subscribers and providers. Subscriber and provider plaintiffs each filed consolidated amended complaints on July 1, 2013. The consolidated amended subscriber complaint was also brought on behalf of putative state classes of health plan subscribers in Alabama, Arkansas, California, Florida, Hawaii, Illinois, Louisiana, Michigan, Mississippi, Missouri, New Hampshire, North Carolina, Pennsylvania, Rhode Island, South Carolina, Tennessee, and Texas. Defendants filed motions to dismiss in September 2013, which were argued in April 2014. In June 2014, the court denied the majority of the motions, ruling that plaintiffs had alleged sufficient facts at this stage of the litigation to avoid dismissal of their claims. Following the subsequent filing of amended complaints by each of the subscriber and provider plaintiffs, we filed our answer and asserted our affirmative defenses in December 2014. Discovery has commenced. 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, 2015. 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.
	Cyber Attack Incident
	In February 2015, we reported that we were the target of a sophisticated external cyber attack. The attackers gained unauthorized access to certain of our information technology systems and obtained personal information related to many individuals and employees, such as names, birthdays, health care identification/social security numbers, street addresses, email addresses, phone numbers and employment information, including income data. To date, there is no evidence that credit card or medical information, such as claims, test results or diagnostic codes, were targeted, accessed or obtained, although no assurance can be given that we will not identify additional information that was accessed or obtained.
	Currently, we are in the process of addressing the cyber attack and supporting federal law enforcement efforts to identify the responsible parties. Upon discovery of the cyber attack, we took immediate action to remediate the security vulnerability and retained a cybersecurity firm to evaluate our systems and identify solutions based on the evolving landscape. We will provide credit monitoring and identity protection services to those who have been affected by this cyber attack. While the cyber attack did not have an impact on our business, cash flows, financial condition and results of operations for the year ended December 31, 2014, we have incurred expenses subsequent to the cyber attack to investigate and remediate this matter and expect to continue to incur expenses of this nature in the foreseeable future. Although we are unable to quantify the ultimate magnitude of such expenses and any other impact to our business from this incident at this time, they may be significant. We will recognize these expenses in the periods in which they are incurred.
	Actions have been filed in various federal and state courts and other claims have been or may be asserted against us on behalf of current or former members, current or former employees, other individuals, shareholders or others seeking damages or other related relief, allegedly arising out of the cyber attack. State and federal agencies, including state insurance regulators, state attorneys general, the Health and Human Services Office of Civil Rights and the Federal Bureau of Investigations, are investigating events related to the cyber attack, including how it occurred, its consequences and our responses. Although we are cooperating in these investigations, we may be subject to fines or other obligations, which may have an adverse effect on how we operate our business and our results of operations. With respect to the civil actions, a motion to transfer was filed with the Judicial Panel on Multidistrict Litigation on February 10, 2015 and will be heard by the Panel on May 28, 2015.
	We have contingency plans and insurance coverage for certain expenses and potential liabilities of this nature, however, the coverage may not be sufficient to cover all claims and liabilities. While a loss from these matters is reasonably possible, we cannot reasonably estimate a range of possible losses because our investigation into the matter is ongoing, the proceedings remain in the early stages, alleged damages have not been specified, there is uncertainty as to the likelihood of a class or classes being certified or the ultimate size of any class if certified, and there are significant factual and legal issues to be resolved.
	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. Such associations, working together with NOLHGA, provide a safety net for their state’s policyholders, ensuring that they continue to receive coverage, subject to state maximum limits, 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. An initial plan was filed on April 30, 2013. The Insurance Commissioner filed an amended plan on August 8, 2014 and a second amended plan on October 8, 2014. The state court ordered a hearing to consider motions in response to and in connection with the second amended plan on May 11, 2015, which has been set for July 15, 2015. 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 held oral argument on the appeal in September 2014. 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, whereby Express Scripts is the exclusive provider of pharmacy benefit management, or PBM, services to our plans, excluding some Amerigroup subsidiaries and certain self-insured members, which have exclusive agreements with different PBM service providers. It is expected that those Amerigroup subsidiaries will complete their transition to the Express Scripts agreement during 2015. 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, 2015.
	During December 2014, we entered into a new 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, 2015 was $452.7 through March 31, 2020. 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, 2015 was $62.9 through March 31, 2016. We have the ability to terminate this agreement upon the occurrence of certain events, subject to early termination fees.
	Vulnerability from Concentrations
	Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash equivalents, investment securities, premium receivables and instruments held through hedging activities. All investment securities are managed by professional investment managers within policies authorized by our Board of Directors. Such policies limit the amounts that may be invested in any one issuer and prescribe certain investee company criteria. Concentrations of credit risk with respect to premium receivables are limited due to the large number of employer groups that constitute our customer base in the states in which we conduct business. As of March 31, 2015, there were no significant concentrations of financial instruments in a single investee, industry or geographic location.

Capital_Stock

Capital Stock	3 Months Ended
	Mar. 31, 2015
Capital [Abstract]
Capital Stock	Capital Stock
	Use of Capital – Dividends and Stock Repurchase Program
	We regularly review the appropriate use of capital, including acquisitions, common stock and debt security repurchases and dividends to shareholders. The declaration and payment of any dividends or repurchases of our common stock or debt is at the discretion of our Board of Directors and depends upon our financial condition, results of operations, future liquidity needs, regulatory and capital requirements and other factors deemed relevant by our Board of Directors.
	A summary of the cash dividend activity for the three months ended March 31, 2015 and 2014 is as follows:


	Declaration Date		Record Date		Payment Date		Cash	Total
							Dividend
							per Share
	Three Months Ended March 31, 2015
	January 27, 2015		March 10, 2015		March 25, 2015		$0.63	$166.60

	Three Months Ended March 31, 2014
	January 28, 2014		March 10, 2014		March 25, 2014		$0.44	$123.40
	Under our Board of Directors’ authorization, we maintain a common stock repurchase program. On October 2, 2014, the Board of Directors authorized a $5,000.0 increase to the common stock repurchase program. Repurchases may be made from time to time at prevailing market prices, subject to certain restrictions on volume, pricing and timing. The repurchases are effected from time to time in the open market, through negotiated transactions, including accelerated share repurchase agreements, and through plans designed to comply with Rule 10b5-1 under the Securities Exchange Act of 1934, as amended. Our stock repurchase program is discretionary as we are under no obligation to repurchase shares. We repurchase shares under the program when we believe it is a prudent use of capital. The excess cost of the repurchased shares over par value is charged on a pro rata basis to additional paid-in capital and retained earnings.
	A summary of common stock repurchases for the period April 1, 2015 through April 14, 2015 (subsequent to March 31, 2015) and for the three months ended March 31, 2015 and 2014 is as follows:


		April 1, 2015				Three Months Ended
		Through				March 31
		April 14, 2015				2015			2014
	Shares repurchased	0.5				5.7			14.3

	Average price per share	$	154.99			$	136.88		$	88.14

	Aggregate cost	$	79.9			$	774.1		$	1,262.80

	Authorization remaining at the end of each period	$	4,837.70			$	4,917.60		$	2,428.20

	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. In March 2014, we repurchased 6.6 shares under the agreement.
	In addition, during the three months ended March 31, 2015, we entered into a series of call and put options with certain counterparties to repurchase shares of our common stock below the then current market price. The Company exercised call options that enabled the repurchase of 1.8 shares of our common stock at an average strike price of $132.13. In order to set the call option strike prices below our market price at inception, we sold 4.2 put options at equal strike prices. During the three months ended March 31, 2015, 2.4 put options expired unexercised. The remaining 1.8 put options have expiration dates in September 2015. If the closing market price of our common stock on the expiration dates of the remaining put options is below the put option strike price, we will be required to repurchase up to 1.8 shares of our common stock at the higher contract price. Based on FASB guidance, the value of the call options was recognized as a reduction of shareholders' equity and the value of the put options was recognized as a liability.
	Subsequent to March 31, 2015, during April 2015 we bought call options for the repurchase of 0.4 shares of our common stock at an average strike price of $144.06 and sold put options for 1.0 shares of our common stock at equal strike prices. The call options expired in April 2015 while the put options expire in August 2015. If the closing market price of our common stock on the expiration dates of the put options is below the put option strike price, we will be required to repurchase up to 1.0 shares at the higher contract price.
	For additional information regarding the use of capital for debt security repurchases, see Note 8, “Debt.”
	Stock Incentive Plans
	A summary of stock option activity for the three months ended March 31, 2015 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, 2015	7.3			$	70.3

	Granted	1.2			146.93

	Exercised	(1.5	)		67.75

	Forfeited or expired	(0.1	)		77.92

	Outstanding at March 31, 2015	6.9			84.31			4.8		$	487

	Exercisable at March 31, 2015	4			66.61			2.92		$	352.1

	A summary of the status of nonvested restricted stock activity, including restricted stock units, for the three months ended March 31, 2015 is as follows:


		Restricted			Weighted-
		Stock Shares			Average
		and Units			Grant Date
					Fair Value
					per Share
	Nonvested at January 1, 2015	3.6			$	75.63

Granted	0.9			146.85

Vested	(1.5	)		72.13

Forfeited	—			—

Nonvested at March 31, 2015	3			98.64

Fair Value
We use a binomial lattice valuation model to estimate the fair value of all stock options granted. For a more detailed discussion of our stock incentive plan fair value methodology, see Note 14, “Capital Stock,” to our audited consolidated financial statements as of and for the year ended December 31, 2014 included in our 2014 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, 2015 and 2014:


	2015			2014
Risk-free interest rate	1.96	%		2.16	%
Volatility factor	31	%		35	%
Quarterly dividend yield	0.425	%		0.5	%
Weighted-average expected life (years)	4			3.75

The following weighted-average fair values were determined for the three months ended March 31, 2015 and 2014:


	2015				2014
Options granted during the period	$	33.95			$	22.2

Restricted stock awards granted during the period	146.85				89.43

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2015
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Accumulated Other Comprehensive Income	Accumulated Other Comprehensive Income
	A reconciliation of the components of accumulated other comprehensive income at March 31, 2015 and 2014 is as follows:


		2015				2014
	Investments:
	Gross unrealized gains	$	1,198.80			$	1,156.50

	Gross unrealized losses	(135.5		)		(161.8		)
	Net pre-tax unrealized gains	1,063.30				994.7

	Deferred tax liability	(375.3		)		(345.4		)
	Net unrealized gains on investments	688				649.3

	Non-credit components of other-than-temporary impairments on investments:
	Unrealized losses	(1.4		)		—

	Deferred tax asset	0.5				—

	Net unrealized non-credit component of other-than-temporary impairments on investments	(0.9		)		—

	Cash flow hedges:
	Gross unrealized losses	(53.8		)		(48.6		)
	Deferred tax asset	18.8				17

	Net unrealized losses on cash flow hedges	(35.0		)		(31.6		)
	Defined benefit pension plans:
	Deferred net actuarial loss	(556.1		)		(426.4		)
	Deferred prior service credits	2.1				8.4

	Deferred tax asset	220.3				167.5

	Net unrecognized periodic benefit costs for defined benefit pension plans	(333.7		)		(250.5		)
	Postretirement benefit plans:
	Deferred net actuarial loss	(194.8		)		(154.7		)
	Deferred prior service credits	71.8				86.2

	Deferred tax asset	48.8				27.4

	Net unrecognized periodic benefit costs for postretirement benefit plans	(74.2		)		(41.1		)
	Foreign currency translation adjustments:
	Gross unrealized (losses) gains	(9.7		)		2

	Deferred tax asset (liability)	3.4				(0.7		)

	Net unrealized (losses) gains on foreign currency translation adjustments	(6.3		)		1.3

	Accumulated other comprehensive income	$	237.9			$	327.4




	Other comprehensive income (loss) reclassification adjustments for the three months ended March 31, 2015 and 2014 are as follows:


		2015				2014
	Investments:
	Net holding gain on investment securities arising during the period, net of tax expense of ($33.4) and ($67.5), respectively	$	39.3			$	120.2

	Reclassification adjustment for net realized gain on investment securities, net of tax expense of ($11.4) and ($10.8), respectively	21.1				20.1

	Total reclassification adjustment on investments	60.4				140.3

	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 ($1.9) and ($0.3), respectively	3.5				0.5

Cash flow hedges:
Holding gain, net of tax expense of ($0.5) and ($0.4), respectively	0.9				0.7

Other:
Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, net of tax expense of ($3.0) and ($1.9), respectively	4.7				2.9

Foreign currency translation adjustment, net of tax benefit of $1.9 and $0.0, respectively	(3.5		)		(0.2		)
Net gain recognized in other comprehensive income, net of tax expense of ($48.3) and ($80.9), respectively	$	66			$	144.2

Earnings_Per_Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2015
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, 2015 and 2014 is as follows:


		Three Months Ended
		March 31
		2015	2014
	Denominator for basic earnings per share – weighted-average shares	266.6	284.9

	Effect of dilutive securities – employee stock options, non-vested restricted stock awards and convertible debentures	13.8	7.7

	Denominator for diluted earnings per share	280.4	292.6

	During the three months ended March 31, 2015 and 2014, weighted-average shares related to certain stock options of 0.4 and 0.6, 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, 2015, we issued approximately 0.9 restricted stock units under our stock incentive plans, 0.5 of which vesting is contingent upon us meeting specified annual earnings targets for the three year period of 2015 through 2017. 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 was 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 for the three months ended March 31, 2015 and 2014, respectively, and are included only if and when the contingency is met.

Segment_Information

Segment Information	3 Months Ended
	Mar. 31, 2015
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 19, “Segment Information,” to our audited consolidated financial statements as of and for the year ended December 31, 2014 included in our 2014 Annual Report on Form 10-K.
	Financial data by reportable segment for the three months ended March 31, 2015 and 2014 is as follows:


		Commercial			Government			Other			Total
		and Specialty			Business
		Business
	Three Months Ended March 31, 2015
	Operating revenue	$	9,366.90		$	9,480.10		$	4.4		$	18,851.40

	Operating gain (loss)	1,267.00			324.4			(12.1		)	1,579.30

	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

	A reconciliation of reportable segments operating revenues, a non-GAAP measure, to the amounts of total revenues included in the consolidated statements of income for the three months ended March 31, 2015 and 2014 is as follows:


		Three Months Ended
		March 31
		2015			2014
	Reportable segments operating revenues	$	18,851.40		$	17,644.80

	Net investment income	167.6			183.7

	Net realized gains on investments	46.5			41.7

	Other-than-temporary impairment losses recognized in income	(14.0		)	(10.8		)
	Total revenues	$	19,051.50		$	17,859.40

	A reconciliation of reportable segments operating gain, a non-GAAP measure, to income from continuing operations before income tax expense included in the consolidated statements of income for the three months ended March 31, 2015 and 2014 is as follows:


		Three Months Ended
		March 31
		2015			2014
	Reportable segments operating gain	$	1,579.30		$	1,118.70

	Net investment income	167.6			183.7

	Net realized gains on investments	46.5			41.7

	Other-than-temporary impairment losses recognized in income	(14.0		)	(10.8		)
	Interest expense	(154.4		)	(146.2		)
	Amortization of other intangible assets	(52.5		)	(54.0		)
	Loss on extinguishment of debt	(3.4		)	(3.0		)
	Income from continuing operations before income tax expense	$	1,569.10		$	1,130.10

Recovered_Sheet1

Basis of Presentation and Signficant Accounting Policies	3 Months Ended
Basis of Presentation and Signficant Accounting Policies	Mar. 31, 2015
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 2014 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, 2015 and 2014 have been recorded. The results of operations for the three months ended March 31, 2015 are not necessarily indicative of the results that may be expected for the full year ending December 31, 2015. These unaudited consolidated financial statements should be read in conjunction with our audited consolidated financial statements for the year ended December 31, 2014 included in our 2014 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.
Recent Accounting Guidance Not Yet Adopted	Recent Accounting Guidance Not Yet Adopted: In April 2015, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update No. 2015-05, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement, or ASU 2015-05. This amendment provides guidance to help entities determine whether a cloud computing arrangement contains a software license that should be accounted for as internal-use software or as a service contract. ASU 2015-05 is effective for interim and annual reporting periods beginning after December 15, 2015, with early adoption permitted. Upon adoption, an entity has the option to apply the provisions of ASU 2015-05 either prospectively to all arrangements entered into or materially modified, or retrospectively. We will evaluate the effects, if any, the adoption of ASU 2015-05 will have upon our consolidated financial position, results of operations or cash flows.
	In April 2015, the FASB issued Accounting Standards Update No. 2015-03, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs, or ASU 2015-03. ASU 2015-03 amends current presentation guidance by requiring that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. ASU 2015-03 is effective for interim and annual reporting periods beginning after December 15, 2015, with early adoption permitted. In accordance with GAAP guidance currently in effect, debt issuance costs are included within other current assets and other noncurrent assets in our consolidated balance sheets. The adoption of ASU 2015-03 will not impact our consolidated financial position, results of operations or cash flows.
	In February 2015, the FASB issued Accounting Standards Update No. 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis, or ASU 2015-02. ASU 2015-02 amends current consolidation guidance by modifying the evaluation of whether limited partnerships and similar legal entities are variable interest entities or voting interest entities, eliminating the presumption that a general partner should consolidate a limited partnership, and affects the consolidation analysis of reporting entities that are involved with variable interest entities. ASU No. 2015-02 is effective for interim and annual reporting periods beginning after December 15, 2015, with early adoption permitted. All legal entities are subject to reevaluation under the revised consolidation model. The adoption of ASU 2015-02 is not expected to have a material impact on our consolidated financial position, results of operations or cash flows.
	There were no other new accounting pronouncements that were issued or became effective since the issuance of our 2014 Annual Report on Form 10-K that had, or are expected to have, a material impact on our consolidated financial position, results of operations or cash flows.

Investments_Tables

Investments (Tables)	3 Months Ended
	Mar. 31, 2015
Investments [Abstract]
Current and Long-Term Investments, Available-For-Sale	A summary of current and long-term investments, available-for-sale, at March 31, 2015 and December 31, 2014 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, 2015
	Fixed maturity securities:
	United States Government securities	$	372.8			$	7			$	(0.1	)		$	—			$	379.7			$	—

	Government sponsored securities	113.6				1.2				—				(0.2		)		114.6				—

	States, municipalities and political subdivisions, tax-exempt	5,532.40				291.4				(5.0		)		(1.6		)		5,817.20				—

	Corporate securities	9,587.50				213.4				(76.5		)		(31.9		)		9,692.50				(1.4		)

	Options embedded in convertible debt securities	7				—				—				—				7				—

	Residential mortgage-backed securities	2,054.90				74.6				(1.6		)		(4.6		)		2,123.30				—

	Commercial mortgage-backed securities	494				7.2				(0.3		)		(0.1		)		500.8				—

	Other debt securities	694.6				6.3				(0.9		)		(1.1		)		698.9				—

	Total fixed maturity securities	18,856.80				601.1				(84.4		)		(39.5		)		19,334.00				$	(1.4	)

	Equity securities	1,548.80				597.7				(11.6		)		—				2,134.90

	Total investments, available-for-sale	$	20,405.60			$	1,198.80			$	(96.0	)		$	(39.5	)		$	21,468.90

	December 31, 2014
	Fixed maturity securities:
	United States Government securities	$	315.7			$	4.6			$	(0.3	)		$	—			$	320			$	—

	Government sponsored securities	94.6				0.8				—				(0.4		)		95				—

	States, municipalities and political subdivisions, tax-exempt	5,451.40				287				(1.8		)		(3.0		)		5,733.60				—

	Corporate securities	8,335.90				162.9				(123.1		)		(43.2		)		8,332.50				(6.8		)

	Options embedded in convertible debt securities	98.7				—				—				—				98.7				—

	Residential mortgage-backed securities	2,099.70				68.9				(1.0		)		(8.6		)		2,159.00				—

	Commercial mortgage-backed securities	504.8				6.1				(0.6		)		(0.4		)		509.9				—

	Other debt securities	720.3				6.1				(1.7		)		(1.6		)		723.1				—

	Total fixed maturity securities	17,621.10				536.4				(128.5		)		(57.2		)		17,971.80				$	(6.8	)

	Equity securities	1,330.70				618.5				(11.1		)		—				1,938.10

	Total investments, available-for-sale	$	18,951.80			$	1,154.90			$	(139.6	)		$	(57.2	)		$	19,909.90

Aggregate Fair Value and Gross Unrealized Loss of Fixed Maturity Securities and Equity Securities in an Unrealized Loss Position	The following tables summarize for available-for-sale fixed maturity securities and available-for-sale equity securities in an unrealized loss position at March 31, 2015 and December 31, 2014, 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, 2015
	Fixed maturity securities:
	United States Government securities	10			$	48.5			$	(0.1	)		2			$	0.9			$	—

	Government sponsored securities	5			5.3				—				10			21.4				(0.2		)

	States, municipalities and political subdivisions, tax-exempt	161			427.3				(5.0		)		36			58.1				(1.6		)

	Corporate securities	906			2,093.10				(76.5		)		256			360.7				(31.9		)

	Residential mortgage-backed securities	105			224.7				(1.6		)		118			210.5				(4.6		)

	Commercial mortgage-backed securities	26			99.9				(0.3		)		8			30.5				(0.1		)

	Other debt securities	61			211.7				(0.9		)		18			52.2				(1.1		)

	Total fixed maturity securities	1,274			3,110.50				(84.4		)		448			734.3				(39.5		)

	Equity securities	445			232.3				(11.6		)		—			—				—

	Total fixed maturity and equity securities	1,719			$	3,342.80			$	(96.0	)		448			$	734.3			$	(39.5	)

	31-Dec-14
	Fixed maturity securities:
	United States Government securities	17			$	145.3			$	(0.3	)		2			$	0.9			$	—

	Government sponsored securities	2			0.3				—				16			29.3				(0.4		)

	States, municipalities and political subdivisions, tax-exempt	136			315.6				(1.8		)		80			174.3				(3.0		)

	Corporate securities	1,802			3,213.30				(123.1		)		314			514.6				(43.2		)

	Residential mortgage-backed securities	78			155				(1.0		)		186			398.3				(8.6		)

	Commercial mortgage-backed securities	43			156.2				(0.6		)		10			33.2				(0.4		)

	Other debt securities	79			270.6				(1.7		)		21			65				(1.6		)

	Total fixed maturity securities	2,157			4,256.30				(128.5		)		629			1,215.60				(57.2		)

	Equity securities	407			125.4				(11.1		)		—			—				—

	Total fixed maturity and equity securities	2,564			$	4,381.70			$	(139.6	)		629			$	1,215.60			$	(57.2	)

Amortized Cost and Fair Value of Fixed Maturity Securities, By Contractual Maturity	The amortized cost and fair value of available-for-sale fixed maturity securities at March 31, 2015, 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	$	452.1			$	453.6

	Due after one year through five years	4,730.20				4,804.30

	Due after five years through ten years	5,159.30				5,338.60

	Due after ten years	5,966.30				6,113.40

	Mortgage-backed securities	2,548.90				2,624.10

	Total available-for-sale fixed maturity securities	$	18,856.80			$	19,334.00

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, 2015 and 2014 are as follows:


		Three Months Ended
		March 31
		2015				2014
	Proceeds	$	2,925.90			$	2,401.40

	Gross realized gains	133.7				82.9

	Gross realized losses	(87.2		)		(41.2		)

Fair_Value_Tables

Fair Value (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements By Level For Assets Measured At Fair Value On A Recurring Basis	A summary of fair value measurements by level for assets and liabilities measured at fair value on a recurring basis at March 31, 2015 and December 31, 2014 is as follows:


		Level I				Level II				Level III				Total
	March 31, 2015
	Assets:
	Cash equivalents	$	665.7			$	—			$	—			$	665.7

	Investments available-for-sale:
	Fixed maturity securities:
	United States Government securities	379.7				—				—				379.7

	Government sponsored securities	—				114.6				—				114.6

	States, municipalities and political subdivisions, tax-exempt	—				5,817.20				—				5,817.20

	Corporate securities	7.1				9,519.90				165.5				9,692.50

	Options embedded in convertible debt securities	—				7				—				7

	Residential mortgage-backed securities	—				2,123.30				—				2,123.30

	Commercial mortgage-backed securities	—				497.6				3.2				500.8

	Other debt securities	64.1				632.2				2.6				698.9

	Total fixed maturity securities	450.9				18,711.80				171.3				19,334.00

	Equity securities	1,875.00				208.1				51.8				2,134.90

	Other invested assets, current	25.4				—				—				25.4

	Securities lending collateral	1,113.90				909.7				—				2,023.60

	Derivatives excluding embedded options (reported with other assets)	—				222.7				—				222.7

	Total assets	$	4,130.90			$	20,052.30			$	223.1			$	24,406.30

	Liabilities:
	Derivatives excluding embedded options (reported with other liabilities)	$	—			$	(224.6	)		$	—			$	(224.6	)

	Total liabilities	$	—			$	(224.6	)		$	—			$	(224.6	)


	December 31, 2014
	Assets:
	Cash equivalents	$	573.2			$	—			$	—			$	573.2

	Investments available-for-sale:
	Fixed maturity securities:
	United States Government securities	320				—				—				320

	Government sponsored securities	—				95				—				95

	States, municipalities and political subdivisions, tax-exempt	—				5,733.60				—				5,733.60

	Corporate securities	7.1				8,180.80				144.6				8,332.50

	Options embedded in convertible debt securities	—				98.7				—				98.7

	Residential mortgage-backed securities	—				2,159.00				—				2,159.00

	Commercial mortgage-backed securities	—				506.6				3.3				509.9

Other debt securities	89.2				627.3				6.6				723.1

Total fixed maturity securities	416.3				17,401.00				154.5				17,971.80

Equity securities	1,696.90				192.9				48.3				1,938.10

Other invested assets, current	20.2				—				—				20.2

Securities lending collateral	808.3				706.9				—				1,515.20

Derivatives excluding embedded options (reported with other assets)	—				224.8				—				224.8

Total assets	$	3,514.90			$	18,525.60			$	202.8			$	22,243.30

Liabilities:
Derivatives excluding embedded options (reported with other liabilities)	$	—			$	(260.4	)		$	—			$	(260.4	)

Total liabilities	$	—			$	(260.4	)		$	—			$	(260.4	)

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, 2015 and 2014 is as follows:


		Corporate				Commercial				Other Debt				Equity			Long-term Receivable		Total
		Securities				Mortgage-				Securities				Securities
						backed
						Securities
	Three Months Ended March 31, 2015

	Beginning balance at January 1, 2015	$	144.6			$	3.3			$	6.6			$	48.3		$	—	$	202.8

	Total gains (losses):
	Recognized in net income	(0.2		)		—				0.2				(0.8		)	—		(0.8		)

	Recognized in accumulated other comprehensive income	1.6				—				(0.2		)		1.3			—		2.7

	Purchases	32.4				—				—				7.5			—		39.9

	Sales	—				—				(0.9		)		(4.5		)	—		(5.4		)

	Settlements	(13.6		)		(0.1		)		(0.1		)		—			—		(13.8		)

	Transfers into Level III	0.7				—				—				—			—		0.7

	Transfers out of Level III	—				—				(3.0		)		—			—		(3.0		)

	Ending balance at March 31, 2015	$	165.5			$	3.2			$	2.6			$	51.8		$	—	$	223.1

	Change in unrealized losses included in net income related to assets still held for the three months ended March 31, 2015	$	(0.6	)		$	—			$	—			$	(0.8	)	$	—	$	(1.4	)


	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	)

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, 2015 and December 31, 2014 are as follows:


		Carrying				Estimated Fair Value
		Value				Level I				Level II				Level III			Total
	March 31, 2015
	Assets:
	Other invested assets, long-term	$	1,718.40			$	—			$	—			$	1,718.40		$	1,718.40

	Liabilities:
	Debt:
	Short-term borrowings	450				—				450				—			450

	Commercial paper	638.8				—				638.8				—			638.8

	Notes	13,774.10				—				15,018.30				—			15,018.30

	Convertible debentures	976.5				—				3,098.40				—			3,098.40


	December 31, 2014
	Assets:
	Other invested assets, long-term	$	1,695.90			$	—			$	—			$	1,695.90		$	1,695.90

	Liabilities:
	Debt:
	Short-term borrowings	400				—				400				—			400

	Notes	13,777.80				—				14,794.80				—			14,794.80

	Convertible debentures	974.4				—				2,581.90				—			2,581.90

Retirement_Benefits_Tables

Retirement Benefits (Tables)	3 Months Ended
	Mar. 31, 2015
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, 2015 and 2014 are as follows:


		Pension Benefits						Other Benefits
		2015			2014			2015			2014
	Service cost	$	3.3		$	3.3		$	0.5		$	0.8

	Interest cost	17			18.5			5.9			6.6

	Expected return on assets	(35.7		)	(34.4		)	(5.9		)	(5.8		)
	Recognized actuarial loss	6.4			5.3			3.8			2.3

	Settlement loss	1.3			1.1			—			—

	Amortization of prior service credit	(0.2		)	(0.2		)	(3.6		)	(3.6		)
	Net periodic (credit) benefit cost	$	(7.9	)	$	(6.4	)	$	0.7		$	0.3

Debt_Tables

Debt (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Instruments [Abstract]
Convertible Debenture Terms	The following table summarizes at March 31, 2015 the related balances, conversion rate and conversion price of the Debentures:


	Outstanding principal amount	$	1,500.00

	Unamortized debt discount	$	523.5

	Net debt carrying amount	$	976.5

	Equity component carrying amount	$	543.6

	Conversion rate (shares of common stock per $1,000 of principal amount)	13.3953

	Effective conversion price (per $1,000 of principal amount)	$	74.6524

Capital_Stock_Tables

Capital Stock (Tables)	3 Months Ended
	Mar. 31, 2015
Capital [Abstract]
Summary of Cash Dividend Activity	A summary of the cash dividend activity for the three months ended March 31, 2015 and 2014 is as follows:


	Declaration Date		Record Date	Payment Date		Cash	Total
						Dividend
						per Share
	Three Months Ended March 31, 2015
	January 27, 2015		March 10, 2015	March 25, 2015		$0.63	$166.60

	Three Months Ended March 31, 2014
	January 28, 2014		March 10, 2014	March 25, 2014		$0.44	$123.40
Summary of Share Repurchases	A summary of common stock repurchases for the period April 1, 2015 through April 14, 2015 (subsequent to March 31, 2015) and for the three months ended March 31, 2015 and 2014 is as follows:


		April 1, 2015			Three Months Ended
		Through			March 31
		April 14, 2015			2015			2014
	Shares repurchased	0.5			5.7			14.3

	Average price per share	$	154.99		$	136.88		$	88.14

	Aggregate cost	$	79.9		$	774.1		$	1,262.80

	Authorization remaining at the end of each period	$	4,837.70		$	4,917.60		$	2,428.20

Summary of Stock Option Activity	A summary of stock option activity for the three months ended March 31, 2015 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, 2015	7.3		$	70.3

	Granted	1.2		146.93

	Exercised	(1.5	)	67.75

	Forfeited or expired	(0.1	)	77.92

	Outstanding at March 31, 2015	6.9		84.31			4.8		$	487

	Exercisable at March 31, 2015	4		66.61			2.92		$	352.1

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, 2015 is as follows:


		Restricted		Weighted-
		Stock Shares		Average
		and Units		Grant Date
				Fair Value
				per Share
	Nonvested at January 1, 2015	3.6		$	75.63

	Granted	0.9		146.85

	Vested	(1.5	)	72.13

	Forfeited	—		—

	Nonvested at March 31, 2015	3		98.64

Summary of Weighted-Average Assumptions Used to Estimate the Fair Value of Options Granted During the Periods	The following weighted-average assumptions were used to estimate the fair values of options granted during the three months ended March 31, 2015 and 2014:


		2015		2014
	Risk-free interest rate	1.96	%	2.16	%
	Volatility factor	31	%	35	%
	Quarterly dividend yield	0.425	%	0.5	%
	Weighted-average expected life (years)	4		3.75

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, 2015 and 2014:


		2015			2014
	Options granted during the period	$	33.95		$	22.2

	Restricted stock awards granted during the period	146.85			89.43

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2015
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Components Of Accumulated Other Comprehensive Income	A reconciliation of the components of accumulated other comprehensive income at March 31, 2015 and 2014 is as follows:


		2015			2014
	Investments:
	Gross unrealized gains	$	1,198.80		$	1,156.50

	Gross unrealized losses	(135.5		)	(161.8		)
	Net pre-tax unrealized gains	1,063.30			994.7

	Deferred tax liability	(375.3		)	(345.4		)
	Net unrealized gains on investments	688			649.3

	Non-credit components of other-than-temporary impairments on investments:
	Unrealized losses	(1.4		)	—

	Deferred tax asset	0.5			—

	Net unrealized non-credit component of other-than-temporary impairments on investments	(0.9		)	—

	Cash flow hedges:
	Gross unrealized losses	(53.8		)	(48.6		)
	Deferred tax asset	18.8			17

	Net unrealized losses on cash flow hedges	(35.0		)	(31.6		)
	Defined benefit pension plans:
	Deferred net actuarial loss	(556.1		)	(426.4		)
	Deferred prior service credits	2.1			8.4

	Deferred tax asset	220.3			167.5

	Net unrecognized periodic benefit costs for defined benefit pension plans	(333.7		)	(250.5		)
	Postretirement benefit plans:
	Deferred net actuarial loss	(194.8		)	(154.7		)
	Deferred prior service credits	71.8			86.2

	Deferred tax asset	48.8			27.4

	Net unrecognized periodic benefit costs for postretirement benefit plans	(74.2		)	(41.1		)
	Foreign currency translation adjustments:
	Gross unrealized (losses) gains	(9.7		)	2

	Deferred tax asset (liability)	3.4			(0.7		)

	Net unrealized (losses) gains on foreign currency translation adjustments	(6.3		)	1.3

	Accumulated other comprehensive income	$	237.9		$	327.4

Other Comprehensive Income Reclassification Adjustments


	Other comprehensive income (loss) reclassification adjustments for the three months ended March 31, 2015 and 2014 are as follows:


		2015			2014
	Investments:
	Net holding gain on investment securities arising during the period, net of tax expense of ($33.4) and ($67.5), respectively	$	39.3		$	120.2

	Reclassification adjustment for net realized gain on investment securities, net of tax expense of ($11.4) and ($10.8), respectively	21.1			20.1

	Total reclassification adjustment on investments	60.4			140.3

	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 ($1.9) and ($0.3), respectively	3.5			0.5

	Cash flow hedges:
	Holding gain, net of tax expense of ($0.5) and ($0.4), respectively	0.9			0.7

	Other:
	Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, net of tax expense of ($3.0) and ($1.9), respectively	4.7			2.9

	Foreign currency translation adjustment, net of tax benefit of $1.9 and $0.0, respectively	(3.5		)	(0.2		)
	Net gain recognized in other comprehensive income, net of tax expense of ($48.3) and ($80.9), respectively	$	66		$	144.2

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2015
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, 2015 and 2014 is as follows:


		Three Months Ended
		March 31
		2015	2014
	Denominator for basic earnings per share – weighted-average shares	266.6	284.9

	Effect of dilutive securities – employee stock options, non-vested restricted stock awards and convertible debentures	13.8	7.7

	Denominator for diluted earnings per share	280.4	292.6

Segment_Information_Tables

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Financial Data By Reportable Segment	Financial data by reportable segment for the three months ended March 31, 2015 and 2014 is as follows:


		Commercial			Government			Other			Total
		and Specialty			Business
		Business
	Three Months Ended March 31, 2015
	Operating revenue	$	9,366.90		$	9,480.10		$	4.4		$	18,851.40

	Operating gain (loss)	1,267.00			324.4			(12.1		)	1,579.30

	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

Reconciliation Of Reportable Segments Operating Revenues To Total Revenues Reported In The Consolidated Statements Of Income	A reconciliation of reportable segments operating revenues, a non-GAAP measure, to the amounts of total revenues included in the consolidated statements of income for the three months ended March 31, 2015 and 2014 is as follows:


		Three Months Ended
		March 31
		2015			2014
	Reportable segments operating revenues	$	18,851.40		$	17,644.80

	Net investment income	167.6			183.7

	Net realized gains on investments	46.5			41.7

	Other-than-temporary impairment losses recognized in income	(14.0		)	(10.8		)
	Total revenues	$	19,051.50		$	17,859.40

Reconciliation Of Reportable Segments Operating Gain To Income Before Income Tax Expense Included In The Consolidated Statements Of Income	A reconciliation of reportable segments operating gain, a non-GAAP measure, to income from continuing operations before income tax expense included in the consolidated statements of income for the three months ended March 31, 2015 and 2014 is as follows:


		Three Months Ended
		March 31
		2015			2014
	Reportable segments operating gain	$	1,579.30		$	1,118.70

	Net investment income	167.6			183.7

	Net realized gains on investments	46.5			41.7

	Other-than-temporary impairment losses recognized in income	(14.0		)	(10.8		)
	Interest expense	(154.4		)	(146.2		)
	Amortization of other intangible assets	(52.5		)	(54.0		)
	Loss on extinguishment of debt	(3.4		)	(3.0		)
	Income from continuing operations before income tax expense	$	1,569.10		$	1,130.10

Organization_Details

Organization (Details)	Mar. 31, 2015
	states
	county
	medical_member
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of medical membership members	38,500,000
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

Business_Acquisition_and_Dives1

Business Acquisition and Divestiture Business Acquisition and Divestiture (Assets Liabilities Acquired) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill	17,570.90	$17,082
Simply Healthcare [Member] \| Government Business [Member]
Business Acquisition [Line Items]
Other Intangible Assets	388
Goodwill	488.9
Customer Relationships [Member] \| Simply Healthcare [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	3 years 0 months 0 days
Customer Relationships [Member] \| Simply Healthcare [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	4 years 0 months 0 days

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, 2015	Mar. 31, 2014	Dec. 31, 2014
Investments [Line Items]
Cost or Amortized Cost	$20,405.60		$18,951.80
Gross Unrealized Gains	1,198.80	1,156.50	1,154.90
Gross unrealized loss, less than 12 months	-96		-139.6
Gross unrealized loss, 12 months or greater	-39.5		-57.2
Estimated Fair Value	21,468.90		19,909.90
Equity Securities [Member]
Investments [Line Items]
Cost or Amortized Cost	1,548.80		1,330.70
Gross Unrealized Gains	597.7		618.5
Gross unrealized loss, less than 12 months	-11.6		-11.1
Gross unrealized loss, 12 months or greater	0		0
Estimated Fair Value	2,134.90		1,938.10
Fixed Maturities [Member]
Investments [Line Items]
Cost or Amortized Cost	18,856.80		17,621.10
Gross Unrealized Gains	601.1		536.4
Gross unrealized loss, less than 12 months	-84.4		-128.5
Gross unrealized loss, 12 months or greater	-39.5		-57.2
Estimated Fair Value	19,334		17,971.80
Non-Credit Component of Other-Than-Temporary Impairments Recognized in Accumulated Other Comprehensive Income	-1.4		-6.8
Fixed Maturities [Member] \| United States Government Securities [Member]
Investments [Line Items]
Cost or Amortized Cost	372.8		315.7
Gross Unrealized Gains	7		4.6
Gross unrealized loss, less than 12 months	-0.1		-0.3
Gross unrealized loss, 12 months or greater	0		0
Estimated Fair Value	379.7		320
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	113.6		94.6
Gross Unrealized Gains	1.2		0.8
Gross unrealized loss, less than 12 months	0		0
Gross unrealized loss, 12 months or greater	-0.2		-0.4
Estimated Fair Value	114.6		95
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	5,532.40		5,451.40
Gross Unrealized Gains	291.4		287
Gross unrealized loss, less than 12 months	-5		-1.8
Gross unrealized loss, 12 months or greater	-1.6		-3
Estimated Fair Value	5,817.20		5,733.60
Non-Credit Component of Other-Than-Temporary Impairments Recognized in Accumulated Other Comprehensive Income	0		0
Fixed Maturities [Member] \| Corporate Securities [Member]
Investments [Line Items]
Cost or Amortized Cost	9,587.50		8,335.90
Gross Unrealized Gains	213.4		162.9
Gross unrealized loss, less than 12 months	-76.5		-123.1
Gross unrealized loss, 12 months or greater	-31.9		-43.2
Estimated Fair Value	9,692.50		8,332.50
Non-Credit Component of Other-Than-Temporary Impairments Recognized in Accumulated Other Comprehensive Income	-1.4		-6.8
Fixed Maturities [Member] \| Options Embedded In Convertible Debt Securities [Member]
Investments [Line Items]
Cost or Amortized Cost	7		98.7
Gross Unrealized Gains	0		0
Gross unrealized loss, less than 12 months	0		0
Gross unrealized loss, 12 months or greater	0		0
Estimated Fair Value	7		98.7
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	2,054.90		2,099.70
Gross Unrealized Gains	74.6		68.9
Gross unrealized loss, less than 12 months	-1.6		-1
Gross unrealized loss, 12 months or greater	-4.6		-8.6
Estimated Fair Value	2,123.30		2,159
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	494		504.8
Gross Unrealized Gains	7.2		6.1
Gross unrealized loss, less than 12 months	-0.3		-0.6
Gross unrealized loss, 12 months or greater	-0.1		-0.4
Estimated Fair Value	500.8		509.9
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	694.6		720.3
Gross Unrealized Gains	6.3		6.1
Gross unrealized loss, less than 12 months	-0.9		-1.7
Gross unrealized loss, 12 months or greater	-1.1		-1.6
Estimated Fair Value	698.9		723.1
Non-Credit Component of Other-Than-Temporary Impairments Recognized in Accumulated Other Comprehensive Income	$0		$0

Investments_Aggregate_Fair_Val

Investments (Aggregate Fair Value And Gross Unrealized Loss Of Fixed Maturity Securities And Equity Securities In An Unrealized Loss Position) (Details) (USD $)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
	securities	securities
Schedule of Investments [Line Items]
Number of securities, less than 12 months	1,719	2,564
Estimated fair value, less than 12 months	$3,342.80	$4,381.70
Gross unrealized loss, less than 12 months	-96	-139.6
Number of securities, 12 months or greater	448	629
Estimated fair value, 12 months or greater	734.3	1,215.60
Gross unrealized loss, 12 months or greater	-39.5	-57.2
Equity Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months	445	407
Estimated fair value, less than 12 months	232.3	125.4
Gross unrealized loss, less than 12 months	-11.6	-11.1
Number of securities, 12 months or greater	0	0
Estimated fair value, 12 months or greater	0	0
Gross unrealized loss, 12 months or greater	0	0
Fixed Maturities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months	1,274	2,157
Estimated fair value, less than 12 months	3,110.50	4,256.30
Gross unrealized loss, less than 12 months	-84.4	-128.5
Number of securities, 12 months or greater	448	629
Estimated fair value, 12 months or greater	734.3	1,215.60
Gross unrealized loss, 12 months or greater	-39.5	-57.2
Fixed Maturities [Member] \| United States Government Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months	10	17
Estimated fair value, less than 12 months	48.5	145.3
Gross unrealized loss, less than 12 months	-0.1	-0.3
Number of securities, 12 months or greater	2	2
Estimated fair value, 12 months or greater	0.9	0.9
Gross unrealized loss, 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	5	2
Estimated fair value, less than 12 months	5.3	0.3
Gross unrealized loss, less than 12 months	0	0
Number of securities, 12 months or greater	10	16
Estimated fair value, 12 months or greater	21.4	29.3
Gross unrealized loss, 12 months or greater	-0.2	-0.4
Fixed Maturities [Member] \| States, Municipalities And Political Subdivisions, Tax-Exempt [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months	161	136
Estimated fair value, less than 12 months	427.3	315.6
Gross unrealized loss, less than 12 months	-5	-1.8
Number of securities, 12 months or greater	36	80
Estimated fair value, 12 months or greater	58.1	174.3
Gross unrealized loss, 12 months or greater	-1.6	-3
Fixed Maturities [Member] \| Corporate Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months	906	1,802
Estimated fair value, less than 12 months	2,093.10	3,213.30
Gross unrealized loss, less than 12 months	-76.5	-123.1
Number of securities, 12 months or greater	256	314
Estimated fair value, 12 months or greater	360.7	514.6
Gross unrealized loss, 12 months or greater	-31.9	-43.2
Fixed Maturities [Member] \| Residential Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months	105	78
Estimated fair value, less than 12 months	224.7	155
Gross unrealized loss, less than 12 months	-1.6	-1
Number of securities, 12 months or greater	118	186
Estimated fair value, 12 months or greater	210.5	398.3
Gross unrealized loss, 12 months or greater	-4.6	-8.6
Fixed Maturities [Member] \| Commercial Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months	26	43
Estimated fair value, less than 12 months	99.9	156.2
Gross unrealized loss, less than 12 months	-0.3	-0.6
Number of securities, 12 months or greater	8	10
Estimated fair value, 12 months or greater	30.5	33.2
Gross unrealized loss, 12 months or greater	-0.1	-0.4
Fixed Maturities [Member] \| Other Debt Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months	61	79
Estimated fair value, less than 12 months	211.7	270.6
Gross unrealized loss, less than 12 months	-0.9	-1.7
Number of securities, 12 months or greater	18	21
Estimated fair value, 12 months or greater	52.2	65
Gross unrealized loss, 12 months or greater	($1.10)	($1.60)

Investments_Amortized_Cost_And

Investments (Amortized Cost And Fair Value Of Fixed Maturity Securities, By Contractual Maturity) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Investments [Line Items]
Available-for-sale securities, Amortized Cost	$20,405.60	$18,951.80
Available-for-sale securities, Estimated Fair Value	21,468.90	19,909.90
Fixed Maturities [Member]
Schedule of Investments [Line Items]
Due in one year or less, Amortized Cost	452.1
Due after one year through five years, Amortized Cost	4,730.20
Due after five years through ten years, Amortized Cost	5,159.30
Due after ten years, Amortized Cost	5,966.30
Mortgage-backed securities, Amortized Cost	2,548.90
Available-for-sale securities, Amortized Cost	18,856.80	17,621.10
Due in one year or less, Estimated Fair Value	453.6
Due after one year through five years, Estimated Fair Value	4,804.30
Due after five years through ten years, Estimated Fair Value	5,338.60
Due after ten years, Estimated Fair Value	6,113.40
Mortgage-backed securities, Estimated Fair Value	2,624.10
Available-for-sale securities, Estimated Fair Value	$19,334	$17,971.80

Investments_Proceeds_and_Reali

Investments (Proceeds and Realized Gains Losses From Investments) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Investments [Abstract]
Proceeds	$2,925.90	$2,401.40
Gross realized gains	133.7	82.9
Gross realized losses	($87.20)	($41.20)

Investments_Narrative_Details

Investments (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Schedule of Investments [Line Items]
Available-for-sale Securities	$21,468.90		$19,909.90
Other-than-temporary impairment losses recognized in income	14	10.8
Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities	2,624.10
Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities	634.7
Sub-Prime Mortgage-Backed and Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities	36.1
Unrealized Gain (Loss) on Securities	1.4
Alt-A Mortgage-Backed and Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities	73.1
Unrealized Gain (Loss) on Securities	$4.70

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, 2015	Dec. 31, 2014
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$665.70	$573.20
Fair value assets measured on recurring basis available-for-sale securities	21,468.90	19,909.90
Other invested assets, current	25.4	20.2
Securities lending collateral	2,023.60	1,515.20
Total assets	24,406.30	22,243.30
Total liabilities	-224.6	-260.4
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	19,334	17,971.80
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	379.7	320
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	114.6	95
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	5,817.20	5,733.60
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	9,692.50	8,332.50
Fixed Maturities [Member] \| Embedded Derivative Financial Instruments [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	7	98.7
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	2,123.30	2,159
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	500.8	509.9
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	698.9	723.1
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	2,134.90	1,938.10
Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, current	25.4	20.2
Derivatives Excluding Embedded Options [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives excluding embedded options (reported with other assets)	222.7	224.8
Derivatives excluding embedded options (reported with other liabilities)	-224.6	-260.4
Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	665.7	573.2
Securities lending collateral	1,113.90	808.3
Total assets	4,130.90	3,514.90
Total liabilities	0	0
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	450.9	416.3
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	379.7	320
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	7.1	7.1
Level I [Member] \| Fixed Maturities [Member] \| Embedded Derivative Financial Instruments [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	64.1	89.2
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	1,875	1,696.90
Level I [Member] \| Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, current	25.4	20.2
Level I [Member] \| Derivatives Excluding Embedded Options [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 II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Securities lending collateral	909.7	706.9
Total assets	20,052.30	18,525.60
Total liabilities	-224.6	-260.4
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	18,711.80	17,401
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	114.6	95
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	5,817.20	5,733.60
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	9,519.90	8,180.80
Level II [Member] \| Fixed Maturities [Member] \| Embedded Derivative Financial Instruments [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	7	98.7
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	2,123.30	2,159
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	497.6	506.6
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	632.2	627.3
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	208.1	192.9
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] \| Derivatives Excluding Embedded Options [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives excluding embedded options (reported with other assets)	222.7	224.8
Derivatives excluding embedded options (reported with other liabilities)	-224.6	-260.4
Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Securities lending collateral	0	0
Total assets	223.1	202.8
Total liabilities	0	0
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	171.3	154.5
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	165.5	144.6
Level III [Member] \| Fixed Maturities [Member] \| Embedded Derivative Financial Instruments [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	3.2	3.3
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	2.6	6.6
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	51.8	48.3
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] \| Derivatives Excluding Embedded Options [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

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, 2015	Mar. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$202.80	$177.90
Total gains (losses) recognized in net income	-0.8	18
Total gains (losses) recognized in accumulated other comprehensive income	2.7	-2.5
Purchases	39.9	18.3
Sales	-5.4	-2.8
Settlements	-13.8	-5.7
Transfers into Level III	0.7	0
Transfers out of Level III	-3	-6.5
Ending balance	223.1	196.7
Change in unrealized losses included in net income related to assets still held	-1.4	-4.3
Corporate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	144.6	115.2
Total gains (losses) recognized in net income	-0.2	-3.3
Total gains (losses) recognized in accumulated other comprehensive income	1.6	3.1
Purchases	32.4	9.3
Sales	0	-1.7
Settlements	-13.6	-2.1
Transfers into Level III	0.7	0
Transfers out of Level III	0	-6.5
Ending balance	165.5	114
Change in unrealized losses included in net income related to assets still held	-0.6	-4
Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	3.3	6.5
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	-3.4
Transfers into Level III	0	0
Transfers out of Level III	0	0
Ending balance	3.2	3.1
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	6.6	14.8
Total gains (losses) recognized in net income	0.2	0
Total gains (losses) recognized in accumulated other comprehensive income	-0.2	0.2
Purchases	0	0
Sales	-0.9	0
Settlements	-0.1	-0.2
Transfers into Level III	0	0
Transfers out of Level III	-3	0
Ending balance	2.6	14.8
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	48.3	41.4
Total gains (losses) recognized in net income	-0.8	-0.3
Total gains (losses) recognized in accumulated other comprehensive income	1.3	-5.8
Purchases	7.5	9
Sales	-4.5	-1.1
Settlements	0	0
Transfers into Level III	0	0
Transfers out of Level III	0	0
Ending balance	51.8	43.2
Change in unrealized losses included in net income related to assets still held	-0.8	-0.3
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	0	21.6
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	0	21.6
Change in unrealized losses included in net income related to assets still held	$0	$0

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, 2015	Dec. 31, 2014
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, long-term	$1,718.40	$1,695.90
Convertible debentures	976.5
Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, long-term	1,718.40	1,695.90
Short-term borrowings	450	400
Commercial paper	638.8
Convertible debentures	976.5	974.4
Notes Payable	13,774.10	13,777.80
Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, long-term	1,718.40	1,695.90
Short-term borrowings	450	400
Commercial paper	638.8
Convertible debentures	3,098.40	2,581.90
Notes Payable	15,018.30	14,794.80
Estimated Fair Value [Member] \| Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, long-term	1,718.40	1,695.90
Short-term borrowings	0	0
Commercial paper	0
Convertible debentures	0	0
Notes Payable	0	0
Estimated Fair Value [Member] \| Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, long-term	0	0
Short-term borrowings	450	400
Commercial paper	638.8
Convertible debentures	3,098.40	2,581.90
Notes Payable	15,018.30	14,794.80
Estimated Fair Value [Member] \| Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets, long-term	0	0
Short-term borrowings	0	0
Commercial paper	0
Convertible debentures	0	0
Notes Payable	$0	$0

Income_Taxes_Narrative_Details

Income Taxes (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Income tax expense	$703.90	$438.70
Effective tax rate	44.90%	38.80%
Health Insurance Provider Fee, nondeductible expense	$113.30	$80.50

Retirement_Benefits_Components

Retirement Benefits (Components Of Net Periodic Benefit (Credit) Cost) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$3.30	$3.30
Interest cost	17	18.5
Expected return on assets	-35.7	-34.4
Recognized actuarial loss	6.4	5.3
Settlement loss	1.3	1.1
Amortization of prior service credit	-0.2	-0.2
Net periodic (credit) benefit cost	-7.9	-6.4
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.5	0.8
Interest cost	5.9	6.6
Expected return on assets	-5.9	-5.8
Recognized actuarial loss	3.8	2.3
Settlement loss	0	0
Amortization of prior service credit	-3.6	-3.6
Net periodic (credit) benefit cost	$0.70	$0.30

Debt_Carrying_Value_Of_Longter

Debt (Carrying Value Of Long-term Debt) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Current portion of long-term debt	($625)	($625)
Long-term debt, less current portion	$14,764.40	$14,127.20

Debt_Narrative_Details

Debt (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Debt Instrument [Line Items]
Senior unsecured notes, carrying value	$13,749.20
Debt instruments, repurchased face amount	13
Senior unsecured notes, repurchase price	16.2
Loss on extinguishment of debt	3.4	3
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	638.8
Federal Home Loan Bank Advances [Member]
Debt Instrument [Line Items]
Federal Home Loan Bank, advances, short-term	$450
Debt instrument interest rate	0.19%

Debt_Convertible_Debenture_Ter

Debt (Convertible Debenture Terms) (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015
Debt Instruments [Abstract]
Outstanding principal amount	$1,500
Unamortized debt discount	523.5
Net debt carrying amount	976.5
Equity component carrying amount	$543.60
Conversion rate (shares of common stock per $1,000 of principal)	13.3953
Effective conversion price (per $1,000 of principal amount) per share	$74.65

Commitments_And_Contingencies_

Commitments And Contingencies (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Commitments And Contingencies [Line Items]
Possible losses, in excess of established reserves, minimum	$0
Possible losses, in excess of established reserves, maximum	250
International Business Machines Corporation [Member]
Commitments And Contingencies [Line Items]
Long-term purchase commitment, amount	452.7
Affiliated Computer Services, Inc. [Member]
Commitments And Contingencies [Line Items]
Long-term purchase commitment, amount	$62.90
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, 2015	Mar. 31, 2014
Capital [Abstract]
Declaration date	27-Jan-15	28-Jan-14
Record date	10-Mar-15	10-Mar-14
Payment date	25-Mar-15	25-Mar-14
Cash dividends per share	$0.63	$0.44
Total payment	$166.60	$123.40

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, 2015	Mar. 31, 2014	Apr. 14, 2015
Equity, Class of Treasury Stock [Line Items]
Shares repurchased	5.7	14.3
Average price per share	$136.88	$88.14
Aggregate cost	$774.10	$1,262.80
Authorization remaining at the end of each period	4,917.60	2,428.20
Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased			0.5
Average price per share			$154.99
Aggregate cost			79.9
Authorization remaining at the end of each period			$4,837.70

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, 2015
Number of Shares [Roll Forward]
Outstanding at beginning of period, Number of Shares	7.3
Granted, Number of Shares	1.2
Exercised, Number of Shares	-1.5
Forfeited or expired, Number of Shares	-0.1
Outstanding at end of period, Number of Shares	6.9
Exercisable at end of period, Number of Shares	4
Weighted-Average Option Price Per Share [Roll Forward]
Outstanding at beginning of period, Weighted-Average Option Price per Share	$70.30
Granted, Weighted-Average Option Price per Share	$146.93
Exercised, Weighted-Average Option Price per Share	$67.75
Forfeited or expired, Weighted-Average Option Price per Share	$77.92
Outstanding at end of period, Weighted-Average Option Price per Share	$84.31
Exercisable at end of period, Weighted-Average Option Price per Share	$66.61
Outstanding at end of period, Weighted-Average Remaining Contractual Life	4 years 9 months 18 days
Exercisable at end of period, Weighted-Average Remaining Contractual Life	2 years 11 months 1 day
Outstanding at end of period, Aggregate Intrinsic Value	$487
Exercisable at end of period, Aggregate Intrinsic Value	$352.10

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, 2015	Mar. 31, 2014
Restricted Stock Shares and Units [Roll Forward]
Nonvested at Beginning Balance, Restricted Stock Shares and Units	3.6
Granted, Restricted Stock Shares and Units	0.9	1.3
Vested, Restricted Stock Shares And Units	-1.5
Forfeited, Restricted Stock Shares And Units	0
Nonvested at Ending Balance, Restricted Stock Shares and Units	3
Weighted-Average Grant Date Fair Value Per Share [Roll Forward]
Nonvested at Beginning Balance, Weighted-Average Grant Date Fair Value per Share	$75.63
Granted, Weighted-Average Grant Date Fair Value per Share	$146.85	$89.43
Vested, Weighted-Average Grant Date Fair Value per Share	$72.13
Forfeited, Weighted-Average Grant Date Fair Value per Share	$0
Nonvested at Ending Balance, Weighted-Average Grant Date Fair Value per Share	$98.64

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, 2015	Mar. 31, 2014
Capital [Abstract]
Risk-free interest rate	1.96%	2.16%
Volatility factor	31.00%	35.00%
Quarterly dividend yield	0.43%	0.50%
Weighted-average expected life (years)	4 years 0 months	3 years 9 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, 2015	Mar. 31, 2014
Capital [Abstract]
Options granted during the period	$33.95	$22.20
Restricted stock and stock awards granted during the period	$146.85	$89.43

Capital_Stock_Narrative_Detail

Capital Stock (Narrative) (Details) (USD $)	3 Months Ended		0 Months Ended	1 Months Ended	0 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Apr. 14, 2015	Apr. 29, 2015	Feb. 04, 2014	Oct. 02, 2014
Option Indexed to Issuer's Equity [Line Items]
Repurchase and retirement of common stock, shares	5.7	14.3
Increase in stock repurchase program authorization						$5,000
Call Option [Member]
Option Indexed to Issuer's Equity [Line Items]
Repurchase and retirement of common stock, shares	1.8
Average strike price	132.13
Put Option [Member]
Option Indexed to Issuer's Equity [Line Items]
Options indexed to issuer's equity, shares	4.2
Options expired unexercised	2.4
Remaining unexpired options	1.8
Shares subject to mandatory repurchase upon exipriation of the option contract if the market price of our common stock is less than the option strike price	1.8
Subsequent Event [Member]
Option Indexed to Issuer's Equity [Line Items]
Repurchase and retirement of common stock, shares			0.5
Subsequent Event [Member] \| Call Option [Member]
Option Indexed to Issuer's Equity [Line Items]
Average strike price				$144.06
Options indexed to issuer's equity, shares				0.4
Subsequent Event [Member] \| Put Option [Member]
Option Indexed to Issuer's Equity [Line Items]
Options indexed to issuer's equity, shares				1
Shares subject to mandatory repurchase upon exipriation of the option contract if the market price of our common stock is less than the option strike price				1
Accelerated Share Repurchase Agreement [Member]
Option Indexed to Issuer's Equity [Line Items]
Repurchase and retirement of common stock, shares		6.6
Accelerated share repurchase agreement, amount					$600

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income (Reconciliation Of The Components Of Accumulated Other Comprehensive Income) (Details) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Investments, gross unrealized gains	$1,198.80	$1,156.50	$1,154.90
Investments, gross unrealized losses	-135.5	-161.8
Investments, net pretax unrealized gains	1,063.30	994.7
Deferred tax liability	-375.3	-345.4
Net unrealized gains on investments	688	649.3
Non-credit component of other than temporary impairments on investments, unrealized losses	-1.4	0
Non-credit component of other than temporary impairments on investments, deferred tax asset	0.5	0
Net unrealized non-credit component of other than temporary impairments on investments	-0.9	0
Cash flow hedges, gross unrealized losses	-53.8	-48.6
Cash flow hedges, deferred tax asset	18.8	17
Net unrealized losses on cash flow hedges	-35	-31.6
Defined benefit pension plans, deferred net actuarial loss	-556.1	-426.4
Defined benefit pension plans, deferred prior service credits	2.1	8.4
Defined benefit pension plans, deferred tax asset	220.3	167.5
Net unrecognized periodic benefit costs for defined benefit pension plans	-333.7	-250.5
Postretirement benefit plans, deferred net actuarial loss	-194.8	-154.7
Postretirement benefit plans, deferred prior service credits	71.8	86.2
Defined benefit pension plans, deferred tax asset	48.8	27.4
Net unrecognized periodic benefit costs for postretirement benefit plans	-74.2	-41.1
Foreign currency translation adjustments, gross unrealized (losses) gains	-9.7	2
Foreign currency translation adjustments, deferred tax asset (liability)	3.4	-0.7
Net unrealized (losses) gains on foreign currency translation adjustments	-6.3	1.3
Accumulated other comprehensive income	$237.90	$327.40	$171.90

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income (Other Comprehensive Income (Loss) Reclassification Adjustments) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net holding gain on investment securities arising during the period, net of tax	$39.30	$120.20
Reclassification adjustment for net realized gain on investment securities, net of tax	21.1	20.1
Total reclassification adjustment on investments	60.4	140.3
Non-credit component of other-than-temporary impairments on investments, net of tax	3.5	0.5
Cash flow hedges, holding gain, net of tax	0.9	0.7
Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, net of tax	4.7	2.9
Foreign currency translation adjustment, net of tax	-3.5	-0.2
Net gain recognized in other comprehensive income (loss), net of tax	$66	$144.20

Accumulated_Other_Comprehensiv4

Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income Reclassification Adjustments (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) Reclassification Adjustments (Parantheticals) [Abstract]
Net holding gain (loss) on investment securities arising during the period, tax expense (benefit)	$33.40	$67.50
Reclassification adjustment for net realized gain (loss) on investment securities, tax expense (benefit)	11.4	10.8
Non-credit component of other than temporary impairments on investments, tax expense (benefit)	1.9	0.3
Cash flow hedges, holding gain (loss), tax expense (benefit)	0.5	0.4
Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, tax expense	3	1.9
Foreign currency translation adjustment, tax expense (benefit)	-1.9	0
Net gain recognized in other comprehensive income (loss), tax expense (benefit)	$48.30	$80.90

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, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Denominator for basic earnings per share - weighted-average shares	266.6	284.9
Effect of dilutive securities â€“ employee stock options, non-vested restricted stock awards and convertible debentures	13.8	7.7
Denominator for diluted earnings per share	280.4	292.6

Earnings_Per_Share_Narrative_D

Earnings Per Share (Narrative) (Details)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Weighted average shares excluded from denominator for diluted earnings per share because the stock options were anti-dilutive	0.4	0.6
Restricted stock units issued under stock incentive plan	0.9	1.3
Restricted stock units excluded from the denominator for diluted earnings per share	0.5	0.7

Segment_Information_Financial_

Segment Information (Financial Data By Reportable Segment) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Operating revenue	$18,851.40	$17,644.80
Operating gain (loss)	1,579.30	1,118.70
Commercial and Specialty Business [Member]
Segment Reporting Information [Line Items]
Operating revenue	9,366.90	9,697.50
Operating gain (loss)	1,267	886.1
Government Business [Member]
Segment Reporting Information [Line Items]
Operating revenue	9,480.10	7,941.30
Operating gain (loss)	324.4	239.6
Other [Member]
Segment Reporting Information [Line Items]
Operating revenue	4.4	6
Operating gain (loss)	($12.10)	($7)

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, 2015	Mar. 31, 2014
Segment Reporting [Abstract]
Reportable segments operating revenues	$18,851.40	$17,644.80
Net investment income	167.6	183.7
Net realized gains on investments	46.5	41.7
Other-than-temporary impairment losses recognized in income	-14	-10.8
Total revenues	$19,051.50	$17,859.40

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, 2015	Mar. 31, 2014
Segment Reporting [Abstract]
Reportable segments operating gain	$1,579.30	$1,118.70
Net investment income	167.6	183.7
Net realized gains on investments	46.5	41.7
Other-than-temporary impairment losses recognized in income	-14	-10.8
Interest expense	-154.4	-146.2
Amortization of other intangible assets	-52.5	-54
Loss on extinguishment of debt	-3.4	-3
Income from continuing operations before income tax expense	$1,569.10	$1,130.10