Aetna 10-Q 24 Apr 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information Document	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014
Entity Information [Line Items]	'
Entity Registrant Name	'AETNA INC /PA/
Entity Central Index Key	'0001122304
Current Fiscal Year End Date	'--12-31
Entity Filer Category	'Large Accelerated Filer
Document Type	'10-Q
Document Period End Date	31-Mar-14
Document Fiscal Year Focus	'2014
Document Fiscal Period Focus	'Q1
Amendment Flag	'false
Entity Common Stock, Shares Outstanding	357.4

Consolidated_Statements_of_Inc

Consolidated Statements of Income (Unaudited) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Revenue:	'		'
Health care premiums	$11,911.70		$7,785.80
Other premiums	561.6		521.3
Fees and other revenue	1,248.80	[1]	966.4	[1]
Net investment income	244.2		235.1
Net realized capital gains	28.5		30.3
Total revenue	13,994.80		9,538.90
Benefits and expenses:	'		'
Health care costs	9,576.30	[2]	6,379.50	[2]
Current and future benefits	578.7		559.3
Operating expenses:	'		'
Selling expenses	402.8		297.2
General and administrative expenses	2,047.60		1,442
Total operating expenses	2,450.40		1,739.20
Interest expense	85.6		77.8
Amortization of other acquired intangible assets	62.2		32.4
Loss on early extinguishment of long-term debt	91.9		0
Total benefits and expenses	12,845.10		8,788.20
Income before income taxes	1,149.70		750.7
Income taxes:	'		'
Current	418.5		266.8
Deferred	61.8		-7
Total income taxes	480.3		259.8
Net Income including non-controlling interests	669.4		490.9
Less: Net income attributable to non-controlling interests	3.9		0.8
Net income attributable to Aetna	665.5		490.1
Earnings per common share:	'		'
Basic	$1.84		$1.50
Diluted	$1.82		$1.48
Administrative Services Contract Member Co Payments And Plan Sponsor Reimbursements	21.8		22.3
Pharmaceutical And Processing Costs	275.4		268.9
Insured Member Co Payments	$30.60		$31
[1]	Fees and other revenue include administrative services contract member co-payments and plan sponsor reimbursements related to our mail order and specialty pharmacy operations of $21.8 million and $22.3 million (net of pharmaceutical and processing costs of $275.4 million and $268.9 million) for the three months ended March 31, 2014 and 2013, respectively.
[2]	Health care costs have been reduced by Insured member co-payments related to our mail order and specialty pharmacy operations of $30.6 million and $31.0 million for the three months ended March 31, 2014 and 2013, respectively.

Consolidated_Statement_of_Comp

Consolidated Statement of Comprehensive Income (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Net Income including non-controlling interests	$669.40		$490.90
Other comprehensive (loss) income	125.7		-80.5
Comprehensive Income including non-controlling interests	795.1		410.4
Comprehensive income attributable to non-controlling interests	3.9		0.8
Comprehensive Income attributable to Aetna	791.2		409.6
Net Unrealized Gains (Losses) Previously Impaired Securities [Member]	'		'
Net unrealized gains (losses)	1.1	[1]	-9.4	[1]
Less: Net unrealized gains (losses) on securities, reclassification of gains to earnings	0.4	[1]	-3.7	[1]
Other comprehensive (loss) income	0.7	[1]	-5.7	[1]
Other Securities [Member]	'		'
Net unrealized gains (losses)	137.2		-78.5
Less: Net unrealized gains (losses) on securities, reclassification of gains to earnings	-3.3		15.8
Other comprehensive (loss) income	140.5		-94.3
Foreign Currency and Derivative Gain (Loss) [Member]	'		'
Net unrealized gains (losses)	-12.5		6.7
Less: Foreign currency and derivatives reclassification of losses to earnings	10.1		-0.8
Other comprehensive (loss) income	-22.6		7.5
Pension and OPEB Plan [Member]	'		'
Amortization of net actuarial losses	7.7		12.6
Amortization of prior service cost	-0.6		-0.6
Other comprehensive (loss) income	$7.10		$12
[1]	Represents unrealized gains on the non-credit related component of impaired debt securities that we do not intend to sell and subsequent changes in the fair value of any previously impaired security.

Consolidated_Statement_of_Comp1

Consolidated Statement of Comprehensive Income (Paranthetical) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Net Unrealized Gains (Losses) Previously Impaired Securities [Member]	'		'
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax	$1.70	[1]	($14.50)	[1]
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, before Tax	0.6	[1]	-5.7	[1]
Other Securities [Member]	'		'
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax	211		-120.7
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, before Tax	-5		25.1
Foreign Currency and Derivative Gain (Loss) [Member]	'		'
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax	-19.2		10.3
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment Realized upon Sale or Liquidation, before Tax	15.6		-1.3
Pension and OPEB Plan [Member]	'		'
Amortization of net actuarial loss, before tax	-11.9		-19.4
Amortization of prior service cost, before tax	$1		$1
[1]	Represents unrealized (losses) gains on the non-credit related component of impaired debt securities that we do not intend to sell and subsequent changes in the fair value of any previously impaired security.

Consolidated_Balance_Sheets_Un

Consolidated Balance Sheets (Unaudited) (USD $)	Mar. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Current assets:	'		'
Cash and cash equivalents	$2,074.10		$1,412.30
Investments	2,209.80		2,063.80
Premiums receivable, net	1,700.20		1,331.20
Other receivables, net	1,809		1,780.80
Accrued investment income	212.6		211.1
Collateral received under securities loan agreements	720.7		792.6
Income taxes receivable	0		69.2
Deferred income taxes	449.8		521.5
Other current assets	2,238.60		1,536.40
Total current assets	11,414.80		9,718.90
Long-term investments	21,290.40		20,935
Reinsurance recoverables	776.5		782.7
Goodwill	10,227.50		10,227.50
Other acquired intangible assets, net	2,031.90		2,094.10
Property and equipment, net	704.1		721.9
Other long-term assets	1,494.10		1,419.20
Separate Account Assets	4,179.70		3,972.50
Total assets	52,119		49,871.80
Current liabilities:	'		'
Health care costs payable	5,007.20		4,547.40
Future policy benefits	729.4		734.4
Unpaid claims	726.1		705.4
Unearned premiums	573.3		458.7
Policyholders' funds	1,925.70		1,727.30
Collateral payable under securities loan and repurchase agreements	877		792.6
Current portion of long-term debt	620.2	[1]	387.3	[1]
Income taxes payable	286.6		0
Accrued expenses and other current liabilities	3,835.70		3,226.90
Total current liabilities	14,581.20		12,580
Future policy benefits	6,609		6,656.80
Unpaid claims	1,630.30		1,619.30
Policyholders' funds	1,184.10		1,188
Long-term debt, less current portion	7,618.40		7,865.30
Deferred income taxes	940.9		864.2
Other long-term liabilities	1,014.40		1,047.50
Separate Accounts liabilities	4,179.70		3,972.50
Total liabilities	37,758		35,793.60
Commitments and contingencies (Note 13)	'		'
Shareholders' equity:	'		'
Common stock ($.01 par value; 2.6 billion shares authorized and 357.4 million shares issued and outstanding in 2014; 2.6 billion shares authorized and 362.2 million shares issued and outstanding in 2013) and additional paid-in capital	4,414.50		4,382.20
Retained earnings	10,675.50		10,555.40
Accumulated other comprehensive loss	-786.4		-912.1
Total Aetna shareholders' equity	14,303.60		14,025.50
Non-controlling Interests	57.4		52.7
Total equity	14,361		14,078.20
Total liabilities and equity	$52,119		$49,871.80
[1]	At March 31, 2014, our 6.125% senior notes due January 2015 and 6.3% senior notes due August 2014 are classified as current in the accompanying consolidated balance sheet.

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Paranthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Common Stock, Par or Stated Value Per Share	$0.01	$0.01
Common Stock, Shares Authorized	2,600,000,000	2,600,000,000
Common Stock, Shares, Issued	357,400,000	362,200,000
Common Stock, Shares, Outstanding	357,400,000	362,200,000

Consolidated_Statements_of_Sha

Consolidated Statements of Shareholders' Equity (Unaudited) (USD $)	Total	Common Stock [Member]	Common Stock Including Additional Paid in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Parent [Member]	Noncontrolling Interest [Member]
In Millions, except Share data, unless otherwise specified
Balance at beginning of period at Dec. 31, 2012	'	'	$1,095.30	$10,343.90	($1,033.40)	$10,405.80	'
Total equity at beginning of period at Dec. 31, 2012	10,429.20	'	'	'	'	'	'
Stockholders' Equity Attributable to Noncontrolling Interest at beginning of period at Dec. 31, 2012	'	'	'	'	'	'	23.4
Balance at beginning of period (in shares) at Dec. 31, 2012	'	327,600,000	'	'	'	'	'
Comprehensive income:	'	'	'	'	'	'	'
Net income	490.1	0	0	490.1	0	490.1	'
Net Income Attributable to Non-controlling Interest	0.8	'	'	'	'	'	0.8
Net Income including non-controlling interests	490.9	'	'	'	'	'	'
Other increases (decreases) in noncontrolling interests	21.7	0	0	0	0	0	21.7
Other comprehensive (loss) income	-80.5	0	0	0	-80.5	-80.5	0
Common shares issued for benefit plans, including tax benefits	114.8	'	114.8	0	0	114.8	0
Common shares issued for benefit plans, including tax benefits (in shares)	'	2,000,000	'	'	'	'	'
Repurchases of common shares	-184.1	'	0	-184.1	0	-184.1	0
Repurchases of common shares (in shares)	'	-3,700,000	'	'	'	'	'
Dividends declared	-65.2	0	0	-65.2	0	-65.2	0
Total equity at end of period at Mar. 31, 2013	10,726.80	'	'	'	'	'	'
Stockholders' Equity Attributable to Noncontrolling Interest at end of period at Mar. 31, 2013	'	'	'	'	'	'	45.9
Balance at end of period at Mar. 31, 2013	'	'	1,210.10	10,584.70	-1,113.90	10,680.90	'
Balance at end of period (in shares) at Mar. 31, 2013	'	325,900,000	'	'	'	'	'
Balance at beginning of period at Dec. 31, 2013	14,025.50	'	4,382.20	10,555.40	-912.1	14,025.50	'
Total equity at beginning of period at Dec. 31, 2013	14,078.20	'	'	'	'	'	'
Stockholders' Equity Attributable to Noncontrolling Interest at beginning of period at Dec. 31, 2013	52.7	'	'	'	'	'	52.7
Balance at beginning of period (in shares) at Dec. 31, 2013	362,200,000	362,200,000	'	'	'	'	'
Comprehensive income:	'	'	'	'	'	'	'
Net income	665.5	0	0	665.5	0	665.5	'
Net Income Attributable to Non-controlling Interest	3.9	'	'	'	'	'	3.9
Net Income including non-controlling interests	669.4	'	'	'	'	'	'
Other increases (decreases) in noncontrolling interests	0.8	0	0	0	0	0	0.8
Other comprehensive (loss) income	125.7	0	0	0	125.7	125.7	0
Common shares issued for benefit plans, including tax benefits	32.4	'	32.4	0	0	32.4	0
Common shares issued for benefit plans, including tax benefits (in shares)	'	-1,700,000	'	'	'	'	'
Repurchases of common shares	-465	'	-0.1	-464.9	0	-465	0
Repurchases of common shares (in shares)	-7,000,000	-6,500,000	'	'	'	'	'
Dividends declared	-80.5	0	0	-80.5	0	-80.5	0
Total equity at end of period at Mar. 31, 2014	14,361	'	'	'	'	'	'
Stockholders' Equity Attributable to Noncontrolling Interest at end of period at Mar. 31, 2014	57.4	'	'	'	'	'	57.4
Balance at end of period at Mar. 31, 2014	$14,303.60	'	$4,414.50	$10,675.50	($786.40)	$14,303.60	'
Balance at end of period (in shares) at Mar. 31, 2014	357,400,000	357,400,000	'	'	'	'	'

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (Unaudited) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:	'	'
Net Income including non-controlling interests	$669.40	$490.90
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Net realized capital gains	-28.5	-30.3
Depreciation and amortization	154.7	108.6
Amortization of debt fair value adjustment	-15.1	0
Equity in earnings of affiliates, net	-20.6	-18.3
Stock-based compensation expense	38.8	24.5
Amortization of net investment premium	18.3	9.5
Loss on early extinguishment of long-term debt	91.9	0
Changes in assets and liabilities:	'	'
Accrued investment income	-1.5	2.9
Premiums due and other receivables	-337	-413.5
Income taxes	420.3	189.9
Other assets and other liabilities	-70.6	-103.5
Health care and insurance liabilities	501.4	280.2
Other, net	0.7	2.9
Net cash provided by operating activities	1,422.20	543.8
Cash flows from investing activities:	'	'
Proceeds from sales and maturities of investments	2,219.60	2,711
Cost of investments	-2,379.60	-2,493.60
Additions to property, equipment and software	-93.8	-86.1
Other, net	0	2.5
Net cash used for investing activities	-253.8	133.8
Cash flows from financing activities:	'	'
Repayment of long-term debt	-839.7	0
Issuance of long-term debt	741.9	0
Net issuance of short-term debt	0	99.9
Deposits and interest credited for investment contracts	1.1	1.2
Withdrawals of investment contracts	-1	-4.1
Common Shares Issued Under Benefit Plans	-17	37.8
Stock-based compensation tax benefits	13.9	55
Proceeds from repurchase agreements	156.2	0
Common shares repurchased	-465	-184.1
Dividends paid to shareholders	-81.6	-65.5
Collateral on interest rate swaps	-16.7	9.2
Contributions (distributions) from noncontrolling interests	1.3	21.7
Net cash used for financing activities	-506.6	-28.9
Net increase in cash and cash equivalents	661.8	648.7
Cash and cash equivalents, beginning of period	1,412.30	2,579.20
Cash and cash equivalents, end of period	2,074.10	3,227.90
Supplemental cash flow information:	'	'
Interest paid	72.9	32.4
Income taxes paid	$46.20	$13.40

Organization

Organization	3 Months Ended
	Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Organization	'
	1	Organization
	We conduct our operations in three business segments:
	•	Health Care consists of medical, pharmacy benefit management services, dental, behavioral health and vision plans offered on both an Insured basis (where we assume all or a majority of the risk for medical and dental care costs) and an employer-funded basis (where the plan sponsor under an administrative services contract (“ASC”) assumes all or a majority of this risk) and emerging businesses products and services, such as Accountable Care Solutions (“ACS”), that complement and enhance our medical products. Medical products include point-of-service (“POS”), preferred provider organization (“PPO”), health maintenance organization (“HMO”) and indemnity benefit plans. Medical products also include health savings accounts (“HSAs”) and Aetna HealthFund®, consumer-directed health plans that combine traditional POS or PPO and/or dental coverage, subject to a deductible, with an accumulating benefit account (which may be funded by the plan sponsor and/or the member in the case of HSAs). We also offer Medicare and Medicaid products and services and other medical products, such as medical management and data analytics services, medical stop loss insurance, workers' compensation administrative services and products that provide access to our provider network in select geographies.
	•	Group Insurance primarily includes group life insurance and group disability products. Group life insurance products are offered on an Insured basis, and include basic and supplemental group term life, group universal life, supplemental or voluntary programs and accidental death and dismemberment coverage. Group disability products consist primarily of short-term and long-term disability products (and products which combine both), which are offered to employers on both an Insured and an ASC basis, and absence management services offered to employers, which include short-term and long-term disability administration and leave management. Group Insurance also includes long-term care products that were offered primarily on an Insured basis, which provide benefits covering the cost of care in private home settings, adult day care, assisted living or nursing facilities. We no longer solicit or accept new long-term care customers.
	•	Large Case Pensions manages a variety of retirement products (including pension and annuity products) primarily for tax-qualified pension plans. These products provide a variety of funding and benefit payment distribution options and other services. Large Case Pensions also includes certain discontinued products (refer to Note 16 beginning on page 32 for additional information).
	On May 7, 2013 (the “Effective Date”), we completed the acquisition of Coventry Health Care, Inc. (“Coventry”) in a transaction valued at approximately $8.7 billion, including the fair value of Coventry's outstanding debt. Refer to Note 3 beginning on page 8 for additional information.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	2	Summary of Significant Accounting Policies
	Interim Financial Statements
	These interim financial statements necessarily rely on estimates, including assumptions as to annualized tax rates.  In the opinion of management, all adjustments necessary for a fair statement of results for the interim periods have been made.  All such adjustments are of a normal, recurring nature.  The accompanying unaudited consolidated financial statements and related notes should be read in conjunction with the consolidated financial statements and related notes presented in our 2013 Annual Report on Form 10-K (our “2013 Annual Report”).  Certain financial information that is normally included in annual financial statements prepared in accordance with U.S. generally accepted accounting principles (“GAAP”), but that is not required for interim reporting purposes, has been condensed or omitted.  We have omitted certain footnote disclosures that would substantially duplicate the disclosures in our 2013 Annual Report, unless the information contained in those disclosures materially changed and is required by GAAP.  We evaluated subsequent events that occurred after March 31, 2014 through the date the financial statements were issued and determined there were no other items to disclose other than those disclosed in Notes 3 and 10 beginning on pages 8 and 25, respectively.
	Reclassifications
	Certain reclassifications were made to 2013 financial information to conform with the 2014 presentation.
	Principles of Consolidation
	The accompanying unaudited consolidated financial statements have been prepared in accordance with GAAP and include the accounts of Aetna and the subsidiaries we control.  All significant intercompany balances have been eliminated in consolidation.
	Accounting for certain provisions of the Patient Protection and Affordable Care Act and the Health Care and Education Reconciliation Act of 2010 (collectively, “Health Care Reform” or “ACA”)
	We are participating in certain public health insurance exchanges established pursuant Health Care Reform. Under regulations established by the U.S. Department of Health and Human Services (“HHS”), HHS pays us a portion of the premium (“Premium Subsidy”) and/or a portion of the health care costs (“Cost Sharing Subsidy”) for low-income individual members. In addition, HHS administers certain risk management programs as described below.
	We recognize monthly premiums received from members and the Premium Subsidy as premium revenue ratably over the contract period. The Cost Sharing Subsidy offsets health care costs when incurred. We record a liability if the Cost Sharing Subsidy is paid in advance or a receivable if incurred health care costs exceed the Cost Sharing Subsidy received to date.
	Accounting for Health Care Reform's Reinsurance, Risk Adjustment and Risk Corridor (the “3Rs”)
	Reinsurance
	Health Care Reform established a temporary three-year reinsurance program, whereby all issuers of major medical commercial insurance products and self-insured plan sponsors are required to contribute funding in amounts set by HHS. Funds collected will be utilized to reimburse issuers' high claims costs incurred for qualified individual members. The expense related to this required funding is reflected in general and administrative expenses for all of our insurance products with the exception of products associated with qualified individual members; this expense for qualified individual members is reflected as a reduction of premium revenue. When annual claim costs incurred by our qualified individual members exceed a specified attachment point, we are entitled to certain reimbursements from this program. We record a receivable and offset health care costs to reflect our estimate of these recoveries.
	Risk Adjustment
	Health Care Reform established a permanent risk adjustment program to transfer funds from qualified individual and small group insurance plans with below average risk scores to those respective plans with above average risk scores. Based on the risk of our qualified plan members compared to the risk of members of other qualified plans in comparable markets, we estimate our ultimate 2014 risk adjustment receivable or payable and reflect the pro-rata year-to-date impact as an adjustment to our premium revenue.
	Risk Corridor
	Health Care Reform established a temporary three-year risk sharing program. Under this program we make (or receive) a payment to (or from) HHS based on the ratio of allowable costs to target costs (as defined by Health Care Reform). Risk corridor payments from HHS will be limited to the extent of the risk corridor collections received by HHS over the duration of the program. We record a risk corridor receivable or payable as an adjustment to premium revenue on a pro-rata year-to-date basis based on our estimate of the ultimate 2014 risk sharing amount.
	We will perform a final reconciliation and settlement with HHS of the 2014 Cost Sharing Subsidy and 3Rs in 2015.
	New Accounting Standards
	Fees Paid to the Federal Government by Health Insurers
	Effective January 1, 2014, we adopted new accounting guidance relating to the recognition and income statement reporting of the mandated fee to be paid to the federal government by health insurers. This guidance applies to the new health insurer fee (“HIF”) included in Health Care Reform. This new accounting guidance resulted in the establishment on January 1, 2014, of a liability for our portion of the entire estimated 2014 annual HIF. This amount is reflected in accrued expenses and other liabilities with a corresponding amount reflected in other current assets.  The pro-rata year-to-date portion of the annual HIF is reflected on a straight-line basis in general and administrative expenses with a corresponding reduction in other current assets.  The HIF for 2014 is expected to be paid no later than September 30, 2014 and is not tax deductible.
	Amendments to the Scope, Measurement and Disclosure Requirements of Investment Companies
	Effective January 1, 2014, we adopted new accounting guidance relating to the approach for determining whether an entity is considered an investment company for accounting purposes. This guidance clarified the characteristics and set measurement and disclosure requirements for an investment company for accounting purposes. The adoption of this new guidance did not have an impact on our financial position or operating results.
	Future Application of Accounting Standards
	Accounting for Investments in Qualified Affordable Housing Projects
	Effective January 1, 2015, we will be permitted to make an accounting policy election to adopt new accounting guidance relating to the recognition of amortization of investments in qualified affordable housing projects. The guidance sets forth a new method of measurement, referred to as the proportional amortization method, under which income and expense items related to qualified affordable housing projects would be allocated to the income taxes line item. If we elect to adopt this new guidance, such adoption is not expected to have a material impact on our financial position or operating results.
	Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity
	Effective January 1, 2015, we will adopt amended accounting guidance related to when an entity reports a discontinued operation in its financial position and operating results.  The guidance clarifies that a discontinued operation is required to be reported if the disposal represents a significant shift that has (or will have) a major effect on an entity’s major operations and financial results when a component of an entity or a group of components of an entity are either classified as held for sale or are disposed of by sale.  The amendments also require additional disclosures about discontinued operations. If we have a discontinued operation after the effective date, these changes could result in increased reporting and disclosure requirements in our financial statements.

Acquisitions_Completed_Disposi

Acquisitions, Completed Disposition	3 Months Ended
	Mar. 31, 2014
Business Combinations [Abstract]	'
Completed Acquisition	'
	3	Acquisitions; Completed Disposition
	Acquisition of the InterGlobal Group
	In April 2014, we acquired the InterGlobal group, a company that specializes in international private medical insurance for groups and individuals in the Middle East, Asia, Africa and Europe. The goodwill related to this acquisition will be assigned to our Health Care segment. The purchase price was not material. The transaction closed after March 31, 2014, and therefore has not been reflected in these financial statements.
	Acquisition of Coventry
	On August 19, 2012, we entered into a definitive agreement (as amended, the “Merger Agreement”) to acquire Coventry. On the Effective Date, we acquired Coventry in a transaction valued at approximately $8.7 billion, including the $1.8 billion fair value of Coventry's outstanding long-term debt.
	Pursuant to the terms of the Merger Agreement, an Aetna subsidiary merged with and into Coventry (the “Merger”), with Coventry continuing as the surviving corporation and a wholly-owned subsidiary of Aetna. Under the terms of the Merger Agreement, Coventry stockholders received $27.30 in cash and 0.3885 of an Aetna common share for each share of Coventry common stock (including restricted shares but excluding shares held by Coventry as treasury stock) outstanding at the effective time of the Merger. As a result, on the Effective Date, we issued approximately 52.2 million Aetna common shares, with a fair value of approximately $3.1 billion and paid approximately $3.8 billion in cash in exchange for all of the outstanding shares of Coventry common stock and outstanding awards. Substantially all of Coventry's outstanding equity awards vested and were paid out in cash and canceled in connection with the Merger. An insignificant amount of outstanding Coventry equity awards that pursuant to their terms did not vest at the effective time of the Merger were converted into cash-settled Aetna restricted stock units in connection with the Merger. We funded the cash portion of the purchase price with a combination of proceeds from the issuance of long-term debt, commercial paper and available cash on hand.
	The transaction has been accounted for using the acquisition method of accounting which requires, among other things, the assets acquired and liabilities assumed to be recognized at their fair values at the Effective Date.
	The amounts recognized for certain assets acquired and liabilities assumed are preliminary until the initial accounting for the acquisition is complete. The following items, among others, are considered preliminary until we gather sufficient information for the initial accounting to be complete:
	•	the nature and amounts recognized for current and deferred income tax assets and liabilities;
	•	the nature, amounts recognized and measurement basis of certain liabilities, including liabilities arising from contingencies recognized at acquisition; and
	•	quantitative information related to goodwill recorded at acquisition.
	Pro Forma Impact of Acquisition
	The following table presents supplemental pro forma information for the three months ended March 31, 2013, as if the Merger had occurred on January 1, 2012. The unaudited pro forma consolidated results are not necessarily indicative of what our consolidated results would have been had the Merger been completed on January 1, 2012. In addition, the unaudited pro forma consolidated results do not purport to project the future results of the combined company nor do they reflect the expected realization of any cost savings associated with the Merger.
		Three Months Ended
	(Millions, except per common share data)	31-Mar-13
	Total revenue	$	12,939.40
	Net income attributable to Aetna	638.6
	Earnings per share:
	Basic	$	1.69
	Diluted	1.67
	The unaudited pro forma consolidated results for the three months ended March 31, 2013 reflect the following pro forma adjustments:
	•	Elimination of intercompany transactions between Aetna and Coventry, primarily related to network rental fees.
	•	Foregone interest income associated with cash and cash equivalents and investments assumed to have been used to partially fund the Merger.
	•	Foregone interest income associated with adjusting the amortized cost of Coventry's investment portfolio to fair value as of the completion of the Merger.
	•	Elimination of historical Coventry intangible asset amortization expense and capitalized internal-use software amortization expense and addition of intangible asset amortization expense relating to intangibles valued as part of the acquisition.
	•	Interest expense was reduced for the amortization of the fair value adjustment to long-term debt.
	•	Elimination of transaction-related costs incurred by Aetna and Coventry during 2013.
	•	Adjustment of the above pro forma adjustments for the applicable tax impact.
	•	Conforming adjustments to align Coventry's presentation to Aetna's accounting policies.
	•	Elimination of revenue and directly identifiable costs related to the sale of Aetna's Missouri Medicaid business, Missouri Care, Incorporated (“Missouri Care”), to WellCare Health Plans, Inc. on March 31, 2013.
	Completed Disposition
	In connection with the acquisition of Coventry, on March 31, 2013, we completed the sale of Missouri Care to WellCare Health Plans, Inc. The sale price was not material, and the transaction did not have a material impact on our financial position or operating results.

Earnings_Per_Common_Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Earnings Per Common Share	'
	4	Earnings Per Common Share
	Basic earnings per share (“EPS”) is computed by dividing net income attributable to Aetna by the weighted average number of common shares outstanding during the reporting period.  Diluted EPS is computed in a similar manner, except that the weighted average number of common shares outstanding is adjusted for the dilutive effects of our outstanding stock-based compensation awards, but only if the effect is dilutive.
	The computations of basic and diluted EPS for the three months ended March 31, 2014 and 2013 are as follows:
	(Millions, except per common share data)	2014			2013
	Net income attributable to Aetna	$	665.5		$	490.1
	Weighted average shares used to compute basic EPS	361.6			327.6
	Dilutive effect of outstanding stock-based compensation awards	3.4			3.1
	Weighted average shares used to compute diluted EPS	365			330.7
	Basic EPS	$	1.84		$	1.5
	Diluted EPS	$	1.82		$	1.48
	The stock-based compensation awards excluded from the calculation of diluted EPS for the three months ended March 31, 2014 and 2013 are as follows:
	(Millions)	2014		2013
	Stock appreciation rights ("SARs") (1)	1.3		6.7
	Market stock units ("MSUs") (2)	0.4		0.4
	Performance stock units ("PSUs") (2)	0.7		0.8
	Performance stock appreciation rights ("PSARs") (2)	0.2		—
	(1)	SARs are excluded from the calculation of diluted EPS if the exercise price is greater than the average market price of Aetna common shares during the period (i.e., the awards are anti-dilutive).
	(2)	PSUs, certain MSUs with performance conditions and PSARs are excluded from the calculation of diluted EPS if all necessary performance conditions have not been satisfied at the end of the reporting period.
	All outstanding stock options were included in the calculation of diluted EPS for the three months ended March 31, 2014 and 2013.
	In connection with the May 7, 2013 acquisition of Coventry, we issued approximately 52.2 million Aetna common shares in exchange for all the outstanding shares of Coventry common stock. Those Aetna common shares were outstanding for the entire three months ended March 31, 2014 and weighted accordingly.

Operating_Expenses

Operating Expenses	3 Months Ended
	Mar. 31, 2014
Operating Expenses [Abstract]	'
Operating Expenses	'
	5.     Operating Expenses
	For the three months ended March 31, 2014 and 2013, selling expenses (which include broker commissions, the variable component of our internal sales force compensation and premium taxes) and general and administrative expenses were as follows:
	(Millions)	2014		2013
	Selling expenses	$	402.8	$	297.2
	General and administrative expenses:
	Salaries and related benefits	1,110.70		802.5
	Other general and administrative expenses  (1) (2) (3)	936.9		639.5
	Total general and administrative expenses	2,047.60		1,442.00
	Total operating expenses	$	2,450.40	$	1,739.20
	(1)	The three months ended March 31, 2014 include estimated ACA mandated fees comprised primarily of the HIF and our contribution to the funding of the reinsurance program of $154.8 million and $84.9 million, respectively. Refer to Note 2 beginning on page 6 for additional information on ACA mandated fees.
	(2)	The three months ended March 31, 2014 include $63.7 million of integration-related costs related to the acquisition of Coventry. The three months ended March 31, 2013 include $24.3 million of transaction and integration-related costs related to the acquisition of Coventry, including advisory, legal and other professional services fees and transaction-related payments.
	(3)	In the fourth quarter of 2012, we recorded a charge of $120.0 million pretax related to the settlement of purported class action litigation regarding Aetna's payment practices related to out-of-network health care providers. That charge included the estimated cost of legal fees of plaintiffs' counsel and the costs of administering the settlement. In the first quarter of 2014, we exercised our right to terminate the settlement agreement. As a result, we released the reserve established in connection with the settlement agreement, net of amounts due to the settlement administrator, which reduced first quarter 2014 other general and administrative expenses by $103.0 million pretax. Refer to Note 13 beginning on page 27 for additional information on the termination of the settlement agreement.
	Refer to the reconciliation of operating earnings to net income attributable to Aetna in Note 14 beginning on page 30 for additional information.

Investments

Investments	3 Months Ended
	Mar. 31, 2014
Investments [Abstract]	'
Investments	'
	6.     Investments
	Total investments at March 31, 2014 and December 31, 2013 were as follows:
		March 31, 2014										December 31, 2013
	(Millions)	Current			Long-term			Total				Current			Long-term		Total
	Debt and equity securities available for sale	$	2,121.00		$	18,099.20		$	20,220.20			$	1,977.40		$	17,753.00	$	19,730.40
	Mortgage loans	83.1			1,464.50			1,547.60				84.9			1,464.70		1,549.60
	Other investments	5.7			1,726.70			1,732.40				1.5			1,717.30		1,718.80
	Total investments	$	2,209.80		$	21,290.40		$	23,500.20			$	2,063.80		$	20,935.00	$	22,998.80
	At March 31, 2014, approximately $156 million of investments were pledged as collateral under repurchase agreements. We did not have any repurchase agreements outstanding at December 31, 2013. At March 31, 2014 and December 31, 2013, approximately $696 million and $766 million, respectively, of investments were pledged under securities loan agreements.
	Debt and Equity Securities
	Debt and equity securities available for sale at March 31, 2014 and December 31, 2013 were as follows:
	(Millions)	Amortized			Gross			Gross					Fair
		Cost			Unrealized			Unrealized					Value
					Gains			Losses
	March 31, 2014
	Debt securities:
	U.S. government securities	$	1,325.40		$	77.8		$	(1.1	)			$	1,402.10
	States, municipalities and political subdivisions	4,043.10			182.9			(39.4		)			4,186.60
	U.S. corporate securities	7,725.40			572.3			(55.5		)			8,242.20
	Foreign securities	3,267.00			244.3			(26.1		)			3,485.20
	Residential mortgage-backed securities	960			18			(14.9		)			963.1
	Commercial mortgage-backed securities	1,389.40			84			(3.1		)	(1)		1,470.30
	Other asset-backed securities	336.7			8.2			(1.2		)	(1)		343.7
	Redeemable preferred securities	56.8			9.7			—					66.5
	Total debt securities	19,103.80			1,197.20			(141.3		)			20,159.70
	Equity securities	45.8			19.4			(4.7		)			60.5
	Total debt and equity securities (2)	$	19,149.60		$	1,216.60		$	(146.0	)			$	20,220.20
	December 31, 2013
	Debt securities:
	U.S. government securities	$	1,396.80		$	68.7		$	(3.0	)			$	1,462.50
	States, municipalities and political subdivisions	4,118.50			126.6			(82.8		)			4,162.30
	U.S. corporate securities	7,559.00			493.7			(110.1		)			7,942.60
	Foreign securities	3,209.60			198.9			(53.0		)			3,355.50
	Residential mortgage-backed securities	928.4			16.9			(21.1		)			924.2
	Commercial mortgage-backed securities	1,323.50			88.2			(4.7		)	(1)		1,407.00
	Other asset-backed securities	343.4			8.3			(2.1		)	(1)		349.6
	Redeemable preferred securities	56.8			8.6			—					65.4
	Total debt securities	18,936.00			1,009.90			(276.8		)			19,669.10
	Equity securities	38.5			26.5			(3.7		)			61.3
	Total debt and equity securities (2)	$	18,974.50		$	1,036.40		$	(280.5	)			$	19,730.40
	(1)	At March 31, 2014 and December 31, 2013, we held securities for which we previously recognized $18.6 million and $22.8 million, respectively, of non-credit related impairments in accumulated other comprehensive loss. These securities had a net unrealized capital gain at March 31, 2014 and December 31, 2013 of $5.4 million and $6.6 million, respectively.
	(2)	Investment risks associated with our experience-rated and discontinued products generally do not impact our operating results (refer to Note 16 beginning on page 32 for additional information on our accounting for discontinued products).  At March 31, 2014, debt and equity securities with a fair value of approximately $3.7 billion, gross unrealized capital gains of $348.8 million and gross unrealized capital losses of $28.6 million and, at December 31, 2013, debt and equity securities with a fair value of approximately $3.7 billion, gross unrealized capital gains of $291.3 million and gross unrealized capital losses of $60.3 million were included in total debt and equity securities, but support our experience-rated and discontinued products.  Changes in net unrealized capital gains (losses) on these securities are not reflected in accumulated other comprehensive income.
	The fair value of debt securities at March 31, 2014 is shown below by contractual maturity.  Actual maturities may differ from contractual maturities because securities may be restructured, called or prepaid.
	(Millions)	Fair
		Value
	Due to mature:
	Less than one year	$	949.1
	One year through five years	5,424.20
	After five years through ten years	5,721.00
	Greater than ten years	5,288.30
	Residential mortgage-backed securities	963.1
	Commercial mortgage-backed securities	1,470.30
	Other asset-backed securities	343.7
	Total	$	20,159.70
	Mortgage-Backed and Other Asset-Backed Securities
	All of our residential mortgage-backed securities at March 31, 2014 were issued by the Government National Mortgage Association, the Federal National Mortgage Association or the Federal Home Loan Mortgage Corporation and carry agency guarantees and explicit or implicit guarantees by the U.S. Government.  At March 31, 2014, our residential mortgage-backed securities had an average credit quality rating of AAA and a weighted average duration of 4.9 years.
	Our commercial mortgage-backed securities have underlying loans that are dispersed throughout the United States.  Significant market observable inputs used to value these securities include probability of default and loss severity.  At March 31, 2014, these securities had an average credit quality rating of AA+ and a weighted average duration of 2.5 years.
	Our other asset-backed securities have a variety of underlying collateral (e.g., automobile loans, credit card receivables and home equity loans).  Significant market observable inputs used to value these securities include the unemployment rate, loss severity and probability of default.  At March 31, 2014, these securities had an average credit quality rating of AA+ and a weighted average duration of 2.8 years.
	Unrealized Capital Losses and Net Realized Capital Gains (Losses)
	When a debt or equity security is in an unrealized capital loss position, we monitor the duration and severity of the loss to determine if sufficient market recovery can occur within a reasonable period of time.  We recognize an other-than-temporary impairment (“OTTI”) when we intend to sell a debt security that is in an unrealized capital loss position or if we determine a credit-related loss on a debt or equity security has occurred.
	Summarized below are the debt and equity securities we held at March 31, 2014 and December 31, 2013 that were in an unrealized capital loss position, aggregated by the length of time the investments have been in that position:
		Less than 12 months						Greater than 12 months							Total (1)
	(Millions)	Fair			Unrealized			Fair				Unrealized			Fair		Unrealized
Value		Losses			Value			Losses				Value			Losses
March 31, 2014
Debt securities:
U.S. government securities	$	51.4		$	0.8		$	13.4			$	0.3		$	64.8	$	1.1
States, municipalities and political subdivisions	1,136.10			31.5			155.7				7.9			1,291.80		39.4
U.S. corporate securities	1,558.40			39.3			181.9				16.2			1,740.30		55.5
Foreign securities	569.3			18.9			100.9				7.2			670.2		26.1
Residential mortgage-backed securities	462.5			11.7			35				3.2			497.5		14.9
Commercial mortgage-backed securities	183.2			2.7			24.9				0.4			208.1		3.1
Other asset-backed securities	73.1			1.1			2				0.1			75.1		1.2
Redeemable preferred securities	4.4			—			—				—			4.4		—
Total debt securities	4,038.40			106			513.8				35.3			4,552.20		141.3
Equity securities	—			—			15				4.7			15		4.7
Total debt and equity securities (1)	$	4,038.40		$	106		$	528.8			$	40		$	4,567.20	$	146
December 31, 2013
Debt securities:
U.S. government securities	$	555.9		$	2.7		$	13.4			$	0.3		$	569.3	$	3
States, municipalities and political subdivisions	1,779.90			73.1			132.4				9.7			1,912.30		82.8
U.S. corporate securities	2,196.80			88			170				22.1			2,366.80		110.1
Foreign securities	875.2			43.5			90.9				9.5			966.1		53
Residential mortgage-backed securities	541.1			17.3			35				3.8			576.1		21.1
Commercial mortgage-backed securities	162.4			4.2			25				0.5			187.4		4.7
Other asset-backed securities	87.8			1.9			7.7				0.2			95.5		2.1
Redeemable preferred securities	4.4			—			—				—			4.4		—
Total debt securities	6,203.50			230.7			474.4				46.1			6,677.90		276.8
Equity securities	—			—			16.2				3.7			16.2		3.7
Total debt and equity securities (1)	$	6,203.50		$	230.7		$	490.6			$	49.8		$	6,694.10	$	280.5
(1)	At March 31, 2014 and December 31, 2013, debt and equity securities in an unrealized capital loss position of $28.6 million and $60.3 million, respectively, and with related fair value of $598.0 million and $1.0 billion, respectively, related to experience-rated and discontinued products.
We reviewed the securities in the tables above and concluded that these are performing assets generating investment income to support the needs of our business.  In performing this review, we considered factors such as the quality of the investment security based on research performed by our internal credit analysts and external rating agencies and the prospects of realizing the carrying value of the security based on the investment’s current prospects for recovery.  At March 31, 2014, we did not intend to sell these securities, and we did not believe it was more likely than not that we would be required to sell these securities prior to anticipated recovery of their carrying value.
The maturity dates for debt securities in an unrealized capital loss position at March 31, 2014 were as follows:
	Supporting discontinued and						Supporting remaining							Total
	experience-rated products						products
(Millions)	Fair			Unrealized			Fair				Unrealized			Fair		Unrealized
	Value			Losses			Value				Losses			Value		Losses
Due to mature:
Less than one year	$	—		$	—		$	38.9			$	0.8		$	38.9	$	0.8
One year through five years	25.6			0.3			882.1				8.1			907.7		8.4
After five years through ten years	244.3			7.7			1,457.40				43.3			1,701.70		51
Greater than ten years	285.5			15.3			837.7				46.6			1,123.20		61.9
Residential mortgage-backed securities	10.8			0.2			486.7				14.7			497.5		14.9
Commercial mortgage-backed securities	8.9			0.3			199.2				2.8			208.1		3.1
Other asset-backed securities	7.9			0.1			67.2				1.1			75.1		1.2
Total	$	583		$	23.9		$	3,969.20			$	117.4		$	4,552.20	$	141.3
Net realized capital gains for the three months ended March 31, 2014 and 2013, excluding amounts related to experience-rated contract holders and discontinued products, were as follows:
(Millions)	2014			2013
OTTI losses on debt securities	$	(.2	)	$	(5.8	)
Portion of OTTI losses on debt securities recognized	—			—
in other comprehensive income
Net OTTI losses on debt securities recognized in earnings	(.2		)	(5.8		)
Net realized capital gains, excluding OTTI losses on debt securities	28.7			36.1
Net realized capital gains	$	28.5		$	30.3
The net realized capital gains for the three months ended March 31, 2014 were primarily attributable to the recognition of a gain on the termination of interest rate swaps as well as gains from the sales of debt securities. Refer to Note 10 of Condensed Notes to Consolidated Financial Statements beginning on page 25 for more information on the termination of the outstanding interest rate swaps in the first quarter of 2014. The net realized capital gains for the three months ended March 31, 2013 were primarily attributable to the sale of debt securities.
Excluding amounts related to experience-rated and discontinued products, proceeds from the sale of debt securities and the related gross realized capital gains and losses for the three months ended March 31, 2014 and 2013 were as follows:
(Millions)	2014			2013
Proceeds on sales	$	1,092.80		$	1,375.70
Gross realized capital gains	24.6			37.3
Gross realized capital losses	13			7.4
Mortgage Loans
Our mortgage loans are collateralized by commercial real estate.  During the three months ended March 31, 2014 and 2013 we had the following activity in our mortgage loan portfolio:
(Millions)	2014			2013
New mortgage loans	$	33.9		$	42.5
Mortgage loans fully repaid	19.8			16.9
At March 31, 2014 and December 31, 2013, we had no material problem, restructured or potential problem mortgage loans.  We also had no material impairment reserves on these loans at March 31, 2014 or December 31, 2013.
We assess our mortgage loans on a regular basis for credit impairments, and annually assign a credit quality indicator to each loan.  Our credit quality indicator is internally developed and categorizes our portfolio on a scale from 1 to 7.  Category 1 represents loans of superior quality, and Categories 6 and 7 represent loans where collections are at risk.  The vast majority of our mortgage loans fall into the Level 2 to 4 ratings.  These ratings represent loans where credit risk is minimal to acceptable; however, these loans may display some susceptibility to economic changes.  Category 5 represents loans where credit risk is not substantial but these loans warrant management’s close attention.  These indicators are based upon several factors, including current loan to value ratios, property condition, market trends, creditworthiness of the borrower and deal structure.  Based upon our most recent assessments at March 31, 2014 and December 31, 2013, our mortgage loans were given the following credit quality indicators:
(In Millions, except credit ratings indicator)	March 31,			December 31,
	2014			2013
1	$	68.3		$	69.2
2 to 4	1,399.00			1,399.60
5	30.2			30.6
6 and 7	50.1			50.2
Total	$	1,547.60		$	1,549.60
Variable Interest Entities
In determining whether to consolidate a variable interest entity (“VIE”), we consider several factors including whether we have the power to direct activities, the obligation to absorb losses and the right to receive benefits that could potentially be significant to the VIE.  We have relationships with certain real estate partnerships and one hedge fund partnership that are considered VIEs, but are not consolidated.  We record the amount of our investment in these partnerships as long-term investments on our balance sheets and recognize our share of partnership income or losses in earnings.  Our maximum exposure to loss as a result of our investment in these partnerships is our investment balance at March 31, 2014 and December 31, 2013 of approximately $208 million and $205 million, respectively, and the risk of recapture of tax credits related to the real estate partnerships previously recognized, which we do not consider significant.  We do not have a future obligation to fund losses or debts on behalf of these investments; however, we may voluntarily contribute funds.  The real estate partnerships construct, own and manage low-income housing developments and had total assets of approximately $5.4 billion and $5.8 billion at March 31, 2014 and December 31, 2013, respectively.  The hedge fund partnership had total assets of approximately $7.5 billion and $7.0 billion at March 31, 2014 and December 31, 2013, respectively.
Non-controlling (Minority) Interests
At March 31, 2014 and December 31, 2013, continuing business non-controlling interests were approximately $57 million and $53 million, respectively, primarily related to third party interests in our investment holdings as well as third party interests in certain of our operating entities. The non-controlling entities’ share was included in total equity. Net income attributable to non-controlling interests was $3.9 million and $.8 million for the three months ended March 31, 2014 and 2013, respectively. These non-controlling interests did not have a material impact on our financial position or operating results.
Net Investment Income
Sources of net investment income for the three months ended March 31, 2014 and 2013 were as follows:
(Millions)	2014			2013
Debt securities	$	198.1		$	188.8
Mortgage loans	23.9			24.8
Other investments	30.1			29.6
Gross investment income	252.1			243.2
Less: investment expenses	(7.9		)	(8.1		)
Net investment income (1)	$	244.2		$	235.1
(1)	Net investment income includes $80.4 million and $79.3 million for the three months ended March 31, 2014 and 2013, respectively, related to investments supporting our experience-rated and discontinued products.

Other_Comprehensive_Loss_Incom

Other Comprehensive (Loss) Income	3 Months Ended
	Mar. 31, 2014
Other Comprehensive Income (Loss), Net of Tax [Abstract]	'
Other Comprehensive (Loss) Income	'
	7.    Other Comprehensive (Loss) Income
	Shareholders’ equity included the following activity in accumulated other comprehensive loss for the three months ended March 31, 2014 and 2013:
		Net Unrealized Gains (Losses)															Pension and OPEB Plans										Total
																											Accumulated
																											Other
		Securities										Foreign															Comprehensive
												Currency															(Loss) Income
												and
	(Millions)	Previously					All Other					Derivatives			Unrecognized					Unrecognized
		Impaired (1)													Net Actuarial					Prior Service
															Losses					Credit
	Three months ended March 31, 2014
	Balance at December 31, 2013	$	34.2				$	326.8				$	0.4				$	(1,293.8	)			$	20.3				$	(912.1	)
	Other comprehensive income (loss)
	before reclassifications	1.1					137.2					(12.5		)			—					—					125.8
	Amounts reclassified from accumulated
	other comprehensive income	(.4		)	(2	)	3.3			(2	)	(10.1		)	(3	)	7.7			(4	)	(.6		)	(4	)	(.1		)
	Other comprehensive income (loss)	0.7					140.5					(22.6		)			7.7					(.6		)			125.7
	Balance at March 31, 2014	$	34.9				$	467.3				$	(22.2	)			$	(1,286.1	)			$	19.7				$	(786.4	)
	Three months ended March 31, 2013
	Balance at December 31, 2012	$	57.3				$	825.2				$	(29.5	)			$	(1,909.4	)			$	23				$	(1,033.4	)
	Other comprehensive (loss) income
	before reclassifications	(9.4		)			(78.5		)			6.7					—					—					(81.2		)
	Amounts reclassified from accumulated
	other comprehensive income	3.7			(2	)	(15.8		)	(2	)	0.8			(3	)	12.6			(4	)	(.6		)	(4	)	0.7
	Other comprehensive (loss) income	(5.7		)			(94.3		)			7.5					12.6					(.6		)			(80.5		)
	Balance at March 31, 2013	$	51.6				$	730.9				$	(22.0	)			$	(1,896.8	)			$	22.4				$	(1,113.9	)
	(1)	Represents unrealized gains on the non-credit related component of impaired debt securities that we do not intend to sell and subsequent changes in the fair value of any previously impaired security.
	(2)	Reclassifications out of accumulated other comprehensive income for previously impaired debt securities and all other securities are reflected in net realized capital gains (losses) within the Consolidated Statement of Income.
	(3)	Reclassifications out of accumulated other comprehensive income for foreign currency gains (losses) and derivatives are reflected in net realized capital gains (losses) within the Consolidated Statement of Income, except for the effective portion of derivatives related to interest rate swaps which are reflected in interest expense and were not material during the three months ended March 31, 2014 or 2013. Refer to Note 10 of Condensed Notes to Consolidated Financial Statements beginning on page 25 for additional information.
	(4)	Reclassifications out of accumulated other comprehensive income for pension and OPEB plan expenses are reflected in general and administrative expenses within the Consolidated Statement of Income. Refer to Note 9 of Condensed Notes to Consolidated Financial Statements beginning on page 24 for additional information.
	Refer to the Consolidated Statements of Comprehensive Income on page 2 for additional information regarding reclassifications out of accumulated other comprehensive income on a pretax basis.

Financial_Instruments

Financial Instruments	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Financial Instruments	'
	8.    Financial Instruments
	The preparation of our consolidated financial statements in accordance with GAAP requires certain of our assets and liabilities to be reflected at their fair value, and others on another basis, such as an adjusted historical cost basis.  In this note, we provide details on the fair value of financial assets and liabilities and how we determine those fair values.  We present this information for those financial instruments that are measured at fair value for which the change in fair value impacts net income attributable to Aetna or other comprehensive income separately from other financial assets and liabilities.
	Financial Instruments Measured at Fair Value in our Balance Sheets
	Certain of our financial instruments are measured at fair value in our balance sheets.  The fair values of these instruments are based on valuations that include inputs that can be classified within one of three levels of a hierarchy established by GAAP.  The following are the levels of the hierarchy and a brief description of the type of valuation information (“inputs”) that qualifies a financial asset or liability for each level:
	◦	Level 1 – Unadjusted quoted prices for identical assets or liabilities in active markets.
	◦	Level 2 – Inputs other than Level 1 that are based on observable market data.  These include: quoted prices for similar assets in active markets, quoted prices for identical assets in inactive markets, inputs that are observable that are not prices (such as interest rates and credit risks) and inputs that are derived from or corroborated by observable markets.
	◦	Level 3 – Developed from unobservable data, reflecting our own assumptions.
	Financial assets and liabilities are classified based upon the lowest level of input that is significant to the valuation.  When quoted prices in active markets for identical assets and liabilities are available, we use these quoted market prices to determine the fair value of financial assets and liabilities and classify these assets and liabilities as Level 1.  In other cases where a quoted market price for identical assets and liabilities in an active market is either not available or not observable, we estimate fair value using valuation methodologies based on available and observable market information or by using a matrix pricing model.  These financial assets and liabilities would then be classified as Level 2.  If quoted market prices are not available, we determine fair value using broker quotes or an internal analysis of each investment’s financial performance and cash flow projections.  Thus, financial assets and liabilities may be classified as Level 3 even though there may be some significant inputs that may be observable.
	The following is a description of the valuation methodologies used for our financial assets and liabilities that are measured at fair value, including the general classification of such assets and liabilities pursuant to the valuation hierarchy.
	Debt Securities – Where quoted prices are available in an active market, our debt securities are classified in Level 1 of the fair value hierarchy.  Our Level 1 debt securities are comprised primarily of U.S. Treasury securities.  If Level 1 valuations are not available, the fair value is determined using models such as matrix pricing, which use quoted market prices of debt securities with similar characteristics, or discounted cash flows to estimate fair value.  We obtained one price for each of our Level 2 debt securities and did not adjust any of these prices at March 31, 2014 or December 31, 2013.
	We also value certain debt securities using Level 3 inputs.  For Level 3 debt securities, fair values are determined by outside brokers or, in the case of certain private placement securities, are priced internally.  Outside brokers determine the value of these debt securities through a combination of their knowledge of the current pricing environment and market flows.  We obtained one non-binding broker quote for each of these Level 3 debt securities and did not adjust any of these quotes at March 31, 2014 or December 31, 2013.  The total fair value of our broker quoted debt securities was approximately $101 million at March 31, 2014 and $103 million at December 31, 2013.  Examples of these broker quoted Level 3 debt securities include certain U.S. and foreign corporate securities and certain of our commercial mortgage-backed securities as well as other asset-backed securities.  For some of our private placement securities, our internal staff determines the value of these debt securities by analyzing spreads of corporate and sector indices as well as interest spreads of comparable public bonds.  Examples of these private placement Level 3 debt securities include certain U.S. and foreign securities and certain tax-exempt municipal securities.
	Equity Securities – We currently have two classifications of equity securities:  those that are publicly traded and those that are privately held.  Our publicly-traded securities are classified as Level 1 because quoted prices are available for these securities in an active market.  For privately-held equity securities, there is no active market; therefore, we classify these securities as Level 3 because we price these securities through an internal analysis of each investment’s financial statements and cash flow projections. Significant unobservable inputs consist of earnings and revenue multiples, discount for lack of marketability and comparability adjustments. An increase or decrease in any of these unobservable inputs would result in a change in the fair value measurement, which may be significant.
	Derivatives – Where quoted prices are available in an active market, our derivatives are classified as Level 1.  Certain of our derivative instruments are valued using models that primarily use market observable inputs and therefore are classified as Level 2 because they are traded in markets where quoted market prices are not readily available.
	Financial assets and liabilities measured at fair value on a recurring basis in our balance sheets at March 31, 2014 and December 31, 2013 were as follows:
	(Millions)	Level 1			Level 2				Level 3				Total
	March 31, 2014
	Assets:
	Debt securities:
	U.S. government securities	$	1,169.30		$	232.8			$	—			$	1,402.10
	States, municipalities and political subdivisions	—			4,185.40				1.2				4,186.60
	U.S. corporate securities	—			8,199.30				42.9				8,242.20
	Foreign securities	—			3,456.90				28.3				3,485.20
	Residential mortgage-backed securities	—			963.1				—				963.1
	Commercial mortgage-backed securities	—			1,462.80				7.5				1,470.30
	Other asset-backed securities	—			306.3				37.4				343.7
	Redeemable preferred securities	—			62.4				4.1				66.5
	Total debt securities	1,169.30			18,869.00				121.4				20,159.70
	Equity securities	37.4			—				23.1				60.5
	Derivatives	—			0.4				—				0.4
	Total	$	1,206.70		$	18,869.40			$	144.5			$	20,220.60
	Liabilities:
	Derivatives	$	—		$	3.6			$	—			$	3.6
	December 31, 2013
	Assets:
	Debt securities:
	U.S. government securities	$	1,237.50		$	225			$	—			$	1,462.50
	States, municipalities and political subdivisions	—			4,161.00				1.3				4,162.30
	U.S. corporate securities	—			7,911.40				31.2				7,942.60
	Foreign securities	—			3,311.60				43.9				3,355.50
	Residential mortgage-backed securities	—			924.2				—				924.2
	Commercial mortgage-backed securities	—			1,399.50				7.5				1,407.00
	Other asset-backed securities	—			317.3				32.3				349.6
	Redeemable preferred securities	—			61.3				4.1				65.4
	Total debt securities	1,237.50			18,311.30				120.3				19,669.10
	Equity securities	17.1			—				44.2				61.3
	Derivatives	—			49.1				—				49.1
	Total	$	1,254.60		$	18,360.40			$	164.5			$	19,779.50
	Liabilities:
	Derivatives	$	—		$	1.9			$	—			$	1.9
	There were no transfers between Levels 1 and 2 during the three months ended March 31, 2014 or 2013.
	Gross transfers out of Level 3 during the three months ended March 31, 2014 and 2013 were $9.7 million and $8.0 million, respectively. Gross transfers out of Level 3 during the three months ended March 31, 2014 were primarily related to foreign debt securities. Gross transfers out of Level 3 during the three months ended March 31, 2013 were primarily related to U.S. corporate securities. The fair value of securities transferred out of Level 3 had been based on broker quotes and effective in the first quarter of both 2014 and 2013 is based primarily on a matrix pricing model, which uses quoted market prices of debt securities with similar characteristics. There were no transfers into Level 3 during the three months ended March 31, 2014 or 2013.
	Financial Instruments Not Measured at Fair Value in our Balance Sheets
	The following is a description of the valuation methodologies used for estimating the fair value of our financial assets and liabilities that are carried on our balance sheets at adjusted cost or contract value.
	Mortgage loans:  Fair values are estimated by discounting expected mortgage loan cash flows at market rates that reflect the rates at which similar loans would be made to similar borrowers.  These rates reflect our assessment of the credit worthiness of the borrower and the remaining duration of the loans.  The fair value estimates of mortgage loans of lower credit quality, including problem and restructured loans, are based on the estimated fair value of the underlying collateral.
	Bank loans: Where fair value is determined by quoted market prices of bank loans with similar characteristics, our bank loans are classified as Level 2. For bank loans classified as Level 3, fair value is determined by outside brokers using their internal analyses through a combination of their knowledge of the current pricing environment and market flows.
	Investment contract liabilities:
	•With a fixed maturity:  Fair value is estimated by discounting cash flows at interest rates currently
	being offered by, or available to, us for similar contracts.
	•Without a fixed maturity:  Fair value is estimated as the amount payable to the contract holder upon
	demand.  However, we have the right under such contracts to delay payment of withdrawals that
	may ultimately result in paying an amount different than that determined to be payable on demand.
	Long-term debt:  Fair values are based on quoted market prices for the same or similar issued debt or, if no quoted market prices are available, on the current rates estimated to be available to us for debt of similar terms and remaining maturities.
	The carrying value and estimated fair value classified by level of fair value hierarchy for certain of our financial instruments at March 31, 2014 and December 31, 2013 were as follows:
	Carrying			Estimated Fair Value
(Millions)	Value			Level 1			Level 2			Level 3			Total
March 31, 2014
Assets:
Mortgage loans	$	1,547.60		$	—		$	—		$	1,595.20		$	1,595.20
Bank loans	209.6			—			198.9			10.1			209
Liabilities:
Investment contract liabilities:
With a fixed maturity	8.9			—			—			8.9			8.9
Without a fixed maturity	557.1			—			—			545.1			545.1
Long-term debt	8,238.60			—			8,792.20			—			8,792.20
December 31, 2013
Assets:
Mortgage loans	$	1,549.60		$	—		$	—		$	1,584.80		$	1,584.80
Bank loans	181.7			—			171.5			9.8			181.3
Liabilities:
Investment contract liabilities:
With a fixed maturity	8.9			—			—			8.9			8.9
Without a fixed maturity	572.3			—			—			553.2			553.2
Long-term debt	8,252.60			—			8,670.60			—			8,670.60
Separate Accounts Measured at Fair Value in our Balance Sheets
Separate Accounts assets in our Large Case Pensions business represent funds maintained to meet specific objectives of contract holders.  Since contract holders bear the investment risk of these assets, a corresponding Separate Accounts liability has been established equal to the assets.  These assets and liabilities are carried at fair value.  Net investment income and capital gains and losses accrue directly to such contract holders.  The assets of each account are legally segregated and are not subject to claims arising from our other businesses.  Deposits, withdrawals, net investment income and realized and unrealized capital gains and losses on Separate Accounts assets are not reflected in our statements of income, shareholders’ equity or cash flows.
Separate Accounts assets include debt and equity securities and derivative instruments.  The valuation methodologies used for these assets are similar to the methodologies described beginning on page 18.  Separate Accounts assets also include investments in common/collective trusts that are carried at fair value. Common/collective trusts invest in other investment funds otherwise known as the underlying funds. The Separate Accounts’ interests in the common/collective trust funds are based on the fair values of the investments of the underlying funds and therefore are classified as Level 2. The assets in the underlying funds primarily consist of equity securities. Investments in common/collective trust funds are valued at their respective net asset value per share/unit on the valuation date.
Separate Accounts financial assets at March 31, 2014 and December 31, 2013 were as follows:
	March 31, 2014														December 31, 2013
(Millions)	Level 1			Level 2				Level 3				Total			Level 1		Level 2		Level 3		Total
Debt securities	$	753.3		$	2,245.70			$	1			$	3,000.00		$	726.4	$	2,227.00	$	0.6	$	2,954.00
Equity securities	189.5			4.5				—				194			188.4		3.3		—		191.7
Derivatives	—			0.7				—				0.7			—		0.8		—		0.8
Common/collective trusts	—			729.7				—				729.7			—		710.4		—		710.4
Total (1)	$	942.8		$	2,980.60			$	1			$	3,924.40		$	914.8	$	2,941.50	$	0.6	$	3,856.90
(1)	Excludes $255.3 million and $115.6 million of cash and cash equivalents and other receivables at March 31, 2014 and December 31, 2013, respectively.
During the three months ended March 31, 2014 and 2013, we had an immaterial amount of Level 3 Separate Accounts financial assets. There were no gross transfers of Separate Accounts financial assets out of Level 3 during the three months ended March 31, 2014. Gross transfers of Separate Accounts financial assets out of Level 3 during the three months ended March 31, 2013 were $.4 million. For the three months ended March 31, 2014 and 2013, there were no transfers of Separate Accounts financial assets between Levels 1 and 2 and no transfers of Separate Accounts financial assets into Level 3.
Offsetting Financial Assets and Liabilities
Certain financial assets and liabilities are offset in our balance sheets or are subject to master netting arrangements or similar agreements with the applicable counterparty. Financial assets, including derivative assets, subject to offsetting and enforceable master netting arrangements as of March 31, 2014 and December 31, 2013 were as follows:
	Gross Amounts of Recognized Assets (1)		Gross Amounts Not Offset
			in the Balance Sheets
			Financial Instruments			Cash Collateral Received
(Millions)									Net Amount
31-Mar-14
Derivatives	$	0.4	$	11.3		$	(.2	)	$	11.5
Total	$	0.4	$	11.3		$	(.2	)	$	11.5
31-Dec-13
Derivatives	$	49.1	$	13.3		$	(47.1	)	$	15.3
Total	$	49.1	$	13.3		$	(47.1	)	$	15.3
(1) There were no amounts offset in our balance sheets at March 31, 2014 or December 31, 2013.
Financial liabilities, including derivative liabilities, subject to offsetting and enforceable master netting arrangements as of March 31, 2014 and December 31, 2013 were as follows:
	Gross Amounts of Recognized Liabilities (1)		Gross Amounts Not Offset
			in the Balance Sheets
			Financial Instruments			Cash Collateral Paid
(Millions)									Net Amount
31-Mar-14
Derivatives	$	3.6	$	—		$	(4.9	)	$	(1.3	)
Securities lending	720.8		(720.7		)	—			0.1
Repurchase agreements	156.2		—			—			156.2
Total	$	880.6	$	(720.7	)	$	(4.9	)	$	155
31-Dec-13
Derivatives	$	1.9	$	—		$	(.7	)	$	1.2
Securities lending	792.6		(792.6		)	—			—
Total	$	794.5	$	(792.6	)	$	(.7	)	$	1.2
(1) There were no amounts offset in our balance sheets at March 31, 2014 or December 31, 2013.

Pension_and_Other_Postretireme

Pension and Other Postretirement Plans	3 Months Ended
	Mar. 31, 2014
Compensation and Retirement Disclosure [Abstract]	'
Pension and Other Postretirement Plans	'
	9.    Pension and Other Postretirement Plans
	Defined Benefit Retirement Plans
	Components of the net periodic benefit (income) cost of our defined benefit pension plans and other postretirement employee benefit (“OPEB”) plans for the three months ended March 31, 2014 and 2013 were as follows:
		Pension Plans						OPEB Plans
	(Millions)	2014			2013			2014			2013
	Service cost	$	—		$	—		$	—		$	—
	Amortization of prior service credit	(.1		)	(.1		)	(.9		)	(.9		)
	Interest cost	72.1			67.9			3			2.8
	Expected return on plan assets	(105.6		)	(99.1		)	(.8		)	(.6		)
	Recognized net actuarial losses	11.7			18.9			0.2			0.5
	Net periodic benefit (income) cost	$	(21.9	)	$	(12.4	)	$	1.5		$	1.8

Debt

Debt	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Debt Disclosure	'
	10.    Debt
	The carrying value of our long-term debt at March 31, 2014 and December 31, 2013 was as follows:
	(Millions)	March 31,		December 31,
		2014		2013
	Senior notes, 6.3%, due 2014	$	382.4	$	387.3
	Senior notes, 6.125%, due 2015	237.8		240.6
	Senior notes, 6.0%, due 2016	—		748.9
	Senior notes, 5.95%, due 2017	430.2		434.2
	Senior notes, 1.75%, due 2017	249		248.9
	Senior notes, 1.5%, due 2017	498.3		498.2
	Senior notes, 6.5%, due 2018	495		494.9
	Senior notes, 2.2%, due 2019	374.6		—
	Senior notes, 3.95%, due 2020	744.5		744.3
	Senior notes, 5.45%, due 2021	698.9		702.3
	Senior notes, 4.125%, due 2021	495		494.8
	Senior notes, 2.75%, due 2022	985.5		985.1
	Senior notes, 6.625%, due 2036	769.8		769.8
	Senior notes, 6.75%, due 2037	530.6		530.6
	Senior notes, 4.5%, due 2042	480.2		480.1
	Senior notes, 4.125%, due 2042	492.7		492.6
	Senior notes, 4.75%, due 2044	374.1		—
	Total long-term debt	8,238.60		8,252.60
	Less current portion of long-term debt (1)	620.2		387.3
	Total long-term debt, less current portion	$	7,618.40	$	7,865.30
	-1	At March 31, 2014, our 6.125% senior notes due January 2015 and 6.3% senior notes due August 2014 are classified as current in the accompanying consolidated balance sheet.
	At both March 31, 2014 and December 31, 2013 we did not have any commercial paper outstanding.
	Long-Term Debt and Interest Rate Swaps
	On February 7, 2014, we announced the redemption for cash of the entire $750 million aggregate principal amount outstanding of our 6.0% senior notes due 2016. The redemption of these notes occurred on March 14, 2014 (the “Redemption Date”) at a redemption price that included a make-whole premium, plus interest accrued and unpaid at the Redemption Date. We financed the redemption by issuing $375 million of 2.2% senior notes due 2019 and $375 million of 4.75% senior notes due 2044 (collectively, the “2014 Senior Notes”), together with other available resources. As a result of the redemption, in the first quarter of 2014, we recorded a loss on the early extinguishment of long-term debt of $59.7 million ($91.9 million pretax).
	During June and July 2012, we entered into two interest rate swaps with an aggregate notional value of $375 million. We designated these swaps as cash flow hedges against interest rate exposure related to the forecasted future issuance of fixed-rate debt to refinance our 6.0% senior notes due 2016. In March 2014, prior to issuing the 2014 Senior Notes used to refinance our 6.0% senior notes due 2016, we terminated these swaps and received an aggregate of $34.2 million from the swap counterparties upon termination. We performed a final effectiveness test upon termination of these swaps and determined there was approximately $12 million pretax of ineffectiveness that arose due to the actual debt issuance date being earlier than forecasted. The ineffectiveness was recorded as a realized capital gain in the first quarter of 2014. The effective portion of the hedge gain of approximately $22 million pretax was recorded in accumulated other comprehensive loss, net of tax, and is being amortized as a reduction to interest expense over the first 20 semi-annual interest payments associated with the $375 million of 4.75% senior notes due 2044.
	In March 2014, we entered into two interest rate swaps with an aggregate notional value of $500 million. We designated these swaps as cash flow hedges against interest rate exposure related to the forecasted future issuance of fixed-rate debt, to be primarily used to refinance long-term debt maturing in 2017. At March 31, 2014, these interest rate swaps had a pretax fair value loss of $2.9 million, which was reflected net of tax in accumulated other comprehensive loss within shareholders' equity.
	In April 2014, we entered into an interest rate swap with a notional value of $250 million. We designated this swap as a cash flow hedge against interest rate exposure related to the forecasted future issuance of fixed-rate debt to be primarily used to refinance long-term debt maturing in 2018.
	Revolving Credit Facility
	On March 27, 2012, we entered into an unsecured $1.5 billion five-year revolving credit agreement (the “Credit Agreement”) with several financial institutions. On September 24, 2012, in connection with the acquisition of Coventry, we entered into a First Amendment (the “First Amendment”) to the Credit Agreement and also entered into an Incremental Commitment Agreement (the “Incremental Commitment”, and together with the First Amendment and the Credit Agreement, resulting in the “Facility”). The Facility is an unsecured $2.0 billion revolving credit agreement. Upon our agreement with one or more financial institutions, we may expand the aggregate commitments under the Facility to a maximum of $2.5 billion. The Facility also provides for the issuance of up to $200 million of letters of credit at our request, which count as usage of the available commitments under the Facility. In 2013, we extended the maturity date of the Facility by one year. On March 27, 2014, we extended the maturity date of the Facility by an additional year to March 27, 2019.
	Various interest rate options are available under the Facility.  Any revolving borrowings mature on the termination date of the Facility.  We pay facility fees on the Facility ranging from .070% to .150% per annum, depending upon our long-term senior unsecured debt rating.  The facility fee was .100% at March 31, 2014.  The Facility contains a financial covenant that requires us to maintain a ratio of total debt to consolidated capitalization as of the end of each fiscal quarter at or below 50%.  For this purpose, consolidated capitalization equals the sum of total shareholders’ equity, excluding any overfunded or underfunded status of our pension and OPEB plans and any net unrealized capital gains and losses, and total debt (as defined in the Facility).  We met this requirement at March 31, 2014.  There were no amounts outstanding under the Facility at any time during the three months ended March 31, 2014 or 2013.

Capital_Stock

Capital Stock	3 Months Ended
	Mar. 31, 2014
Class of Stock Disclosures [Abstract]	'
Capital Stock	'
	11.    Capital Stock
	On February 28, 2014 and September 27, 2013, our Board of Directors (our “Board”) authorized two separate share repurchase programs of our common stock of up to $1.0 billion and $750 million, respectively.  During the three months ended March 31, 2014, we repurchased approximately 7 million shares of common stock at a cost of approximately $465 million.  At March 31, 2014, we had remaining authorization to repurchase an aggregate of up to approximately $1.1 billion of common stock under the February 28, 2014 and September 27, 2013 programs.
	During the three months ended March 31, 2014 our Board declared the following cash dividend:
	Date Declared	Dividend Amount			Stockholders of	Date Paid/	Total Dividends
		Per Share			Record Date	To be Paid	(Millions)
	February 28, 2014		$	0.225	April 10, 2014	April 25, 2014		$	80.5
	Declaration and payment of future dividends is at the discretion of our Board and may be adjusted as business needs or market conditions change.
	On March 3, 2014, approximately .4 million PSUs, .5 million MSUs, 1.0 million restricted stock units (“RSUs”) and 1.3 million SARs were granted to certain employees.  The number of vested PSUs (which could range from zero to 200% of the original number of units granted) is dependent upon the degree to which we achieve a certain operating performance goal, as determined by our Board’s Committee on Compensation and Talent Management, during a two-year performance period which began January 1, 2014 and ends on December 31, 2015.  The vesting period for the PSUs ends on March 3, 2017. The number of vested MSUs (which could range from zero to 150% of the original number of units granted) is based on the percentage change between the closing price of our common stock on the grant date and the weighted average closing price of our common stock for the thirty trading days prior to and including the vesting date.  The vesting period for the MSUs ends March 3, 2017. Each vested PSU, MSU and RSU represents one share of common stock and will be paid in shares of common stock, net of taxes, at the end of the applicable vesting period.  The RSUs generally will become 100% vested approximately three years from the grant date, with one-third vesting each December. The SARs, if exercised by the employee, will be settled in common stock, net of taxes, based on the appreciation of our common stock price over $72.26 per share, the closing price of our common stock on the grant date. SARs will become 100% vested approximately three years from the grant date, with one-third vesting on each anniversary of the grant date.
	In 2014, we granted SARs with an estimated fair market value of $22.68 per unit. The fair value per unit was calculated on the grant date using a Black-Scholes option pricing model using the following assumptions:
	Expected term (in years)	5.72
	Expected volatility	35.8		%
	Risk-free interest rate	1.74		%
	Dividend yield	1.36		%
	Initial price	$	72.26
	The expected term is based on historical equity award activity. Expected volatility is based on a weighted average of the historical volatility of our stock price and implied volatility from traded options on our stock. The risk-free interest rate is based on a U.S. Treasury rate with a life equal to the expected life of the SARs grant. This rate was calculated by interpolating between the 5-year and 10-year U.S. Treasury rates. The dividend yield is based on our historical dividends declared in the 12 months prior to the grant date.

Dividend_Restrictions_and_Stat

Dividend Restrictions and Statutory Surplus	3 Months Ended
	Mar. 31, 2014
Dividend Restrictions and Statutory Surplus [Abstract]	'
Dividend Restrictions and Statutory Surplus	'
	12.    Dividend Restrictions and Statutory Surplus
	Under applicable regulatory requirements at March 31, 2014, the amount of dividends that may be paid through the end of 2014 by our insurance and HMO subsidiaries without prior approval by regulatory authorities is approximately $1.5 billion in the aggregate. There are no such regulatory restrictions on distributions from Aetna to its shareholders. During the first quarter of 2014, our insurance and HMO subsidiaries paid approximately $235 million of dividends to the Company.
	The combined statutory capital and surplus of our insurance and HMO subsidiaries was $8.2 billion and $8.4 billion at March 31, 2014 and December 31, 2013, respectively.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	13.    Commitments and Contingencies
	Litigation and Regulatory Proceedings
	Out-of-Network Benefit Proceedings
	We are named as a defendant in several purported class actions and individual lawsuits arising out of our practices related to the payment of claims for services rendered to our members by health care providers with whom we do not have a contract (“out-of-network providers”).   Among other things, these lawsuits allege that we paid too little to our health plan members and/or providers for these services, among other reasons, because of our use of data provided by Ingenix, Inc., a subsidiary of one of our competitors (“Ingenix”). Other major health insurers are the subject of similar litigation or have settled similar litigation.
	Various plaintiffs who are health care providers or medical associations seek to represent nationwide classes of out-of-network providers who provided services to our members during the period from 2001 to the present.  Various plaintiffs who are members in our health plans seek to represent nationwide classes of our members who received services from out-of-network providers during the period from 2001 to the present.  Taken together, these lawsuits allege that we violated state law, the Employee Retirement Income Security Act of 1974, as amended (“ERISA”), the Racketeer Influenced and Corrupt Organizations Act and federal antitrust laws, either acting alone or in concert with our competitors.  The purported classes seek reimbursement of all unpaid benefits, recalculation and repayment of deductible and coinsurance amounts, unspecified damages and treble damages, statutory penalties, injunctive and declaratory relief, plus interest, costs and attorneys’ fees, and seek to disqualify us from acting as a fiduciary of any benefit plan that is subject to ERISA.  Individual lawsuits that generally contain similar allegations and seek similar relief have been brought by health plan members and out-of-network providers.
	The first class action case was commenced on July 30, 2007.  The federal Judicial Panel on Multi-District Litigation (the “MDL Panel”) has consolidated these class action cases in the U.S. District Court for the District of New Jersey (the “New Jersey District Court”) under the caption In re: Aetna UCR Litigation, MDL No. 2020 (“MDL 2020”).   In addition, the MDL Panel has transferred the individual lawsuits to MDL 2020.  On May 9, 2011, the New Jersey District Court dismissed the physician plaintiffs from MDL 2020 without prejudice.  The New Jersey District Court’s action followed a ruling by the United States District Court for the Southern District of Florida (the “Florida District Court”) that the physician plaintiffs were enjoined from participating in MDL 2020 due to a prior settlement and release.  The United States Court of Appeals for the Eleventh Circuit has dismissed the physician plaintiffs' appeal of the Florida District Court’s ruling.
	On December 6, 2012, we entered into an agreement to settle MDL 2020. Under the terms of the proposed nationwide settlement, we would have been released from claims relating to our out-of-network reimbursement practices from the beginning of the applicable settlement class period through August 30, 2013. The settlement agreement did not contain an admission of wrongdoing. The medical associations were not parties to the settlement agreement.
	Under the settlement agreement, we would have paid up to $120 million to fund claims submitted by health plan members and health care providers who were members of the settlement classes. These payments also would have funded the legal fees of plaintiffs' counsel and the costs of administering the settlement. In connection with the proposed settlement, the Company recorded an after-tax charge to net income attributable to Aetna of approximately $78 million in the fourth quarter of 2012.
	The settlement agreement provided us the right to terminate the agreement under certain conditions related to settlement class members who opted out of the settlement. Based on a report provided to the parties by the settlement administrator, the conditions permitting us to terminate the settlement agreement were satisfied. On March 13, 2014, we notified the New Jersey District Court and plaintiffs' counsel that we were terminating the settlement agreement. Various legal and factual developments since the date of the settlement agreement led us to believe terminating the settlement agreement was in our best interests. We intend to vigorously defend ourselves against the claims brought by the plaintiffs. As a result of this termination, we released the reserve established in connection with the settlement agreement, net of amounts due to the settlement administrator, which reduced first quarter 2014 other general and administrative expenses by $67.0 million ($103.0 million pretax).
	We also have received subpoenas and/or requests for documents and other information from, and been investigated by, attorneys general and other state and/or federal regulators, legislators and agencies relating to our out-of-network benefit payment and administration practices.  It is reasonably possible that others could initiate additional litigation or additional regulatory action against us with respect to our out-of-network benefit payment and/or administration practices.
	CMS Actions
	The Centers for Medicare & Medicaid Services (“CMS”) regularly audits our performance to determine our compliance with CMS’s regulations and our contracts with CMS and to assess the quality of services we provide to Medicare beneficiaries.  CMS uses various payment mechanisms to allocate and adjust premium payments to our and other companies’ Medicare plans by considering the applicable health status of Medicare members as supported by information maintained and provided by health care providers.  We collect claim and encounter data from providers and generally rely on providers to appropriately code their submissions and document their medical records.  CMS pays increased premiums to Medicare Advantage plans and prescription drug program plans for members who have certain medical conditions identified with specific diagnosis codes.  Federal regulators review and audit the providers’ medical records to determine whether those records support the related diagnosis codes that determine the members’ health status and the resulting risk-adjusted premium payments to us.  In that regard, CMS has instituted risk adjustment data validation (“RADV”) audits of various Medicare Advantage plans, including certain of the Company's plans. The Office of Inspector General (the “OIG”) also is auditing risk adjustment data of other companies, and we expect CMS and the OIG to continue auditing risk adjustment data.
	CMS is using a different audit methodology for RADV audits to determine refunds payable by Medicare Advantage plans for contract year 2011 and forward. Under this methodology, among other things, CMS will project the error rate identified in the audit sample of approximately 200 members to all risk adjusted premium payments made under the contract being audited.  Historically, CMS did not project sample error rates to the entire contract.  As a result, the new methodology may increase our exposure to premium refunds to CMS due to incomplete medical records maintained by providers.  During 2013, CMS selected certain of our Medicare Advantage contracts for contract year 2011 for audit.  We are currently unable to predict which of our Medicare Advantage contracts will be selected for future audit, the amounts of any retroactive refunds of, or prospective adjustments to, Medicare Advantage premium payments made to us, the effect of any such refunds or adjustments on the actuarial soundness of our Medicare Advantage bids, or whether any RADV audit findings would cause a change to our method of estimating future premium revenue in future bid submissions to CMS or compromise premium assumptions made in our bids for prior contract years or the current contract year.  Any premium or fee refunds or adjustments resulting from regulatory audits, whether as a result of RADV or other audits by CMS, the OIG or otherwise, could be material and could adversely affect our operating results, financial position and cash flows.
	Other Litigation and Regulatory Proceedings
	We are involved in numerous other lawsuits arising, for the most part, in the ordinary course of our business operations, including claims of or relating to bad faith, medical malpractice, non-compliance with state and federal regulatory regimes, marketing misconduct, failure to timely or appropriately pay or administer claims and benefits in our Health Care and Group Insurance businesses (including our post-payment audit and collection practices and reductions in payments to providers due to sequestration), provider network structure (including the use of performance-based networks and termination of provider contracts), rescission of insurance coverage, improper disclosure of personal information, patent infringement and other intellectual property litigation, other legal proceedings in our Health Care and Group Insurance businesses and employment litigation.  Some of these other lawsuits are or are purported to be class actions.  We intend to vigorously defend ourselves against the claims brought in these matters.
	Awards to us and others of certain government contracts, particularly in our Medicaid business, are subject to increasingly frequent protests by unsuccessful bidders. These protests may result in awards to us being reversed, delayed or modified. The loss or delay in implementation of any government contract could adversely affect our operating results. We will continue to defend vigorously contract awards we receive.
	In addition, our operations, current and past business practices, current and past contracts, and accounts and other books and records are subject to routine, regular and special investigations, audits, examinations and reviews by, and from time to time we receive subpoenas and other requests for information from, CMS, the U.S. Department of Health and Human Services, various state insurance and health care regulatory authorities, state attorneys general and offices of inspector general, the Center for Consumer Information and Insurance Oversight, OIG, the Office of Personnel Management, the U.S. Department of Labor, committees, subcommittees and members of the U.S. Congress, the U.S. Department of Justice, the Federal Trade Commission, U.S. attorneys and other state, federal and international governmental authorities.  These government actions include inquiries by, and testimony before, certain members, committees and subcommittees of the U.S. Congress regarding certain of our current and past business practices, including our overall claims processing and payment practices, our business practices with respect to our small group products, student health products or individual customers (such as market withdrawals, rating information, premium increases and medical benefit ratios), executive compensation matters and travel and entertainment expenses, as well as the investigations by, and subpoenas and requests from, attorneys general and others described above under “Out-of-Network Benefit Proceedings.”
	Over 35 states are investigating life insurers' claims payment and related escheat practices, and these investigations have resulted in significant charges to earnings by other life insurers in connection with related settlements. We have received requests for information from a number of states, and certain of our subsidiaries are being audited, with respect to our life insurance claim payment and related escheat practices.  In the fourth quarter of 2013, we made changes to our life insurance claim payment practices (including related escheatment practices) based on evolving industry practices and regulatory expectations and interpretations, including expanding our existing use of the Social Security Administration's Death Master File to identify additional potentially unclaimed death benefits and locate applicable beneficiaries. As a result of these changes, in the fourth quarter of 2013, we increased our estimated liability for unpaid life insurance claims with respect to insureds who passed away on or before December 31, 2013, and recorded in current and future benefits a charge of $35.7 million ($55.0 million pretax). Given the legal and regulatory uncertainty with respect to life insurance claim payment and related escheat practices, it is reasonably possible that we may incur additional liability related to those practices, whether as a result of further changes in our business practices, litigation, government actions or otherwise, which could adversely affect our operating results and cash flows.
	There also continues to be heightened review by regulatory authorities of, and increased litigation regarding, our and the rest of the health care and related benefits industry’s business and reporting practices, including premium rate increases, utilization management, development and application of medical policies, complaint, grievance and appeal processing, information privacy, provider network structure (including the use of performance-based networks and termination of provider contracts), delegated arrangements, rescission of insurance coverage, limited benefit health products, student health products, pharmacy benefit management practices, sales practices, and claim payment practices (including payments to out-of-network providers and payments on life insurance policies).
	As a leading national health and related benefits company, we regularly are the subject of government actions of the types described above.  These government actions may prevent or delay us from implementing planned premium rate increases and may result, and have resulted, in restrictions on our business, changes to or clarifications of our business practices, retroactive adjustments to premiums, refunds or other payments to members, beneficiaries, states or the federal government, assessments of damages, civil or criminal fines or penalties, or other sanctions, including the possible loss of licensure or suspension or exclusion from participation in government programs.
	Estimating the probable losses or a range of probable losses resulting from litigation, government actions and other legal proceedings is inherently difficult and requires an extensive degree of judgment, particularly where the matters involve indeterminate claims for monetary damages, may involve fines, penalties or punitive damages that are discretionary in amount, involve a large number of claimants or regulatory authorities, represent a change in regulatory policy, present novel legal theories, are in the early stages of the proceedings, are subject to appeal or could result in a change in business practices.  In addition, because most legal proceedings are resolved over long periods of time, potential losses are subject to change due to, among other things, new developments, changes in litigation strategy, the outcome of intermediate procedural and substantive rulings and other parties’ settlement posture and their evaluation of the strength or weakness of their case against us. Except as specifically noted above under “Other Litigation and Regulatory Proceedings,” we are currently unable to predict the ultimate outcome of, or reasonably estimate the losses or a range of losses resulting from, the matters described above, and it is reasonably possible that their outcome could be material to us.

Segment_Information

Segment Information	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Segment Information	'
	14.    Segment Information
	Our operations are conducted in three business segments:  Health Care, Group Insurance and Large Case Pensions.  The acquired Coventry operations are reflected in our Health Care segment for the three months ended March 31, 2014. Our Corporate Financing segment is not a business segment; it is added to our business segments to reconcile to our consolidated results.  The Corporate Financing segment includes interest expense on our outstanding debt and the financing components of our pension and OPEB plan expense (the service cost and prior service cost components of this expense are allocated to our business segments). Non-GAAP financial measures we disclose, such as operating earnings, should not be considered a substitute for, or superior to, financial measures determined or calculated in accordance with GAAP.
	Summarized financial information of our segments for the three months ended March 31, 2014 and 2013 were as follows:
	(Millions)	Health			Group			Large Case		Corporate			Total Company
		Care			Insurance			Pensions		Financing
	Three Months Ended March 31, 2014
	Revenue from external customers	$	13,131.40		$	544.4		$	46.3	$	—		$	13,722.10
	Operating earnings (loss) (1)	719			41.2			4.8		(43.0		)	722
	Three Months Ended March 31, 2013
	Revenue from external customers	$	8,723.20		$	505.3		$	45	$	—		$	9,273.50
	Operating earnings (loss) (1)	513.2			31.9			6.2		(34.8		)	516.5
	(1)	Operating earnings (loss) excludes net realized capital gains or losses, amortization of other acquired intangible assets and the other items described in the reconciliation below.
	A reconciliation of operating earnings (1) to net income attributable to Aetna for the three months ended March 31, 2014 and 2013 was as follows:
	(Millions)	2014			2013
	Operating earnings (1)	$	722		$	516.5
	Transaction and integration-related costs, net of tax	(41.9		)	(24.6		)
	Loss on early extinguishment of long-term debt, net of tax	(59.7		)	—
	Release of litigation-related reserve, net of tax	67			—
	Amortization of other acquired intangible assets, net of tax	(40.4		)	(21.1		)
	Net realized capital gains, net of tax	18.5			19.3
	Net income attributable to Aetna	$	665.5		$	490.1
	(1)	In addition to net realized capital gains (losses) and amortization of other acquired intangible assets, the following other items are excluded from operating earnings because we believe they neither relate to the ordinary course of our business nor reflect our underlying business performance:
	•	We incurred transaction and integration-related costs of $41.9 million ($63.7 million pretax) and $24.6 million ($37.1 million pretax) during the three months ended March 31, 2014 and 2013, respectively, related to the acquisition of Coventry. Transaction costs include advisory, legal and other professional fees which are not deductible for tax purposes and are reflected in our GAAP Consolidated Statements of Income in general and administrative expenses. Transaction costs also include transaction-related payments as well as expenses related to the negative cost of carry associated with the permanent financing that we obtained in November 2012 for the Coventry acquisition. Prior to the Effective Date, the negative cost of carry was excluded from operating earnings. The components of the negative cost of carry are reflected in our GAAP Consolidated Statements of Income in interest expense, net investment income, and general and administrative expenses. On and after the Effective Date, the interest expense and general and administrative expenses associated with the permanent financing are no longer excluded from operating earnings.
	•	In the first quarter of 2014, we incurred a loss on the early extinguishment of long-term debt of $59.7 million ($91.9 million pretax) related to the redemption of our 6.0% senior notes due 2016.
	•	In the fourth quarter of 2012, we recorded a charge of $78.0 million ($120.0 million pretax) related to the settlement of purported class action litigation regarding our payment practices related to out-of-network health care providers. That charge included the estimated cost of legal fees of plaintiffs' counsel and the costs of administering the settlement. In the first quarter of 2014, we exercised our right to terminate the settlement agreement. As a result, we released the reserve established in connection with the settlement agreement, net of amounts due to the settlement administrator, which reduced first quarter 2014 other general and administrative expenses by $67.0 million ($103.0 million pretax). Refer to Note 13 beginning on page 27 for additional information on the termination of the settlement agreement.

Reinsurance

Reinsurance	3 Months Ended
	Mar. 31, 2014
Reinsurance Disclosures [Abstract]	'
Reinsurance	'
	15.     Reinsurance
	In January 2014, we entered into five-year reinsurance agreements with Vitality Re V Limited, an unrelated insurer. The agreements allow us to reduce our required capital and provide $200 million of collateralized excess of loss reinsurance coverage on a portion of Aetna's group Commercial Insured Health Care business. The Company's similar reinsurance agreements with Vitality Re Limited and Vitality Re II Limited expired in January 2014.

Discontinued_Products

Discontinued Products	3 Months Ended
	Mar. 31, 2014
Discontinued Products [Abstract]	'
Discontinued Products	'
	16	Discontinued Products
	Prior to 1993, we sold single-premium annuities (“SPAs”) and guaranteed investment contracts (“GICs”), primarily to employer sponsored pension plans.  In 1993, we discontinued selling these products to Large Case Pensions customers, and now we refer to these products as discontinued products.
	We discontinued selling these products because they were generating losses for us, and we projected that they would continue to generate losses over their life (which is currently greater than 30 years for SPAs); so we established a reserve for anticipated future losses at the time of discontinuance.  This reserve represents the present value (at the risk-free rate of return at the time of discontinuance, consistent with the duration of the liabilities) of the difference between the expected cash flows from the assets supporting these products and the cash flows expected to be required to meet the obligations of the outstanding contracts.  At both March 31, 2014 and December 31, 2013, our remaining GIC liability was not material.
	Key assumptions in setting the reserve for anticipated future losses include future investment results, payments to retirees, mortality and retirement rates and the cost of asset management and customer service.  In 2012, we modified the mortality tables used in order to reflect a more up-to-date 2000 Retired Pensioner’s Mortality table. The mortality tables were previously modified in 1995, in order to reflect a more up-to-date 1994 Uninsured Pensioner's Mortality table. In 1997, we began the use of a bond default assumption to reflect historical default experience.  Other than these changes, since 1993 there have been no significant changes to the assumptions underlying the reserve.
	We review the adequacy of this reserve quarterly based on actual experience.  As long as our expected future losses remain consistent with prior projections, the results of the discontinued products are applied against the reserve and do not impact net income attributable to Aetna.  If actual or expected future losses are greater than we currently estimate, we may increase the reserve, which could adversely impact net income attributable to Aetna.  If actual or expected future losses are less than we currently estimate, we may decrease the reserve, which could favorably impact net income attributable to Aetna.  The reserve at each of March 31, 2014 and December 31, 2013 reflects management's best estimate of anticipated future losses, and is included in future policy benefits on our balance sheet.
	The activity in the reserve for anticipated future losses on discontinued products for the three months ended March 31, 2014 and 2013 (pretax) was as follows:
	(Millions)	2014		2013
	Reserve, beginning of period	$	979.5	$	978.5
	Operating income	5.8		8.8
	Net realized capital gains	6.3		32.8
	Reserve, end of period	$	991.6	$	1,020.10
	During the three months ended March 31, 2014 and 2013, our discontinued products reflected operating income and net realized capital gains, primarily attributable to gains from the sale of debt securities. Net realized capital gains during the three months ended March 31, 2013 also reflected gains from the sale of other invested assets. We evaluated these results against the expectations of future cash flows assumed in estimating the reserve for anticipated future losses and did not believe that an adjustment to the reserve was required at March 31, 2014 or 2013.
	Assets and liabilities supporting discontinued products at March 31, 2014 and December 31, 2013 were as
	follows: (1)
	(Millions)	2014		2013
	Assets:
	Debt and equity securities available for sale	$	2,367.00	$	2,372.60
	Mortgage loans	420.9		407
	Other investments	685		663.9
	Total investments	3,472.90		3,443.50
	Other assets	86.6		85.2
	Collateral received under securities loan agreements	175		204.4
	Current and deferred income taxes	17.2		14.4
	Receivable from continuing products (2)	541.3		533.1
	Total assets	$	4,293.00	$	4,280.60
	Liabilities:
	Future policy benefits	$	2,765.30	$	2,804.80
	Reserve for anticipated future losses on discontinued products	991.6		979.5
	Collateral payable under securities loan agreements	175		204.4
	Other liabilities (3)	361.1		291.9
	Total liabilities	$	4,293.00	$	4,280.60
	(1)	Assets supporting the discontinued products are distinguished from assets supporting continuing products.
	(2)	At the time of discontinuance, a receivable from Large Case Pensions' continuing products was established on the discontinued products balance sheet. This receivable represented the net present value of anticipated cash shortfalls in the discontinued products, which will be funded from continuing products. Interest on the receivable is accrued at the discount rate that was used to calculate the reserve. The offsetting payable, on which interest is similarly accrued, is reflected in continuing products. Interest on the payable generally offsets investment income on the assets available to fund the shortfall. These amounts are eliminated in consolidation.
	(3)	Net unrealized capital gains on the available-for-sale debt securities are included in other liabilities and are not reflected in consolidated shareholders’ equity.
	The distributions on our discontinued products consisted of scheduled contract maturities, settlements and benefit payments of $97 million and $100 million for the three months ended March 31, 2014 and 2013, respectively. There were no participant-directed withdrawals from our discontinued products during the three months ended March 31, 2014 or 2013.  Cash required to fund these distributions was provided by earnings and scheduled payments on, and sales of, invested assets.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
Interim Financial Statements	'
	Interim Financial Statements
	These interim financial statements necessarily rely on estimates, including assumptions as to annualized tax rates.  In the opinion of management, all adjustments necessary for a fair statement of results for the interim periods have been made.  All such adjustments are of a normal, recurring nature.  The accompanying unaudited consolidated financial statements and related notes should be read in conjunction with the consolidated financial statements and related notes presented in our 2013 Annual Report on Form 10-K (our “2013 Annual Report”).  Certain financial information that is normally included in annual financial statements prepared in accordance with U.S. generally accepted accounting principles (“GAAP”), but that is not required for interim reporting purposes, has been condensed or omitted.  We have omitted certain footnote disclosures that would substantially duplicate the disclosures in our 2013 Annual Report, unless the information contained in those disclosures materially changed and is required by GAAP.  We evaluated subsequent events that occurred after March 31, 2014 through the date the financial statements were issued and determined there were no other items to disclose other than those disclosed in Notes 3 and 10 beginning on pages 8 and 25, respectively.
Principles of Consolidation	'
	Principles of Consolidation
	The accompanying unaudited consolidated financial statements have been prepared in accordance with GAAP and include the accounts of Aetna and the subsidiaries we control.  All significant intercompany balances have been eliminated in consolidation.
Reclassifications	'
	Reclassifications
	Certain reclassifications were made to 2013 financial information to conform with the 2014 presentation.
Health Care Reform	'
	Accounting for certain provisions of the Patient Protection and Affordable Care Act and the Health Care and Education Reconciliation Act of 2010 (collectively, “Health Care Reform” or “ACA”)
	We are participating in certain public health insurance exchanges established pursuant Health Care Reform. Under regulations established by the U.S. Department of Health and Human Services (“HHS”), HHS pays us a portion of the premium (“Premium Subsidy”) and/or a portion of the health care costs (“Cost Sharing Subsidy”) for low-income individual members. In addition, HHS administers certain risk management programs as described below.
	We recognize monthly premiums received from members and the Premium Subsidy as premium revenue ratably over the contract period. The Cost Sharing Subsidy offsets health care costs when incurred. We record a liability if the Cost Sharing Subsidy is paid in advance or a receivable if incurred health care costs exceed the Cost Sharing Subsidy received to date.
	Accounting for Health Care Reform's Reinsurance, Risk Adjustment and Risk Corridor (the “3Rs”)
	Reinsurance
	Health Care Reform established a temporary three-year reinsurance program, whereby all issuers of major medical commercial insurance products and self-insured plan sponsors are required to contribute funding in amounts set by HHS. Funds collected will be utilized to reimburse issuers' high claims costs incurred for qualified individual members. The expense related to this required funding is reflected in general and administrative expenses for all of our insurance products with the exception of products associated with qualified individual members; this expense for qualified individual members is reflected as a reduction of premium revenue. When annual claim costs incurred by our qualified individual members exceed a specified attachment point, we are entitled to certain reimbursements from this program. We record a receivable and offset health care costs to reflect our estimate of these recoveries.
	Risk Adjustment
	Health Care Reform established a permanent risk adjustment program to transfer funds from qualified individual and small group insurance plans with below average risk scores to those respective plans with above average risk scores. Based on the risk of our qualified plan members compared to the risk of members of other qualified plans in comparable markets, we estimate our ultimate 2014 risk adjustment receivable or payable and reflect the pro-rata year-to-date impact as an adjustment to our premium revenue.
	Risk Corridor
	Health Care Reform established a temporary three-year risk sharing program. Under this program we make (or receive) a payment to (or from) HHS based on the ratio of allowable costs to target costs (as defined by Health Care Reform). Risk corridor payments from HHS will be limited to the extent of the risk corridor collections received by HHS over the duration of the program. We record a risk corridor receivable or payable as an adjustment to premium revenue on a pro-rata year-to-date basis based on our estimate of the ultimate 2014 risk sharing amount.
	We will perform a final reconciliation and settlement with HHS of the 2014 Cost Sharing Subsidy and 3Rs in 2015.

Acquisitions_Completed_Disposi1

Acquisitions, Completed Disposition (Tables)	3 Months Ended
	Mar. 31, 2014
Business Acquisition [Line Items]	'
Business Acquisition, Pro Forma Information	'
	The following table presents supplemental pro forma information for the three months ended March 31, 2013, as if the Merger had occurred on January 1, 2012. The unaudited pro forma consolidated results are not necessarily indicative of what our consolidated results would have been had the Merger been completed on January 1, 2012. In addition, the unaudited pro forma consolidated results do not purport to project the future results of the combined company nor do they reflect the expected realization of any cost savings associated with the Merger.
		Three Months Ended
	(Millions, except per common share data)	31-Mar-13
	Total revenue	$	12,939.40
	Net income attributable to Aetna	638.6
	Earnings per share:
	Basic	$	1.69
	Diluted	1.67

Earnings_Per_Common_Share_Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	The computations of basic and diluted EPS for the three months ended March 31, 2014 and 2013 are as follows:
	(Millions, except per common share data)	2014			2013
	Net income attributable to Aetna	$	665.5		$	490.1
	Weighted average shares used to compute basic EPS	361.6			327.6
	Dilutive effect of outstanding stock-based compensation awards	3.4			3.1
	Weighted average shares used to compute diluted EPS	365			330.7
	Basic EPS	$	1.84		$	1.5
	Diluted EPS	$	1.82		$	1.48
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	'
	The stock-based compensation awards excluded from the calculation of diluted EPS for the three months ended March 31, 2014 and 2013 are as follows:
	(Millions)	2014		2013
	Stock appreciation rights ("SARs") (1)	1.3		6.7
	Market stock units ("MSUs") (2)	0.4		0.4
	Performance stock units ("PSUs") (2)	0.7		0.8
	Performance stock appreciation rights ("PSARs") (2)	0.2		—
	(1)	SARs are excluded from the calculation of diluted EPS if the exercise price is greater than the average market price of Aetna common shares during the period (i.e., the awards are anti-dilutive).
	(2)	PSUs, certain MSUs with performance conditions and PSARs are excluded from the calculation of diluted EPS if all necessary performance conditions have not been satisfied at the end of the reporting period.

Operating_Expenses_Tables

Operating Expenses (Tables)	3 Months Ended
	Mar. 31, 2014
Operating Expenses [Abstract]	'
Operating Expenses	'
	For the three months ended March 31, 2014 and 2013, selling expenses (which include broker commissions, the variable component of our internal sales force compensation and premium taxes) and general and administrative expenses were as follows:
	(Millions)	2014		2013
	Selling expenses	$	402.8	$	297.2
	General and administrative expenses:
	Salaries and related benefits	1,110.70		802.5
	Other general and administrative expenses  (1) (2) (3)	936.9		639.5
	Total general and administrative expenses	2,047.60		1,442.00
	Total operating expenses	$	2,450.40	$	1,739.20
	(1)	The three months ended March 31, 2014 include estimated ACA mandated fees comprised primarily of the HIF and our contribution to the funding of the reinsurance program of $154.8 million and $84.9 million, respectively. Refer to Note 2 beginning on page 6 for additional information on ACA mandated fees.
	(2)	The three months ended March 31, 2014 include $63.7 million of integration-related costs related to the acquisition of Coventry. The three months ended March 31, 2013 include $24.3 million of transaction and integration-related costs related to the acquisition of Coventry, including advisory, legal and other professional services fees and transaction-related payments.
	(3)	In the fourth quarter of 2012, we recorded a charge of $120.0 million pretax related to the settlement of purported class action litigation regarding Aetna's payment practices related to out-of-network health care providers. That charge included the estimated cost of legal fees of plaintiffs' counsel and the costs of administering the settlement. In the first quarter of 2014, we exercised our right to terminate the settlement agreement. As a result, we released the reserve established in connection with the settlement agreement, net of amounts due to the settlement administrator, which reduced first quarter 2014 other general and administrative expenses by $103.0 million pretax. Refer to Note 13 beginning on page 27 for additional information on the termination of the settlement agreement.

Investments_Tables

Investments (Tables)	3 Months Ended
	Mar. 31, 2014
Investments [Abstract]	'
Total investments	'
	Total investments at March 31, 2014 and December 31, 2013 were as follows:
		March 31, 2014										December 31, 2013
	(Millions)	Current			Long-term			Total				Current			Long-term		Total
	Debt and equity securities available for sale	$	2,121.00		$	18,099.20		$	20,220.20			$	1,977.40		$	17,753.00	$	19,730.40
	Mortgage loans	83.1			1,464.50			1,547.60				84.9			1,464.70		1,549.60
	Other investments	5.7			1,726.70			1,732.40				1.5			1,717.30		1,718.80
	Total investments	$	2,209.80		$	21,290.40		$	23,500.20			$	2,063.80		$	20,935.00	$	22,998.80
Debt and equity securities available for sale	'
	Debt and equity securities available for sale at March 31, 2014 and December 31, 2013 were as follows:
	(Millions)	Amortized			Gross			Gross					Fair
		Cost			Unrealized			Unrealized					Value
					Gains			Losses
	March 31, 2014
	Debt securities:
	U.S. government securities	$	1,325.40		$	77.8		$	(1.1	)			$	1,402.10
	States, municipalities and political subdivisions	4,043.10			182.9			(39.4		)			4,186.60
	U.S. corporate securities	7,725.40			572.3			(55.5		)			8,242.20
	Foreign securities	3,267.00			244.3			(26.1		)			3,485.20
	Residential mortgage-backed securities	960			18			(14.9		)			963.1
	Commercial mortgage-backed securities	1,389.40			84			(3.1		)	(1)		1,470.30
	Other asset-backed securities	336.7			8.2			(1.2		)	(1)		343.7
	Redeemable preferred securities	56.8			9.7			—					66.5
	Total debt securities	19,103.80			1,197.20			(141.3		)			20,159.70
	Equity securities	45.8			19.4			(4.7		)			60.5
	Total debt and equity securities (2)	$	19,149.60		$	1,216.60		$	(146.0	)			$	20,220.20
	December 31, 2013
	Debt securities:
	U.S. government securities	$	1,396.80		$	68.7		$	(3.0	)			$	1,462.50
	States, municipalities and political subdivisions	4,118.50			126.6			(82.8		)			4,162.30
	U.S. corporate securities	7,559.00			493.7			(110.1		)			7,942.60
	Foreign securities	3,209.60			198.9			(53.0		)			3,355.50
	Residential mortgage-backed securities	928.4			16.9			(21.1		)			924.2
	Commercial mortgage-backed securities	1,323.50			88.2			(4.7		)	(1)		1,407.00
	Other asset-backed securities	343.4			8.3			(2.1		)	(1)		349.6
	Redeemable preferred securities	56.8			8.6			—					65.4
	Total debt securities	18,936.00			1,009.90			(276.8		)			19,669.10
	Equity securities	38.5			26.5			(3.7		)			61.3
	Total debt and equity securities (2)	$	18,974.50		$	1,036.40		$	(280.5	)			$	19,730.40
	(1)	At March 31, 2014 and December 31, 2013, we held securities for which we previously recognized $18.6 million and $22.8 million, respectively, of non-credit related impairments in accumulated other comprehensive loss. These securities had a net unrealized capital gain at March 31, 2014 and December 31, 2013 of $5.4 million and $6.6 million, respectively.
	(2)	Investment risks associated with our experience-rated and discontinued products generally do not impact our operating results (refer to Note 16 beginning on page 32 for additional information on our accounting for discontinued products).  At March 31, 2014, debt and equity securities with a fair value of approximately $3.7 billion, gross unrealized capital gains of $348.8 million and gross unrealized capital losses of $28.6 million and, at December 31, 2013, debt and equity securities with a fair value of approximately $3.7 billion, gross unrealized capital gains of $291.3 million and gross unrealized capital losses of $60.3 million were included in total debt and equity securities, but support our experience-rated and discontinued products.  Changes in net unrealized capital gains (losses) on these securities are not reflected in accumulated other comprehensive income.
Fair value of debt securities by contractual maturity	'
	The fair value of debt securities at March 31, 2014 is shown below by contractual maturity.  Actual maturities may differ from contractual maturities because securities may be restructured, called or prepaid.
	(Millions)	Fair
		Value
	Due to mature:
	Less than one year	$	949.1
	One year through five years	5,424.20
	After five years through ten years	5,721.00
	Greater than ten years	5,288.30
	Residential mortgage-backed securities	963.1
	Commercial mortgage-backed securities	1,470.30
	Other asset-backed securities	343.7
	Total	$	20,159.70
Debt and Equity Securities in an Unrealized Capital Loss Position	'
	Summarized below are the debt and equity securities we held at March 31, 2014 and December 31, 2013 that were in an unrealized capital loss position, aggregated by the length of time the investments have been in that position:
		Less than 12 months						Greater than 12 months							Total (1)
	(Millions)	Fair			Unrealized			Fair				Unrealized			Fair		Unrealized
		Value			Losses			Value				Losses			Value		Losses
	March 31, 2014
	Debt securities:
	U.S. government securities	$	51.4		$	0.8		$	13.4			$	0.3		$	64.8	$	1.1
	States, municipalities and political subdivisions	1,136.10			31.5			155.7				7.9			1,291.80		39.4
	U.S. corporate securities	1,558.40			39.3			181.9				16.2			1,740.30		55.5
	Foreign securities	569.3			18.9			100.9				7.2			670.2		26.1
	Residential mortgage-backed securities	462.5			11.7			35				3.2			497.5		14.9
	Commercial mortgage-backed securities	183.2			2.7			24.9				0.4			208.1		3.1
	Other asset-backed securities	73.1			1.1			2				0.1			75.1		1.2
	Redeemable preferred securities	4.4			—			—				—			4.4		—
	Total debt securities	4,038.40			106			513.8				35.3			4,552.20		141.3
	Equity securities	—			—			15				4.7			15		4.7
	Total debt and equity securities (1)	$	4,038.40		$	106		$	528.8			$	40		$	4,567.20	$	146
	December 31, 2013
	Debt securities:
	U.S. government securities	$	555.9		$	2.7		$	13.4			$	0.3		$	569.3	$	3
	States, municipalities and political subdivisions	1,779.90			73.1			132.4				9.7			1,912.30		82.8
	U.S. corporate securities	2,196.80			88			170				22.1			2,366.80		110.1
	Foreign securities	875.2			43.5			90.9				9.5			966.1		53
	Residential mortgage-backed securities	541.1			17.3			35				3.8			576.1		21.1
	Commercial mortgage-backed securities	162.4			4.2			25				0.5			187.4		4.7
	Other asset-backed securities	87.8			1.9			7.7				0.2			95.5		2.1
	Redeemable preferred securities	4.4			—			—				—			4.4		—
	Total debt securities	6,203.50			230.7			474.4				46.1			6,677.90		276.8
	Equity securities	—			—			16.2				3.7			16.2		3.7
	Total debt and equity securities (1)	$	6,203.50		$	230.7		$	490.6			$	49.8		$	6,694.10	$	280.5
	(1)	At March 31, 2014 and December 31, 2013, debt and equity securities in an unrealized capital loss position of $28.6 million and $60.3 million, respectively, and with related fair value of $598.0 million and $1.0 billion, respectively, related to experience-rated and discontinued products.
Maturity dates for debt securities	'
	The maturity dates for debt securities in an unrealized capital loss position at March 31, 2014 were as follows:
		Supporting discontinued and						Supporting remaining							Total
		experience-rated products						products
	(Millions)	Fair			Unrealized			Fair				Unrealized			Fair		Unrealized
		Value			Losses			Value				Losses			Value		Losses
	Due to mature:
	Less than one year	$	—		$	—		$	38.9			$	0.8		$	38.9	$	0.8
	One year through five years	25.6			0.3			882.1				8.1			907.7		8.4
	After five years through ten years	244.3			7.7			1,457.40				43.3			1,701.70		51
	Greater than ten years	285.5			15.3			837.7				46.6			1,123.20		61.9
	Residential mortgage-backed securities	10.8			0.2			486.7				14.7			497.5		14.9
	Commercial mortgage-backed securities	8.9			0.3			199.2				2.8			208.1		3.1
	Other asset-backed securities	7.9			0.1			67.2				1.1			75.1		1.2
	Total	$	583		$	23.9		$	3,969.20			$	117.4		$	4,552.20	$	141.3
Net realized capital gains (losses)	'
	Net realized capital gains for the three months ended March 31, 2014 and 2013, excluding amounts related to experience-rated contract holders and discontinued products, were as follows:
	(Millions)	2014			2013
	OTTI losses on debt securities	$	(.2	)	$	(5.8	)
	Portion of OTTI losses on debt securities recognized	—			—
	in other comprehensive income
	Net OTTI losses on debt securities recognized in earnings	(.2		)	(5.8		)
	Net realized capital gains, excluding OTTI losses on debt securities	28.7			36.1
	Net realized capital gains	$	28.5		$	30.3
Proceeds and related gross realized capital gains and losses from the sale of debt securities	'
	Excluding amounts related to experience-rated and discontinued products, proceeds from the sale of debt securities and the related gross realized capital gains and losses for the three months ended March 31, 2014 and 2013 were as follows:
	(Millions)	2014			2013
	Proceeds on sales	$	1,092.80		$	1,375.70
	Gross realized capital gains	24.6			37.3
	Gross realized capital losses	13			7.4
Activity in mortgage loan portfolio	'
	During the three months ended March 31, 2014 and 2013 we had the following activity in our mortgage loan portfolio:
	(Millions)	2014			2013
	New mortgage loans	$	33.9		$	42.5
	Mortgage loans fully repaid	19.8			16.9
Mortgage loan internal credit rating	'
	Based upon our most recent assessments at March 31, 2014 and December 31, 2013, our mortgage loans were given the following credit quality indicators:
	(In Millions, except credit ratings indicator)	March 31,			December 31,
		2014			2013
	1	$	68.3		$	69.2
	2 to 4	1,399.00			1,399.60
	5	30.2			30.6
	6 and 7	50.1			50.2
	Total	$	1,547.60		$	1,549.60
Net Investment Income	'
	Sources of net investment income for the three months ended March 31, 2014 and 2013 were as follows:
	(Millions)	2014			2013
	Debt securities	$	198.1		$	188.8
	Mortgage loans	23.9			24.8
	Other investments	30.1			29.6
	Gross investment income	252.1			243.2
	Less: investment expenses	(7.9		)	(8.1		)
	Net investment income (1)	$	244.2		$	235.1
	(1)	Net investment income includes $80.4 million and $79.3 million for the three months ended March 31, 2014 and 2013, respectively, related to investments supporting our experience-rated and discontinued products.

Other_Comprehensive_Loss_Incom1

Other Comprehensive (Loss) Income (Tables)	3 Months Ended
	Mar. 31, 2014
Other Comprehensive Income (Loss), Net of Tax [Abstract]	'
Schedule of Accumulated Other Comprehensive Income (Loss)	'
	Shareholders’ equity included the following activity in accumulated other comprehensive loss for the three months ended March 31, 2014 and 2013:
		Net Unrealized Gains (Losses)															Pension and OPEB Plans										Total
																											Accumulated
																											Other
		Securities										Foreign															Comprehensive
												Currency															(Loss) Income
												and
	(Millions)	Previously					All Other					Derivatives			Unrecognized					Unrecognized
		Impaired (1)													Net Actuarial					Prior Service
															Losses					Credit
	Three months ended March 31, 2014
	Balance at December 31, 2013	$	34.2				$	326.8				$	0.4				$	(1,293.8	)			$	20.3				$	(912.1	)
	Other comprehensive income (loss)
	before reclassifications	1.1					137.2					(12.5		)			—					—					125.8
	Amounts reclassified from accumulated
	other comprehensive income	(.4		)	(2	)	3.3			(2	)	(10.1		)	(3	)	7.7			(4	)	(.6		)	(4	)	(.1		)
	Other comprehensive income (loss)	0.7					140.5					(22.6		)			7.7					(.6		)			125.7
	Balance at March 31, 2014	$	34.9				$	467.3				$	(22.2	)			$	(1,286.1	)			$	19.7				$	(786.4	)
	Three months ended March 31, 2013
	Balance at December 31, 2012	$	57.3				$	825.2				$	(29.5	)			$	(1,909.4	)			$	23				$	(1,033.4	)
	Other comprehensive (loss) income
	before reclassifications	(9.4		)			(78.5		)			6.7					—					—					(81.2		)
	Amounts reclassified from accumulated
	other comprehensive income	3.7			(2	)	(15.8		)	(2	)	0.8			(3	)	12.6			(4	)	(.6		)	(4	)	0.7
	Other comprehensive (loss) income	(5.7		)			(94.3		)			7.5					12.6					(.6		)			(80.5		)
	Balance at March 31, 2013	$	51.6				$	730.9				$	(22.0	)			$	(1,896.8	)			$	22.4				$	(1,113.9	)
	(1)	Represents unrealized gains on the non-credit related component of impaired debt securities that we do not intend to sell and subsequent changes in the fair value of any previously impaired security.
	(2)	Reclassifications out of accumulated other comprehensive income for previously impaired debt securities and all other securities are reflected in net realized capital gains (losses) within the Consolidated Statement of Income.
	(3)	Reclassifications out of accumulated other comprehensive income for foreign currency gains (losses) and derivatives are reflected in net realized capital gains (losses) within the Consolidated Statement of Income, except for the effective portion of derivatives related to interest rate swaps which are reflected in interest expense and were not material during the three months ended March 31, 2014 or 2013. Refer to Note 10 of Condensed Notes to Consolidated Financial Statements beginning on page 25 for additional information.
	(4)	Reclassifications out of accumulated other comprehensive income for pension and OPEB plan expenses are reflected in general and administrative expenses within the Consolidated Statement of Income. Refer to Note 9 of Condensed Notes to Consolidated Financial Statements beginning on page 24 for additional information.

Financial_Instruments_Tables

Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Fair Value of Financial Assets	'
	Financial assets and liabilities measured at fair value on a recurring basis in our balance sheets at March 31, 2014 and December 31, 2013 were as follows:
	(Millions)	Level 1			Level 2				Level 3				Total
	March 31, 2014
	Assets:
	Debt securities:
	U.S. government securities	$	1,169.30		$	232.8			$	—			$	1,402.10
	States, municipalities and political subdivisions	—			4,185.40				1.2				4,186.60
	U.S. corporate securities	—			8,199.30				42.9				8,242.20
	Foreign securities	—			3,456.90				28.3				3,485.20
	Residential mortgage-backed securities	—			963.1				—				963.1
	Commercial mortgage-backed securities	—			1,462.80				7.5				1,470.30
	Other asset-backed securities	—			306.3				37.4				343.7
	Redeemable preferred securities	—			62.4				4.1				66.5
	Total debt securities	1,169.30			18,869.00				121.4				20,159.70
	Equity securities	37.4			—				23.1				60.5
	Derivatives	—			0.4				—				0.4
	Total	$	1,206.70		$	18,869.40			$	144.5			$	20,220.60
	Liabilities:
	Derivatives	$	—		$	3.6			$	—			$	3.6
	December 31, 2013
	Assets:
	Debt securities:
	U.S. government securities	$	1,237.50		$	225			$	—			$	1,462.50
	States, municipalities and political subdivisions	—			4,161.00				1.3				4,162.30
	U.S. corporate securities	—			7,911.40				31.2				7,942.60
	Foreign securities	—			3,311.60				43.9				3,355.50
	Residential mortgage-backed securities	—			924.2				—				924.2
	Commercial mortgage-backed securities	—			1,399.50				7.5				1,407.00
	Other asset-backed securities	—			317.3				32.3				349.6
	Redeemable preferred securities	—			61.3				4.1				65.4
	Total debt securities	1,237.50			18,311.30				120.3				19,669.10
	Equity securities	17.1			—				44.2				61.3
	Derivatives	—			49.1				—				49.1
	Total	$	1,254.60		$	18,360.40			$	164.5			$	19,779.50
	Liabilities:
	Derivatives	$	—		$	1.9			$	—			$	1.9
Carrying Value and Estimated Fair Value of Certain Financial Instruments	'
	The carrying value and estimated fair value classified by level of fair value hierarchy for certain of our financial instruments at March 31, 2014 and December 31, 2013 were as follows:
		Carrying			Estimated Fair Value
	(Millions)	Value			Level 1			Level 2			Level 3			Total
	March 31, 2014
	Assets:
	Mortgage loans	$	1,547.60		$	—		$	—		$	1,595.20		$	1,595.20
	Bank loans	209.6			—			198.9			10.1			209
	Liabilities:
	Investment contract liabilities:
	With a fixed maturity	8.9			—			—			8.9			8.9
	Without a fixed maturity	557.1			—			—			545.1			545.1
	Long-term debt	8,238.60			—			8,792.20			—			8,792.20
	December 31, 2013
	Assets:
	Mortgage loans	$	1,549.60		$	—		$	—		$	1,584.80		$	1,584.80
	Bank loans	181.7			—			171.5			9.8			181.3
	Liabilities:
	Investment contract liabilities:
	With a fixed maturity	8.9			—			—			8.9			8.9
	Without a fixed maturity	572.3			—			—			553.2			553.2
	Long-term debt	8,252.60			—			8,670.60			—			8,670.60
Separate Account Financial Assets	'
	Separate Accounts financial assets at March 31, 2014 and December 31, 2013 were as follows:
		March 31, 2014														December 31, 2013
	(Millions)	Level 1			Level 2				Level 3				Total			Level 1		Level 2		Level 3		Total
	Debt securities	$	753.3		$	2,245.70			$	1			$	3,000.00		$	726.4	$	2,227.00	$	0.6	$	2,954.00
	Equity securities	189.5			4.5				—				194			188.4		3.3		—		191.7
	Derivatives	—			0.7				—				0.7			—		0.8		—		0.8
	Common/collective trusts	—			729.7				—				729.7			—		710.4		—		710.4
	Total (1)	$	942.8		$	2,980.60			$	1			$	3,924.40		$	914.8	$	2,941.50	$	0.6	$	3,856.90
	(1)	Excludes $255.3 million and $115.6 million of cash and cash equivalents and other receivables at March 31, 2014 and December 31, 2013, respectively.
Balance Sheet Offsetting Assets	'
	Financial assets, including derivative assets, subject to offsetting and enforceable master netting arrangements as of March 31, 2014 and December 31, 2013 were as follows:
		Gross Amounts of Recognized Assets (1)		Gross Amounts Not Offset
				in the Balance Sheets
				Financial Instruments			Cash Collateral Received
	(Millions)									Net Amount
	31-Mar-14
	Derivatives	$	0.4	$	11.3		$	(.2	)	$	11.5
	Total	$	0.4	$	11.3		$	(.2	)	$	11.5
	31-Dec-13
	Derivatives	$	49.1	$	13.3		$	(47.1	)	$	15.3
	Total	$	49.1	$	13.3		$	(47.1	)	$	15.3
	(1) There were no amounts offset in our balance sheets at March 31, 2014 or December 31, 2013.
Balance Sheet Offsetting Liabilities	'
	Financial liabilities, including derivative liabilities, subject to offsetting and enforceable master netting arrangements as of March 31, 2014 and December 31, 2013 were as follows:
		Gross Amounts of Recognized Liabilities (1)		Gross Amounts Not Offset
				in the Balance Sheets
				Financial Instruments			Cash Collateral Paid
	(Millions)									Net Amount
	31-Mar-14
	Derivatives	$	3.6	$	—		$	(4.9	)	$	(1.3	)
	Securities lending	720.8		(720.7		)	—			0.1
	Repurchase agreements	156.2		—			—			156.2
	Total	$	880.6	$	(720.7	)	$	(4.9	)	$	155
	31-Dec-13
	Derivatives	$	1.9	$	—		$	(.7	)	$	1.2
	Securities lending	792.6		(792.6		)	—			—
	Total	$	794.5	$	(792.6	)	$	(.7	)	$	1.2
	(1) There were no amounts offset in our balance sheets at March 31, 2014 or December 31, 2013.

Pension_and_Other_Postretireme1

Pension and Other Postretirement Plans (Tables)	3 Months Ended
	Mar. 31, 2014
Compensation and Retirement Disclosure [Abstract]	'
Components of net periodic benefit cost	'
	Components of the net periodic benefit (income) cost of our defined benefit pension plans and other postretirement employee benefit (“OPEB”) plans for the three months ended March 31, 2014 and 2013 were as follows:
		Pension Plans						OPEB Plans
	(Millions)	2014			2013			2014			2013
	Service cost	$	—		$	—		$	—		$	—
	Amortization of prior service credit	(.1		)	(.1		)	(.9		)	(.9		)
	Interest cost	72.1			67.9			3			2.8
	Expected return on plan assets	(105.6		)	(99.1		)	(.8		)	(.6		)
	Recognized net actuarial losses	11.7			18.9			0.2			0.5
	Net periodic benefit (income) cost	$	(21.9	)	$	(12.4	)	$	1.5		$	1.8

Debt_Tables

Debt (Tables)	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Carrying Value of Long-Term Debt	'
	The carrying value of our long-term debt at March 31, 2014 and December 31, 2013 was as follows:
	(Millions)	March 31,		December 31,
		2014		2013
	Senior notes, 6.3%, due 2014	$	382.4	$	387.3
	Senior notes, 6.125%, due 2015	237.8		240.6
	Senior notes, 6.0%, due 2016	—		748.9
	Senior notes, 5.95%, due 2017	430.2		434.2
	Senior notes, 1.75%, due 2017	249		248.9
	Senior notes, 1.5%, due 2017	498.3		498.2
	Senior notes, 6.5%, due 2018	495		494.9
	Senior notes, 2.2%, due 2019	374.6		—
	Senior notes, 3.95%, due 2020	744.5		744.3
	Senior notes, 5.45%, due 2021	698.9		702.3
	Senior notes, 4.125%, due 2021	495		494.8
	Senior notes, 2.75%, due 2022	985.5		985.1
	Senior notes, 6.625%, due 2036	769.8		769.8
	Senior notes, 6.75%, due 2037	530.6		530.6
	Senior notes, 4.5%, due 2042	480.2		480.1
	Senior notes, 4.125%, due 2042	492.7		492.6
	Senior notes, 4.75%, due 2044	374.1		—
	Total long-term debt	8,238.60		8,252.60
	Less current portion of long-term debt (1)	620.2		387.3
	Total long-term debt, less current portion	$	7,618.40	$	7,865.30
	-1	At March 31, 2014, our 6.125% senior notes due January 2015 and 6.3% senior notes due August 2014 are classified as current in the accompanying consolidated balance sheet.

Capital_Stock_Tables

Capital Stock (Tables)	3 Months Ended
	Mar. 31, 2014
Class of Stock Disclosures [Abstract]	'
Dividends declared	'
	During the three months ended March 31, 2014 our Board declared the following cash dividend:
	Date Declared	Dividend Amount			Stockholders of	Date Paid/	Total Dividends
		Per Share			Record Date	To be Paid	(Millions)
	February 28, 2014		$	0.225	April 10, 2014	April 25, 2014		$	80.5
Black Scholes option pricing model	'
	In 2014, we granted SARs with an estimated fair market value of $22.68 per unit. The fair value per unit was calculated on the grant date using a Black-Scholes option pricing model using the following assumptions:
	Expected term (in years)	5.72
	Expected volatility	35.8		%
	Risk-free interest rate	1.74		%
	Dividend yield	1.36		%
	Initial price	$	72.26

Segment_Information_Tables

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Summarized financial information of segments	'
	Summarized financial information of our segments for the three months ended March 31, 2014 and 2013 were as follows:
	(Millions)	Health			Group			Large Case		Corporate			Total Company
		Care			Insurance			Pensions		Financing
	Three Months Ended March 31, 2014
	Revenue from external customers	$	13,131.40		$	544.4		$	46.3	$	—		$	13,722.10
	Operating earnings (loss) (1)	719			41.2			4.8		(43.0		)	722
	Three Months Ended March 31, 2013
	Revenue from external customers	$	8,723.20		$	505.3		$	45	$	—		$	9,273.50
	Operating earnings (loss) (1)	513.2			31.9			6.2		(34.8		)	516.5
	(1)	Operating earnings (loss) excludes net realized capital gains or losses, amortization of other acquired intangible assets and the other items described in the reconciliation below.
Reconciliation of Operating Earnings to Net Income	'
	A reconciliation of operating earnings (1) to net income attributable to Aetna for the three months ended March 31, 2014 and 2013 was as follows:
	(Millions)	2014			2013
	Operating earnings (1)	$	722		$	516.5
	Transaction and integration-related costs, net of tax	(41.9		)	(24.6		)
	Loss on early extinguishment of long-term debt, net of tax	(59.7		)	—
	Release of litigation-related reserve, net of tax	67			—
	Amortization of other acquired intangible assets, net of tax	(40.4		)	(21.1		)
	Net realized capital gains, net of tax	18.5			19.3
	Net income attributable to Aetna	$	665.5		$	490.1
	(1)	In addition to net realized capital gains (losses) and amortization of other acquired intangible assets, the following other items are excluded from operating earnings because we believe they neither relate to the ordinary course of our business nor reflect our underlying business performance:
	•	We incurred transaction and integration-related costs of $41.9 million ($63.7 million pretax) and $24.6 million ($37.1 million pretax) during the three months ended March 31, 2014 and 2013, respectively, related to the acquisition of Coventry. Transaction costs include advisory, legal and other professional fees which are not deductible for tax purposes and are reflected in our GAAP Consolidated Statements of Income in general and administrative expenses. Transaction costs also include transaction-related payments as well as expenses related to the negative cost of carry associated with the permanent financing that we obtained in November 2012 for the Coventry acquisition. Prior to the Effective Date, the negative cost of carry was excluded from operating earnings. The components of the negative cost of carry are reflected in our GAAP Consolidated Statements of Income in interest expense, net investment income, and general and administrative expenses. On and after the Effective Date, the interest expense and general and administrative expenses associated with the permanent financing are no longer excluded from operating earnings.
	•	In the first quarter of 2014, we incurred a loss on the early extinguishment of long-term debt of $59.7 million ($91.9 million pretax) related to the redemption of our 6.0% senior notes due 2016.
	•	In the fourth quarter of 2012, we recorded a charge of $78.0 million ($120.0 million pretax) related to the settlement of purported class action litigation regarding our payment practices related to out-of-network health care providers. That charge included the estimated cost of legal fees of plaintiffs' counsel and the costs of administering the settlement. In the first quarter of 2014, we exercised our right to terminate the settlement agreement. As a result, we released the reserve established in connection with the settlement agreement, net of amounts due to the settlement administrator, which reduced first quarter 2014 other general and administrative expenses by $67.0 million ($103.0 million pretax). Refer to Note 13 beginning on page 27 for additional information on the termination of the settlement agreement.

Discontinued_Products_Tables

Discontinued Products (Tables)	3 Months Ended
	Mar. 31, 2014
Discontinued Products [Abstract]	'
Activity in the Reserve for Anticipated Future Losses	'
	The activity in the reserve for anticipated future losses on discontinued products for the three months ended March 31, 2014 and 2013 (pretax) was as follows:
	(Millions)	2014		2013
	Reserve, beginning of period	$	979.5	$	978.5
	Operating income	5.8		8.8
	Net realized capital gains	6.3		32.8
	Reserve, end of period	$	991.6	$	1,020.10
Assets and Liabilities Supporting Discontinued Products	'
	Assets and liabilities supporting discontinued products at March 31, 2014 and December 31, 2013 were as
	follows: (1)
	(Millions)	2014		2013
	Assets:
	Debt and equity securities available for sale	$	2,367.00	$	2,372.60
	Mortgage loans	420.9		407
	Other investments	685		663.9
	Total investments	3,472.90		3,443.50
	Other assets	86.6		85.2
	Collateral received under securities loan agreements	175		204.4
	Current and deferred income taxes	17.2		14.4
	Receivable from continuing products (2)	541.3		533.1
	Total assets	$	4,293.00	$	4,280.60
	Liabilities:
	Future policy benefits	$	2,765.30	$	2,804.80
	Reserve for anticipated future losses on discontinued products	991.6		979.5
	Collateral payable under securities loan agreements	175		204.4
	Other liabilities (3)	361.1		291.9
	Total liabilities	$	4,293.00	$	4,280.60
	(1)	Assets supporting the discontinued products are distinguished from assets supporting continuing products.
	(2)	At the time of discontinuance, a receivable from Large Case Pensions' continuing products was established on the discontinued products balance sheet. This receivable represented the net present value of anticipated cash shortfalls in the discontinued products, which will be funded from continuing products. Interest on the receivable is accrued at the discount rate that was used to calculate the reserve. The offsetting payable, on which interest is similarly accrued, is reflected in continuing products. Interest on the payable generally offsets investment income on the assets available to fund the shortfall. These amounts are eliminated in consolidation.
	(3)	Net unrealized capital gains on the available-for-sale debt securities are included in other liabilities and are not reflected in consolidated shareholders’ equity.

Organization_Details

Organization (Details) (USD $)	7-May-13
In Billions, unless otherwise specified
Organization [Line Items]	'
Total purchase price for an acquisition	$8.70

Acquisitions_Completed_Disposi2

Acquisitions, Completed Disposition (Details) (USD $)	12 Months Ended
Share data in Millions, unless otherwise specified	Dec. 31, 2013	7-May-13
Business Acquisition [Line Items]	'	'
Total purchase price for an acquisition	'	$8,700,000,000
Long-term debt acquired	1,800,000,000	'
Cash to be Received by Shareholders Upon Acquisition, per share	'	27.3
Exchange ratio used in calculation of merger consideration	'	0.3885
Total number of shares issued in a business acquisition	52.2	'
Total value of equity consideration transferred	'	3,100,000,000
Cash consideration transferred	$3,800,000,000	'

Acquisitions_Completed_Disposi3

Acquisitions; Completed Disposition Pro Forma Financials (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2013
Business Acquisition, Pro Forma Information [Abstract]	'
Pro Forma Revenue	$12,939.40
Pro Forma Net Income (Loss)	$638.60
Pro Forma Earnings Per Share, Basic	$1.69
Pro Forma Earnings Per Share, Diluted	$1.67

Earnings_Per_Common_Share_Deta

Earnings Per Common Share (Details) (USD $)	3 Months Ended				12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'		'		'
Total number of shares issued in a business acquisition	'		'		52.2
Net income	$665.50		$490.10		'
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]	'		'		'
Weighted average shares used to compute basic EPS (in shares)	361.6		327.6		'
Dilutive effect of outstanding stock-based compensation awards (in shares)	3.4		3.1		'
Weighted average shares used to compute diluted EPS (in shares)	365		330.7		'
Basic EPS (in dollars per share)	$1.84		$1.50		'
Diluted EPS (in dollars per share)	$1.82		$1.48		'
Stock Appreciation Rights (SARs) [Member]	'		'		'
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]	'		'		'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)	1.3	[1]	6.7	[1]	'
Market Stock Units [Member]	'		'		'
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]	'		'		'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)	0.4	[2]	0.4	[2]	'
Performance Stock Units [Member]	'		'		'
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]	'		'		'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)	0.7	[2]	0.8	[2]	'
Performance Stock Appreciation Rights [Member]	'		'		'
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]	'		'		'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)	0.2	[2]	0	[2]	'
[1]	SARs are excluded from the calculation of diluted EPS if the exercise price is greater than the average market price of Aetna common shares during the period (i.e., the awards are anti-dilutive).
[2]	PSUs, certain MSUs with performance conditions and PSARs are excluded from the calculation of diluted EPS if all necessary performance conditions have not been satisfied at the end of the reporting period.

Operating_Expenses_Details

Operating Expenses (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2012
Health Insurer Fee	$154.80		'		'
ACA Reinsurance Program	84.9		'		'
Transaction and integration-related costs, pretax	63.7		37.1		'
General and administrative transaction and integration-related costs	'		24.3		'
Selling expenses	402.8		297.2		'
General and administrative expenses:	'		'		'
Salaries and related benefits	1,110.70		802.5		'
Other general and administrative expenses	936.9	[1],[2],[3]	639.5	[1],[2],[3]	'
Total general and administrative expenses	2,047.60		1,442		'
Total operating expenses	2,450.40		1,739.20		'
Litigation Settlement, Expense	'		'		120
Release of litigation-related reserve, pre-tax	$103		'		'
[1]	The three months ended March 31, 2014 include estimated ACA mandated fees comprised primarily of the HIF and our contribution to the funding of the reinsurance program of $154.8 million and $84.9 million, respectively. Refer to Note 2 beginning on page 6 for additional information on ACA mandated fees.
[2]	In the fourth quarter of 2012, we recorded a charge of $120.0 million pretax related to the settlement of purported class action litigation regarding Aetna's payment practices related to out-of-network health care providers. That charge included the estimated cost of legal fees of plaintiffs' counsel and the costs of administering the settlement. In the first quarter of 2014, we exercised our right to terminate the settlement agreement. As a result, we released the reserve established in connection with the settlement agreement, net of amounts due to the settlement administrator, which reduced first quarter 2014 other general and administrative expenses by $103.0 million pretax. Refer to Note 13 beginning on page 27 for additional information on the termination of the settlement agreement.
[3]	The three months ended March 31, 2014 include $63.7 million of integration-related costs related to the acquisition of Coventry. The three months ended March 31, 2013 include $24.3 million of transaction and integration-related costs related to the acquisition of Coventry, including advisory, legal and other professional services fees and transaction-related payments.

Investments_Details

Investments (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Total Investments [Line Items]	'	'
Current	$2,209.80	$2,063.80
Long-term investments	21,290.40	20,935
Total investments	23,500.20	22,998.80
Debt And Equity Securities Available For Sale [Member]	'	'
Total Investments [Line Items]	'	'
Current	2,121	1,977.40
Long-term investments	18,099.20	17,753
Total investments	20,220.20	19,730.40
Mortgage Loans [Member]	'	'
Total Investments [Line Items]	'	'
Current	83.1	84.9
Long-term investments	1,464.50	1,464.70
Total investments	1,547.60	1,549.60
Other Investments [Member]	'	'
Total Investments [Line Items]	'	'
Current	5.7	1.5
Long-term investments	1,726.70	1,717.30
Total investments	1,732.40	1,718.80
Repurchase Agreements [Member]	'	'
Total Investments [Line Items]	'	'
Collateral under repurchase agreement	156	0
Securities loaned agreements [Member]	'	'
Total Investments [Line Items]	'	'
Securities Loaned, Asset	$696	$766

Investments_Debt_and_Equity_Se

Investments - Debt and Equity Securities (Details) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'		'
Non-credit related impairments previously recognized in other comprehensive income	$18.60		$22.80
Available-for-sale Securities, Amortized Cost Basis	19,149.60	[1]	18,974.50	[1]
Available-for-sale Securities, Gross Unrealized Gains	1,216.60	[1]	1,036.40	[1]
Available-for-sale Securities, Gross Unrealized Losses	-146	[1]	-280.5	[1]
Available-for-sale Securities, Fair Value Disclosure	20,220.20	[1]	19,730.40	[1]
Net Unrealized Capital (Loss) Gains	5.4		6.6
Supporting Discontinued And Experience Rated Products [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Gross Unrealized Gains	348.8		291.3
Available-for-sale Securities, Gross Unrealized Losses	-28.6		-60.3
Available-for-sale Securities, Fair Value Disclosure	3,700		3,700
Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Amortized Cost Basis	19,103.80		18,936
Available-for-sale Securities, Gross Unrealized Gains	1,197.20		1,009.90
Available-for-sale Securities, Gross Unrealized Losses	-141.3		-276.8
Available-for-sale Securities, Fair Value Disclosure	20,159.70		19,669.10
US Government Agencies Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Amortized Cost Basis	1,325.40		1,396.80
Available-for-sale Securities, Gross Unrealized Gains	77.8		68.7
Available-for-sale Securities, Gross Unrealized Losses	-1.1		-3
Available-for-sale Securities, Fair Value Disclosure	1,402.10		1,462.50
US States and Political Subdivisions Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Amortized Cost Basis	4,043.10		4,118.50
Available-for-sale Securities, Gross Unrealized Gains	182.9		126.6
Available-for-sale Securities, Gross Unrealized Losses	-39.4		-82.8
Available-for-sale Securities, Fair Value Disclosure	4,186.60		4,162.30
Domestic Corporate Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Amortized Cost Basis	7,725.40		7,559
Available-for-sale Securities, Gross Unrealized Gains	572.3		493.7
Available-for-sale Securities, Gross Unrealized Losses	-55.5		-110.1
Available-for-sale Securities, Fair Value Disclosure	8,242.20		7,942.60
Foreign Corporate Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Amortized Cost Basis	3,267		3,209.60
Available-for-sale Securities, Gross Unrealized Gains	244.3		198.9
Available-for-sale Securities, Gross Unrealized Losses	-26.1		-53
Available-for-sale Securities, Fair Value Disclosure	3,485.20		3,355.50
Residential Mortgage Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Amortized Cost Basis	960		928.4
Available-for-sale Securities, Gross Unrealized Gains	18		16.9
Available-for-sale Securities, Gross Unrealized Losses	-14.9		-21.1
Available-for-sale Securities, Fair Value Disclosure	963.1		924.2
Commercial Mortgage Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Amortized Cost Basis	1,389.40		1,323.50
Available-for-sale Securities, Gross Unrealized Gains	84		88.2
Available-for-sale Securities, Gross Unrealized Losses	-3.1	[2]	-4.7	[2]
Available-for-sale Securities, Fair Value Disclosure	1,470.30		1,407
Other Asset-Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Amortized Cost Basis	336.7		343.4
Available-for-sale Securities, Gross Unrealized Gains	8.2		8.3
Available-for-sale Securities, Gross Unrealized Losses	-1.2	[2]	-2.1	[2]
Available-for-sale Securities, Fair Value Disclosure	343.7		349.6
Redeemable Preferred Stock [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Amortized Cost Basis	56.8		56.8
Available-for-sale Securities, Gross Unrealized Gains	9.7		8.6
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Fair Value Disclosure	66.5		65.4
Equity Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Amortized Cost Basis	45.8		38.5
Available-for-sale Securities, Gross Unrealized Gains	19.4		26.5
Available-for-sale Securities, Gross Unrealized Losses	-4.7		-3.7
Available-for-sale Securities, Fair Value Disclosure	$60.50		$61.30
[1]	Investment risks associated with our experience-rated and discontinued products generally do not impact our operating results (refer to Note 16 beginning on page 32 for additional information on our accounting for discontinued products). At March 31, 2014, debt and equity securities with a fair value of approximately $3.7 billion, gross unrealized capital gains of $348.8 million and gross unrealized capital losses of $28.6 million and, at December 31, 2013, debt and equity securities with a fair value of approximately $3.7 billion, gross unrealized capital gains of $291.3 million and gross unrealized capital losses of $60.3 million were included in total debt and equity securities, but support our experience-rated and discontinued products. Changes in net unrealized capital gains (losses) on these securities are not reflected in accumulated other comprehensive income.
[2]	At March 31, 2014 and December 31, 2013, we held securities for which we previously recognized $18.6 million and $22.8 million, respectively, of non-credit related impairments in accumulated other comprehensive loss. These securities had a net unrealized capital gain at March 31, 2014 and December 31, 2013 of $5.4 million and $6.6 million, respectively.

Investments_Debt_Securities_by

Investments - Debt Securities by Maturity (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Available-for-sale Securities, Debt Maturities [Abstract]	'		'
Available-for-sale Securities, Fair Value Disclosure	$20,220.20	[1]	$19,730.40	[1]
Debt Securities [Member]	'		'
Available-for-sale Securities, Debt Maturities [Abstract]	'		'
Available-for-sale Securities, Fair Value Disclosure	20,159.70		19,669.10
Available-for-sale Securities With Established Maturities [Member]	'		'
Available-for-sale Securities, Debt Maturities [Abstract]	'		'
Due To Mature Less Than One Year	949.1		'
Due to mature one year through five years	5,424.20		'
Due to mature after five years through ten years	5,721		'
Due to mature greater than ten years	5,288.30		'
Residential Mortgage Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available For Sale Securities, Weighted Average Duration Of Securities	'4 years 10 months 10 days		'
Available-for-sale Securities, Debt Maturities [Abstract]	'		'
Available-for-sale Securities, Fair Value Disclosure	963.1		924.2
Commercial Mortgage Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available For Sale Securities, Weighted Average Duration Of Securities	'2 years 5 months 16 days		'
Available-for-sale Securities, Debt Maturities [Abstract]	'		'
Available-for-sale Securities, Fair Value Disclosure	1,470.30		1,407
Other Asset-Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available For Sale Securities, Weighted Average Duration Of Securities	'2 years 9 months 4 days		'
Available-for-sale Securities, Debt Maturities [Abstract]	'		'
Available-for-sale Securities, Fair Value Disclosure	$343.70		$349.60
[1]	Investment risks associated with our experience-rated and discontinued products generally do not impact our operating results (refer to Note 16 beginning on page 32 for additional information on our accounting for discontinued products). At March 31, 2014, debt and equity securities with a fair value of approximately $3.7 billion, gross unrealized capital gains of $348.8 million and gross unrealized capital losses of $28.6 million and, at December 31, 2013, debt and equity securities with a fair value of approximately $3.7 billion, gross unrealized capital gains of $291.3 million and gross unrealized capital losses of $60.3 million were included in total debt and equity securities, but support our experience-rated and discontinued products. Changes in net unrealized capital gains (losses) on these securities are not reflected in accumulated other comprehensive income.

Investments_Unrealized_Loss_Po

Investments - Unrealized Loss Position (Details) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$4,038.40	[1]	$6,203.50	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	106	[1]	230.7	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	528.8	[1]	490.6	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	40	[1]	49.8	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4,567.20	[1]	6,694.10	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	146	[1]	280.5	[1]
Supporting Discontinued And Experience Rated Products [Member]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	598		1,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	28.6		60.3
Debt Securities [Member]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	4,038.40		6,203.50
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	106		230.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	513.8		474.4
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	35.3		46.1
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4,552.20	[1]	6,677.90	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	141.3	[1]	276.8	[1]
Debt Securities [Member] | Supporting Discontinued And Experience Rated Products [Member]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	583		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	23.9		'
Debt Securities [Member] | Supporting Remaining Products [Member]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	3,969.20		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	117.4		'
US Government Agencies Debt Securities [Member]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	51.4		555.9
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0.8		2.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	13.4		13.4
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0.3		0.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	64.8	[1]	569.3	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1.1	[1]	3	[1]
US States and Political Subdivisions Debt Securities [Member]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,136.10		1,779.90
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	31.5		73.1
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	155.7		132.4
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	7.9		9.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,291.80	[1]	1,912.30	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	39.4	[1]	82.8	[1]
Domestic Corporate Debt Securities [Member]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,558.40		2,196.80
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	39.3		88
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	181.9		170
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	16.2		22.1
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,740.30	[1]	2,366.80	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	55.5	[1]	110.1	[1]
Foreign Corporate Debt Securities [Member]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	569.3		875.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	18.9		43.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	100.9		90.9
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	7.2		9.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	670.2	[1]	966.1	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	26.1	[1]	53	[1]
Residential Mortgage Backed Securities [Member]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	462.5		541.1
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	11.7		17.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	35		35
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	3.2		3.8
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	497.5	[1]	576.1	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	14.9	[1]	21.1	[1]
Commercial Mortgage Backed Securities [Member]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	183.2		162.4
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	2.7		4.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	24.9		25
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0.4		0.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	208.1	[1]	187.4	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	3.1	[1]	4.7	[1]
Other Asset-Backed Securities [Member]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	73.1		87.8
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	1.1		1.9
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	2		7.7
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0.1		0.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	75.1	[1]	95.5	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1.2	[1]	2.1	[1]
Redeemable Preferred Stock [Member]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	4.4		4.4
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4.4	[1]	4.4	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0	[1]	0	[1]
Equity Securities [Member]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	15		16.2
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	4.7		3.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	15	[1]	16.2	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	$4.70	[1]	$3.70	[1]
[1]	At March 31, 2014 and December 31, 2013, debt and equity securities in an unrealized capital loss position of $28.6 million and $60.3 million, respectively, and with related fair value of $598.0 million and $1.0 billion, respectively, related to experience-rated and discontinued products.

Investments_Unrealized_Loss_Po1

Investments - Unrealized Loss Position Maturities (Details) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	$146	[1]	$280.50	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4,567.20	[1]	6,694.10	[1]
Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	141.3	[1]	276.8	[1]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4,552.20	[1]	6,677.90	[1]
Supporting Remaining Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	117.4		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	3,969.20		'
Supporting Discontinued And Experience Rated Products [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	28.6		60.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	598		1,000
Supporting Discontinued And Experience Rated Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	23.9		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	583		'
Maturing in Less than one Year [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0.8		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	38.9		'
Maturing in Less than one Year [Member] | Supporting Remaining Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0.8		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	38.9		'
Maturing in Less than one Year [Member] | Supporting Discontinued And Experience Rated Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	0		'
Maturing in One Through Five Years [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	8.4		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	907.7		'
Maturing in One Through Five Years [Member] | Supporting Remaining Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	8.1		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	882.1		'
Maturing in One Through Five Years [Member] | Supporting Discontinued And Experience Rated Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0.3		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	25.6		'
Maturing After Five Years Through Ten Years [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	51		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,701.70		'
Maturing After Five Years Through Ten Years [Member] | Supporting Remaining Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	43.3		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,457.40		'
Maturing After Five Years Through Ten Years [Member] | Supporting Discontinued And Experience Rated Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	7.7		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	244.3		'
Maturing in Greater Than Ten Years [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	61.9		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,123.20		'
Maturing in Greater Than Ten Years [Member] | Supporting Remaining Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	46.6		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	837.7		'
Maturing in Greater Than Ten Years [Member] | Supporting Discontinued And Experience Rated Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	15.3		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	285.5		'
Residential Mortgage Backed Securities [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	14.9		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	497.5		'
Residential Mortgage Backed Securities [Member] | Supporting Remaining Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	14.7		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	486.7		'
Residential Mortgage Backed Securities [Member] | Supporting Discontinued And Experience Rated Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0.2		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	10.8		'
Commercial Mortgage Backed Securities [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	3.1		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	208.1		'
Commercial Mortgage Backed Securities [Member] | Supporting Remaining Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	2.8		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	199.2		'
Commercial Mortgage Backed Securities [Member] | Supporting Discontinued And Experience Rated Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0.3		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	8.9		'
Other Asset-Backed Securities [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1.2		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	75.1		'
Other Asset-Backed Securities [Member] | Supporting Remaining Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1.1		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	67.2		'
Other Asset-Backed Securities [Member] | Supporting Discontinued And Experience Rated Products [Member] | Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0.1		'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$7.90		'
[1]	At March 31, 2014 and December 31, 2013, debt and equity securities in an unrealized capital loss position of $28.6 million and $60.3 million, respectively, and with related fair value of $598.0 million and $1.0 billion, respectively, related to experience-rated and discontinued products.

Investments_Realized_Gains_Det

Investments - Realized Gains (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]	'	'
OTTI losses on securities	($0.20)	($5.80)
Portion of OTTI losses recognized in other comprehensive income	0	0
Net OTTI losses on securities recognized in earnings	-0.2	-5.8
Net realized capital gains losses excluding OTTI losses on securities	28.7	36.1
Net realized capital (losses) gains	28.5	30.3
Debt Securities [Member]	'	'
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]	'	'
Proceeds On Sales	1,092.80	1,375.70
Gross Realized Capital Gains	24.6	37.3
Gross Realized Capital Losses	$13	$7.40

Investments_Mortgage_Loans_Det

Investments - Mortgage Loans (Details) (Commercial Real Estate [Member], USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Movement in Mortgage Loans on Real Estate [Roll Forward]	'	'	'
New Mortgage Loans	$33.90	$42.50	'
Mortgage loans fully repaid	19.8	16.9	'
Mortgage Loans on Real Estate	1,547.60	'	1,549.60
Category 1 [Member]	'	'	'
Movement in Mortgage Loans on Real Estate [Roll Forward]	'	'	'
Mortgage Loans on Real Estate	68.3	'	69.2
Category 2 to 4 [Member]	'	'	'
Movement in Mortgage Loans on Real Estate [Roll Forward]	'	'	'
Mortgage Loans on Real Estate	1,399	'	1,399.60
Category 5 [Member]	'	'	'
Movement in Mortgage Loans on Real Estate [Roll Forward]	'	'	'
Mortgage Loans on Real Estate	30.2	'	30.6
Categories 6 and 7 [Member]	'	'	'
Movement in Mortgage Loans on Real Estate [Roll Forward]	'	'	'
Mortgage Loans on Real Estate	$50.10	'	$50.20

Investments_Variable_Interest_

Investments - Variable Interest Entities and Noncontrolling Interests (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]	'	'	'	'
Long-term investments	$21,290,400,000	'	$20,935,000,000	'
Stockholders' Equity Attributable to Noncontrolling Interest	57,400,000	'	52,700,000	'
Noncontrolling Interest [Abstract]	'	'	'	'
Net Income Attributable to Non-controlling Interest	3,900,000	800,000	'	'
Variable Interest Entity, Not Primary Beneficiary [Member]	'	'	'	'
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]	'	'	'	'
Long-term investments	208,000,000	'	205,000,000	'
Real Estate Partnerships [Member]	'	'	'	'
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]	'	'	'	'
Variable Interest Entity Assets	5,400,000,000	'	5,800,000,000	'
Hedge Fund Partnerships [Member]	'	'	'	'
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]	'	'	'	'
Variable Interest Entity Assets	7,500,000,000	'	7,000,000,000	'
Noncontrolling Interest [Member]	'	'	'	'
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]	'	'	'	'
Stockholders' Equity Attributable to Noncontrolling Interest	57,400,000	45,900,000	52,700,000	23,400,000
Noncontrolling Interest [Abstract]	'	'	'	'
Net Income Attributable to Non-controlling Interest	$3,900,000	$800,000	'	'

Investments_Investment_Income_

Investments - Investment Income (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Schedule of Investment Income, Reported Amounts, by Category [Line Items]	'		'
Gross investment income	$252.10		$243.20
Less: investment expenses	-7.9		-8.1
Net Investment Income	244.2	[1]	235.1	[1]
Supporting Discontinued And Experience Rated Products [Member]	'		'
Schedule of Investment Income, Reported Amounts, by Category [Line Items]	'		'
Net Investment Income	80.4		79.3
Debt Securities [Member]	'		'
Schedule of Investment Income, Reported Amounts, by Category [Line Items]	'		'
Gross investment income	198.1		188.8
Mortgage Loans [Member]	'		'
Schedule of Investment Income, Reported Amounts, by Category [Line Items]	'		'
Gross investment income	23.9		24.8
Other Investments [Member]	'		'
Schedule of Investment Income, Reported Amounts, by Category [Line Items]	'		'
Gross investment income	$30.10		$29.60
[1]	Net investment income includes $80.4 million and $79.3 million for the three months ended March 31, 2014 and 2013, respectively, related to investments supporting our experience-rated and discontinued products.

Other_Comprehensive_Loss_Incom2

Other Comprehensive (Loss) Income (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'
Balance at beginning of period	($912.10)		'
Other comprehensive (loss) income	125.7		-80.5
Balance at end of period	-786.4		'
Net Unrealized Gains (Losses) Previously Impaired Securities [Member]	'		'
Comprehensive Income Loss [Line Items]	'		'
Net unrealized gains (losses)	1.1	[1]	-9.4	[1]
Net unrealized gains (losses) on securities, reclassification of gains to earnings	-0.4	[1],[2]	3.7	[1],[2]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'
Balance at beginning of period	34.2	[1]	57.3	[1]
Other comprehensive (loss) income	0.7	[1]	-5.7
Balance at end of period	34.9	[1]	51.6	[1]
Net Unrealized Gains (Losses) All Other Securities [Member]	'		'
Comprehensive Income Loss [Line Items]	'		'
Net unrealized gains (losses)	137.2		-78.5
Net unrealized gains (losses) on securities, reclassification of gains to earnings	3.3	[2]	-15.8	[2]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'
Balance at beginning of period	326.8		825.2
Other comprehensive (loss) income	140.5		-94.3
Balance at end of period	467.3		730.9
Net Unrealized Gains (Losses) Foreign Currency And Derivatives [Member]	'		'
Comprehensive Income Loss [Line Items]	'		'
Net unrealized gains (losses)	-12.5		6.7
Foreign currency and derivatives reclassification of losses to earnings	-10.1	[3]	0.8	[3]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'
Balance at beginning of period	0.4		-29.5
Other comprehensive (loss) income	-22.6		7.5
Balance at end of period	-22.2		-22
Pension And OPEB Plans Unrecognized Net Actuarial (Losses) [Member]	'		'
Comprehensive Income Loss [Line Items]	'		'
Other comprehensive income, Pensions and Other Post Retirement Employee Benefit Plans, net of tax	0		0
Amortization of net actuarial losses	7.7	[4]	12.6	[4]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'
Balance at beginning of period	-1,293.80		-1,909.40
Other comprehensive (loss) income	7.7		12.6
Balance at end of period	-1,286.10		-1,896.80
Pension And OPEB Plans Unrecognized Prior Service Cost [Member]	'		'
Comprehensive Income Loss [Line Items]	'		'
Other comprehensive income, Pensions and Other Post Retirement Employee Benefit Plans, net of tax	0		0
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Pension Cost, Net of Tax	-0.6	[4]	-0.6	[4]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'
Balance at beginning of period	20.3		23
Other comprehensive (loss) income	-0.6		-0.6
Balance at end of period	19.7		22.4
Accumulated Other Comprehensive Loss [Member]	'		'
Comprehensive Income Loss [Line Items]	'		'
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	125.8		-81.2
Other Comprehensive Income Loss Net Of Tax Reclassification To Earnings	-0.1		0.7
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'
Balance at beginning of period	-912.1		-1,033.40
Other comprehensive (loss) income	125.7		-80.5
Balance at end of period	($786.40)		($1,113.90)
[1]	Represents unrealized gains on the non-credit related component of impaired debt securities that we do not intend to sell and subsequent changes in the fair value of any previously impaired security.
[2]	Reclassifications out of accumulated other comprehensive income for previously impaired debt securities and all other securities are reflected in net realized capital gains (losses) within the Consolidated Statement of Income.
[3]	Reclassifications out of accumulated other comprehensive income for foreign currency gains (losses) and derivatives are reflected in net realized capital gains (losses) within the Consolidated Statement of Income, except for the effective portion of derivatives related to interest rate swaps which are reflected in interest expense and were not material during the three months ended March 31, 2014 or 2013. Refer to Note 10 of Condensed Notes to Consolidated Financial Statements beginning on page 25 for additional information.
[4]	Reclassifications out of accumulated other comprehensive income for pension and OPEB plan expenses are reflected in general and administrative expenses within the Consolidated Statement of Income. Refer to Note 9 of Condensed Notes to Consolidated Financial Statements beginning on page 24 for additional information.

Financial_Instruments_Fair_Val

Financial Instruments - Fair Value Measurements (Details) (USD $)	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013	Dec. 31, 2013
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	$20,220,200,000	[1]	'	$19,730,400,000	[1]
Gross transfers into Level 3	0		0	'
Transfers between Level 1 and 2, Separate Accounts	0		0	'
Gross transfers out of level 3	9,700,000		8,000,000	'
Gross transfers into Level 3, Separate Accounts	0		0	'
Gross transfers out of separate accounts	0		400,000	'
Debt Securities [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	20,159,700,000		'	19,669,100,000
US Government Agencies Debt Securities [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	1,402,100,000		'	1,462,500,000
US States and Political Subdivisions Debt Securities [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	4,186,600,000		'	4,162,300,000
Domestic Corporate Debt Securities [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	8,242,200,000		'	7,942,600,000
Foreign Corporate Debt Securities [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	3,485,200,000		'	3,355,500,000
Residential Mortgage Backed Securities [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	963,100,000		'	924,200,000
Commercial Mortgage Backed Securities [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	1,470,300,000		'	1,407,000,000
Other Asset-Backed Securities [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	343,700,000		'	349,600,000
Redeemable Preferred Stock [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	66,500,000		'	65,400,000
Equity Securities [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	60,500,000		'	61,300,000
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]	'		'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'	'
Derivative Liabilities	0		'	0
Assets, Fair Value Disclosure [Abstract]	'		'	'
Derivative Assets	0		'	0
Assets, Fair Value Disclosure	1,206,700,000		'	1,254,600,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]	'		'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'	'
Derivative Liabilities	3,600,000		'	1,900,000
Assets, Fair Value Disclosure [Abstract]	'		'	'
Derivative Assets	400,000		'	49,100,000
Assets, Fair Value Disclosure	18,869,400,000		'	18,360,400,000
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]	'		'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'	'
Derivative Liabilities	0		'	0
Assets, Fair Value Disclosure [Abstract]	'		'	'
Derivative Assets	0		'	0
Assets, Fair Value Disclosure	144,500,000		'	164,500,000
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'	'
Transfers between Level 1 and Level 2	0		0	'
Derivative Liabilities	3,600,000		'	1,900,000
Assets, Fair Value Disclosure [Abstract]	'		'	'
Derivative Assets	400,000		'	49,100,000
Assets, Fair Value Disclosure	20,220,600,000		'	19,779,500,000
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | Level 1 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	1,169,300,000		'	1,237,500,000
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | Level 2 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	18,869,000,000		'	18,311,300,000
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | Level 3 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	121,400,000		'	120,300,000
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	20,159,700,000		'	19,669,100,000
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Level 1 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	1,169,300,000		'	1,237,500,000
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Level 2 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	232,800,000		'	225,000,000
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Level 3 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	0		'	0
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	1,402,100,000		'	1,462,500,000
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Level 1 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	0		'	0
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Level 2 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	4,185,400,000		'	4,161,000,000
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Level 3 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	1,200,000		'	1,300,000
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	4,186,600,000		'	4,162,300,000
Fair Value, Measurements, Recurring [Member] | Domestic Corporate Debt Securities [Member] | Level 1 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	0		'	0
Fair Value, Measurements, Recurring [Member] | Domestic Corporate Debt Securities [Member] | Level 2 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	8,199,300,000		'	7,911,400,000
Fair Value, Measurements, Recurring [Member] | Domestic Corporate Debt Securities [Member] | Level 3 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	42,900,000		'	31,200,000
Fair Value, Measurements, Recurring [Member] | Domestic Corporate Debt Securities [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	8,242,200,000		'	7,942,600,000
Fair Value, Measurements, Recurring [Member] | Foreign Corporate Debt Securities [Member] | Level 1 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	0		'	0
Fair Value, Measurements, Recurring [Member] | Foreign Corporate Debt Securities [Member] | Level 2 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	3,456,900,000		'	3,311,600,000
Fair Value, Measurements, Recurring [Member] | Foreign Corporate Debt Securities [Member] | Level 3 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	28,300,000		'	43,900,000
Fair Value, Measurements, Recurring [Member] | Foreign Corporate Debt Securities [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	3,485,200,000		'	3,355,500,000
Fair Value, Measurements, Recurring [Member] | Residential Mortgage Backed Securities [Member] | Level 1 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	0		'	0
Fair Value, Measurements, Recurring [Member] | Residential Mortgage Backed Securities [Member] | Level 2 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	963,100,000		'	924,200,000
Fair Value, Measurements, Recurring [Member] | Residential Mortgage Backed Securities [Member] | Level 3 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	0		'	0
Fair Value, Measurements, Recurring [Member] | Residential Mortgage Backed Securities [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	963,100,000		'	924,200,000
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities [Member] | Level 1 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	0		'	0
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities [Member] | Level 2 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	1,462,800,000		'	1,399,500,000
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities [Member] | Level 3 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	7,500,000		'	7,500,000
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	1,470,300,000		'	1,407,000,000
Fair Value, Measurements, Recurring [Member] | Other Asset-Backed Securities [Member] | Level 1 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	0		'	0
Fair Value, Measurements, Recurring [Member] | Other Asset-Backed Securities [Member] | Level 2 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	306,300,000		'	317,300,000
Fair Value, Measurements, Recurring [Member] | Other Asset-Backed Securities [Member] | Level 3 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	37,400,000		'	32,300,000
Fair Value, Measurements, Recurring [Member] | Other Asset-Backed Securities [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	343,700,000		'	349,600,000
Fair Value, Measurements, Recurring [Member] | Redeemable Preferred Stock [Member] | Level 1 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	0		'	0
Fair Value, Measurements, Recurring [Member] | Redeemable Preferred Stock [Member] | Level 2 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	62,400,000		'	61,300,000
Fair Value, Measurements, Recurring [Member] | Redeemable Preferred Stock [Member] | Level 3 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	4,100,000		'	4,100,000
Fair Value, Measurements, Recurring [Member] | Redeemable Preferred Stock [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	66,500,000		'	65,400,000
Fair Value, Measurements, Recurring [Member] | Brokered Securities [Member] | Level 3 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	101,000,000		'	103,000,000
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member] | Level 1 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	37,400,000		'	17,100,000
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member] | Level 2 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	0		'	0
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member] | Level 3 [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	23,100,000		'	44,200,000
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Assets, Fair Value Disclosure [Abstract]	'		'	'
Available-for-sale Securities, Fair Value Disclosure	60,500,000		'	61,300,000
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]	'		'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'	'
Mortgage loans	0		'	0
Bank loans	0		'	0
Investment contracts with a fixed maturity	0		'	0
Investment contracts without a fixed maturity	0		'	0
Long-term debt	0		'	0
Fair Value, Measurements, Nonrecurring [Member] | Level 2 [Member]	'		'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'	'
Mortgage loans	0		'	0
Bank loans	198,900,000		'	171,500,000
Investment contracts with a fixed maturity	0		'	0
Investment contracts without a fixed maturity	0		'	0
Long-term debt	8,792,200,000		'	8,670,600,000
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member]	'		'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'	'
Mortgage loans	1,595,200,000		'	1,584,800,000
Bank loans	10,100,000		'	9,800,000
Investment contracts with a fixed maturity	8,900,000		'	8,900,000
Investment contracts without a fixed maturity	545,100,000		'	553,200,000
Long-term debt	0		'	0
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Nonrecurring [Member]	'		'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'	'
Mortgage loans	1,595,200,000		'	1,584,800,000
Bank loans	209,000,000		'	181,300,000
Investment contracts with a fixed maturity	8,900,000		'	8,900,000
Investment contracts without a fixed maturity	545,100,000		'	553,200,000
Long-term debt	8,792,200,000		'	8,670,600,000
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Measurements, Nonrecurring [Member]	'		'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'	'
Mortgage loans	1,547,600,000		'	1,549,600,000
Bank loans	209,600,000		'	181,700,000
Investment contracts with a fixed maturity	8,900,000		'	8,900,000
Investment contracts without a fixed maturity	557,100,000		'	572,300,000
Long-term debt	$8,238,600,000		'	$8,252,600,000
[1]	Investment risks associated with our experience-rated and discontinued products generally do not impact our operating results (refer to Note 16 beginning on page 32 for additional information on our accounting for discontinued products). At March 31, 2014, debt and equity securities with a fair value of approximately $3.7 billion, gross unrealized capital gains of $348.8 million and gross unrealized capital losses of $28.6 million and, at December 31, 2013, debt and equity securities with a fair value of approximately $3.7 billion, gross unrealized capital gains of $291.3 million and gross unrealized capital losses of $60.3 million were included in total debt and equity securities, but support our experience-rated and discontinued products. Changes in net unrealized capital gains (losses) on these securities are not reflected in accumulated other comprehensive income.

Financial_Instruments_Separate

Financial Instruments - Separate Accounts Fair Value (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013	Dec. 31, 2013
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Gross transfers into Level 3, Separate Accounts	$0		$0	'
Separate Account Assets	4,179.70		'	3,972.50
Gross transfers out of separate accounts	0		0.4	'
Transfers between Level 1 and 2, Separate Accounts	0		0	'
Fair Value, Measurements, Recurring [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	3,924.40	[1]	'	3,856.90	[1]
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	942.8	[1]	'	914.8	[1]
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	2,980.60	[1]	'	2,941.50	[1]
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	1	[1]	'	0.6	[1]
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	753.3		'	726.4
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	2,245.70		'	2,227
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	1		'	0.6
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	3,000		'	2,954
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	189.5		'	188.4
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	4.5		'	3.3
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	0		'	0
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	194		'	191.7
Derivatives [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	0		'	0
Derivatives [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	0.7		'	0.8
Derivatives [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	0		'	0
Derivatives [Member] | Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	0.7		'	0.8
Common/Collective Trusts [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	0		'	0
Common/Collective Trusts [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	729.7		'	710.4
Common/Collective Trusts [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	0		'	0
Common/Collective Trusts [Member] | Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value Measurement [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	729.7		'	710.4
Cash and Cash Equivalents [Member]	'		'	'
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]	'		'	'
Separate Account Assets	$255.30		'	$115.60
[1]	Excludes $255.3 million and $115.6 million of cash and cash equivalents and other receivables at March 31, 2014 and December 31, 2013, respectively.

Financial_Instruments_Balance_

Financial Instruments - Balance Sheet Offsetting (Details) (USD $)	Mar. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Derivatives, Fair Value [Line Items]	'		'
Collateral received under securities loan agreements	$720.70		$792.60
Net amount subject to offsetting	155		1.2
Total Gross Liabilities Recognized Subject to Offsetting	880.6	[1]	794.5	[1]
Fair Value, Measurements, Recurring [Member]	'		'
Derivatives, Fair Value [Line Items]	'		'
Derivative Asset, Fair Value, Gross Asset	0.4	[1]	49.1	[1]
Derivative Assets	11.5		15.3
Financial Instruments [Member]	'		'
Derivatives, Fair Value [Line Items]	'		'
Collateral Already Posted, Aggregate Fair Value	11.3		13.3
Collateral Already Posted, Aggregate Fair Value	-720.7		-792.6
Cash [Member]	'		'
Derivatives, Fair Value [Line Items]	'		'
Cash collateral received	-0.2		-47.1
Collateral Already Posted, Aggregate Fair Value	-4.9		-0.7
Derivative [Member]	'		'
Derivatives, Fair Value [Line Items]	'		'
Derivative Liabilities	-1.3		1.2
Derivative Liability, Fair Value, Gross Liability	3.6	[1]	1.9	[1]
Derivative [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Derivatives, Fair Value [Line Items]	'		'
Derivative Asset, Fair Value, Gross Asset	0.4	[1]	49.1	[1]
Derivative Assets	11.5		15.3
Derivative [Member] | Financial Instruments [Member]	'		'
Derivatives, Fair Value [Line Items]	'		'
Collateral Already Posted, Aggregate Fair Value	11.3		13.3
Collateral Already Posted, Aggregate Fair Value	0		0
Derivative [Member] | Cash [Member]	'		'
Derivatives, Fair Value [Line Items]	'		'
Cash collateral received	-0.2		-47.1
Collateral Already Posted, Aggregate Fair Value	-4.9		-0.7
Securities loaned agreements [Member]	'		'
Derivatives, Fair Value [Line Items]	'		'
Collateral received under securities loan agreements	720.8	[1]	792.6	[1]
Securities loaned agreements, net amount	0.1		0
Securities loaned agreements [Member] | Financial Instruments [Member]	'		'
Derivatives, Fair Value [Line Items]	'		'
Collateral Payable Under Securities Loan Agreements	-720.7		-792.6
Securities loaned agreements [Member] | Cash [Member]	'		'
Derivatives, Fair Value [Line Items]	'		'
Collateral Already Posted, Aggregate Fair Value	0		0
Repurchase Agreements [Member]	'		'
Derivatives, Fair Value [Line Items]	'		'
Collateral received under securities loan agreements	0		'
Repurchase agreement liability, net	156.2		'
Collateral payable under repurchase agreements	156.2	[1]	'
Repurchase Agreements [Member] | Financial Instruments [Member]	'		'
Derivatives, Fair Value [Line Items]	'		'
Collateral received under repurchase agreements, financial instruments	$0		'
[1]	There were no amounts offset in our balance sheets at March 31, 2014 or December 31, 2013.

Pension_and_Other_Postretireme2

Pension and Other Postretirement Plans (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Pension Plans [Member]	'	'
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]	'	'
Service cost	$0	$0
Amortization of prior service cost	-0.1	-0.1
Interest cost	72.1	67.9
Expected Return on Plan Assets	-105.6	-99.1
Amortization of net actuarial losses	11.7	18.9
Net periodic benefit (income) cost	-21.9	-12.4
OPEB Plans [Member]	'	'
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]	'	'
Service cost	0	0
Amortization of prior service cost	-0.9	-0.9
Interest cost	3	2.8
Expected Return on Plan Assets	-0.8	-0.6
Amortization of net actuarial losses	0.2	0.5
Net periodic benefit (income) cost	$1.50	$1.80

Debt_Details

Debt (Details) (USD $)

3 Months Ended

3 Months Ended

3 Months Ended

In Millions, unless otherwise specified

Mar. 31, 2014

Mar. 31, 2013

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Apr. 30, 2014

Mar. 31, 2014

Senior Notes, 6.3%, due 2014 [Member]

Senior Notes, 6.3%, due 2014 [Member]

Senior Notes, 6.125%, Due 2015 [Member]

Senior Notes, 6.125%, Due 2015 [Member]

Senior Notes, 6.0%, Due 2016 [Member]

Senior Notes, 6.0%, Due 2016 [Member]

Senior Notes, 5.95%, Due 2017 [Member]

Senior Notes, 5.95%, Due 2017 [Member]

Senior Notes, 1.75%, Due 2017 [Member]

Senior Notes, 1.75%, Due 2017 [Member]

Senior Notes, 1.5%, Due 2017 [Member]

Senior Notes, 1.5%, Due 2017 [Member]

Senior Notes, 6.5%, Due 2018 [Member]

Senior Notes, 6.5%, Due 2018 [Member]

Senior Notes, 2.2%, Due 2019 [Member]

Senior Notes, 2.2%, Due 2019 [Member]

Senior Notes, 3.95%, Due 2020 [Member]

Senior Notes, 3.95%, Due 2020 [Member]

Senior Notes, 5.45%, Due 2021 [Member]

Senior Notes, 5.45%, Due 2021 [Member]

Senior Notes, 4.125%, Due 2021 [Member]

Senior Notes, 4.125%, Due 2021 [Member]

Senior Notes, 2.75%, Due 2022 [Member]

Senior Notes, 2.75%, Due 2022 [Member]

Senior Notes, 6.625%, Due 2036 [Member]

Senior Notes, 6.625%, Due 2036 [Member]

Senior Notes, 6.75%, Due 2037 [Member]

Senior Notes, 6.75%, Due 2037 [Member]

Senior Notes, 4.5%, Due 2042 [Member]

Senior Notes, 4.5%, Due 2042 [Member]

Senior Notes, 4.125%, Due 2042 [Member]

Senior Notes, 4.125%, Due 2042 [Member]

Senior Notes, 4.75%, Due 2044 [Member]

Senior Notes, 4.75%, Due 2044 [Member]

Debt refinance [Domain]

Cash Flow Hedging [Member]

Cash Flow Hedging [Member]

Derivatives_and_swaps

Debt refinance [Domain]

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Loss on early extinguishment of debt

$91.90

$0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Proceeds from Issuance of Long-term Debt

741.9

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

375

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

375

'

'

'

'

Derivative, Notional Amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

375

250

500

Interest Rate Cash Flow Hedge Liability at Fair Value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2.9

Derivative, Cash Received on Hedge

34.2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Gain on Cash Flow Hedge Ineffectiveness

12

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net

22

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term Debt

8,238.60

'

8,252.60

'

'

'

'

0

748.9

430.2

434.2

249

248.9

498.3

498.2

495

494.9

374.6

0

744.5

744.3

698.9

702.3

495

494.8

985.5

985.1

769.8

769.8

530.6

530.6

480.2

480.1

492.7

492.6

374.1

0

'

'

'

Current portion of long-term debt

620.2

[1]

'

387.3

[1]

382.4

387.3

237.8

240.6

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Interest Rate, Stated Percentage

'

'

'

6.30%

6.30%

6.13%

6.13%

6.00%

6.00%

5.95%

5.95%

1.75%

1.75%

1.50%

1.50%

6.50%

6.50%

2.20%

2.20%

3.95%

3.95%

5.45%

5.45%

4.13%

4.13%

2.75%

2.75%

6.63%

6.63%

6.75%

6.75%

4.50%

4.50%

4.13%

4.13%

4.75%

4.75%

'

'

'

Loss on early extinguishment of debt, net of tax

59.7

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of Interest Rate Derivatives Held

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2

'

'

Long-term debt, less current portion

7,618.40

'

7,865.30

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Early Repayment of Senior Debt

$750

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

[1]

At March 31, 2014, our 6.125% senior notes due January 2015 and 6.3% senior notes due August 2014 are classified as current in the accompanying consolidated balance sheet.

Debt_Shortterm_Debt_Details

Debt - Short-term Debt (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Short-term Debt [Line Items]	'	'
Commercial Paper	$0	$0

Debt_Line_of_Credit_Details

Debt - Line of Credit (Details) (USD $)	3 Months Ended
	Mar. 31, 2014
Line of Credit Facility [Line Items]	'
Unsecured revolving credit agreement	$1,500,000,000
Debt Instrument, Unused Borrowing Capacity, Amount	2,000,000,000
Maximum Amount Of Letters Of Credit Issuable	200,000,000
Facility fee (in hundredths)	0.10%
Minimum [Member]	'
Line of Credit Facility [Line Items]	'
Level the debt to capitalization must be below under the facility agreement	'.5
Minimum [Member] | Line of Credit [Member]	'
Line of Credit Facility [Line Items]	'
Facility fee (in hundredths)	0.07%
Maximum [Member] | Line of Credit [Member]	'
Line of Credit Facility [Line Items]	'
Facility fee (in hundredths)	0.15%
Maximum [Member]	'
Line of Credit Facility [Line Items]	'
Unsecured revolving credit agreement	$2,500,000,000

Capital_Stock_Repurchases_Deta

Capital Stock - Repurchases (Details) (USD $)	3 Months Ended
Share data in Millions, unless otherwise specified	Mar. 31, 2014	Sep. 30, 2013	Mar. 31, 2013
Equity, Class of Treasury Stock [Line Items]	'	'	'
Stock Repurchase Program, Authorized Amount	$1,000,000,000	$750,000,000	'
Stock Repurchased During Period, Shares	7	'	'
Stock Repurchased During Period, Value	465,000,000	'	184,100,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	1,100,000,000	'	'
Treasury Stock [Member]	'	'	'
Equity, Class of Treasury Stock [Line Items]	'	'	'
Stock Repurchased During Period, Value	$465,000,000	'	'

Capital_Stock_Dividends_Detail

Capital Stock - Dividends (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014
Class of Stock Disclosures [Abstract]	'
Dividends Amount Per Share	$0.23
Dividends	$80.50

Capital_Stock_Stock_Units_Deta

Capital Stock - Stock Units (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Minimum Vesting Percentage During Performance Period For Performance Stock Units	0.00%
Maximum Vesting Percentage During Performance Period For Performance Stock Units	200.00%
Vesting Percentage For Market Stock Units Range Minimum	0.00%
Vesting Percentage For Market Stock Units Range Maximum	150.00%
Performance Stock Units [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0.4
Market Stock Units [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0.5
Restricted Stock Units (RSUs) [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	1
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	100.00%
Stock Appreciation Rights (SARs) [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	1.3
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	100.00%
Initial Price	72.26
Estimated Fair Market Value (per unit)	22.68
Expected Term (in years)	'5 years 263 days
Expected Volatility	35.80%
Risk Free Interest Rate	1.74%
Dividend Yield	1.36%

Dividend_Restrictions_and_Stat1

Dividend Restrictions and Statutory Surplus (Details) (Insurance and HMO [Member], USD $)	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Insurance and HMO [Member]	'	'
Dividend Restrictions and Statutory Surplus [Line Items]	'	'
Dividends available	$1,500,000,000	'
Proceeds from dividends received	235,000,000	'
Statutory capital and surplus	$8,200,000,000	$8,400,000,000

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2012	Dec. 31, 2013
Loss Contingencies [Line Items]	'	'	'
Litigation Settlement, Expense	'	$120	'
Settlement of class action litigation, after-tax	'	78	'
Release of litigation-related reserve, after-tax	67	'	'
Release of litigation-related reserve, pre-tax	103	'	'
Charges for changes in our life claim payments practices, net of tax	'	'	35.7
Charge for changes in our life claim payment practices	'	'	$55

Segment_Information_Details

Segment Information (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Segment Reporting Information, Profit (Loss) [Abstract]	'		'
Revenue from external customers	$13,722.10		$9,273.50
Operating Earnings	722	[1],[2]	516.5	[1],[2]
Health Care [Member]	'		'
Segment Reporting Information, Profit (Loss) [Abstract]	'		'
Revenue from external customers	13,131.40		8,723.20
Operating Earnings	719	[2]	513.2	[2]
Group Insurance [Member]	'		'
Segment Reporting Information, Profit (Loss) [Abstract]	'		'
Revenue from external customers	544.4		505.3
Operating Earnings	41.2	[2]	31.9	[2]
Large Case Pension [Member]	'		'
Segment Reporting Information, Profit (Loss) [Abstract]	'		'
Revenue from external customers	46.3		45
Operating Earnings	4.8	[2]	6.2	[2]
Corporate Financing [Member]	'		'
Segment Reporting Information, Profit (Loss) [Abstract]	'		'
Revenue from external customers	0		0
Operating Earnings	($43)	[2]	($34.80)	[2]
[1]	In addition to net realized capital gains (losses) and amortization of other acquired intangible assets, the following other items are excluded from operating earnings because we believe they neither relate to the ordinary course of our business nor reflect our underlying business performance:•We incurred transaction and integration-related costs of $41.9 million ($63.7 million pretax) and $24.6 million ($37.1 million pretax) during the three months ended March 31, 2014 and 2013, respectively, related to the acquisition of Coventry. Transaction costs include advisory, legal and other professional fees which are not deductible for tax purposes and are reflected in our GAAP Consolidated Statements of Income in general and administrative expenses. Transaction costs also include transaction-related payments as well as expenses related to the negative cost of carry associated with the permanent financing that we obtained in November 2012 for the Coventry acquisition. Prior to the Effective Date, the negative cost of carry was excluded from operating earnings. The components of the negative cost of carry are reflected in our GAAP Consolidated Statements of Income in interest expense, net investment income, and general and administrative expenses. On and after the Effective Date, the interest expense and general and administrative expenses associated with the permanent financing are no longer excluded from operating earnings.•In the first quarter of 2014, we incurred a loss on the early extinguishment of long-term debt of $59.7 million ($91.9 million pretax) related to the redemption of our 6.0% senior notes due 2016. •In the fourth quarter of 2012, we recorded a charge of $78.0 million ($120.0 million pretax) related to the settlement of purported class action litigation regarding our payment practices related to out-of-network health care providers. That charge included the estimated cost of legal fees of plaintiffs' counsel and the costs of administering the settlement. In the first quarter of 2014, we exercised our right to terminate the settlement agreement. As a result, we released the reserve established in connection with the settlement agreement, net of amounts due to the settlement administrator, which reduced first quarter 2014 other general and administrative expenses by $67.0 million ($103.0 million pretax). Refer to Note 13 beginning on page 27 for additional information on the termination of the settlement agreement.
[2]	Operating earnings (loss) excludes net realized capital gains or losses, amortization of other acquired intangible assets and the other items described in the reconciliation below.

Segment_Information_Reconcilia

Segment Information - Reconciliation of Operating Earnings (Details) (USD $)	3 Months Ended					9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2012	Sep. 30, 2013	Mar. 31, 2014	Dec. 31, 2013
							Senior Notes, 6.0%, Due 2016 [Member]	Senior Notes, 6.0%, Due 2016 [Member]
Segment Reconciliation [Abstract]	'		'		'	'	'	'
Operating Earnings	$722	[1],[2]	$516.50	[1],[2]	'	'	'	'
Transaction and integration-related costs, after-tax	-41.9		-24.6		'	-24.6	'	'
Loss on early extinguishment of debt, net of tax	59.7		0		'	'	'	'
Release of litigation-related reserve, net of tax	-67		0		'	'	'	'
Amortization of other acquired intangible assets, net of tax	-40.4		-21.1		'	'	'	'
Net realized capital gains, net of tax	18.5		19.3		'	'	'	'
Net income	665.5		490.1		'	'	'	'
Transaction and integration-related costs, pretax	63.7		37.1		'	'	'	'
Loss on early extinguishment of long-term debt	91.9		0		'	'	'	'
Debt Instrument, Interest Rate, Stated Percentage	'		'		'	'	6.00%	6.00%
Settlement of class action litigation, after-tax	'		'		78	'	'	'
Litigation Settlement, Expense	'		'		120	'	'	'
Release of litigation-related reserve, after-tax	-67		'		'	'	'	'
Release of litigation-related reserve, pre-tax	($103)		'		'	'	'	'
[1]	In addition to net realized capital gains (losses) and amortization of other acquired intangible assets, the following other items are excluded from operating earnings because we believe they neither relate to the ordinary course of our business nor reflect our underlying business performance:•We incurred transaction and integration-related costs of $41.9 million ($63.7 million pretax) and $24.6 million ($37.1 million pretax) during the three months ended March 31, 2014 and 2013, respectively, related to the acquisition of Coventry. Transaction costs include advisory, legal and other professional fees which are not deductible for tax purposes and are reflected in our GAAP Consolidated Statements of Income in general and administrative expenses. Transaction costs also include transaction-related payments as well as expenses related to the negative cost of carry associated with the permanent financing that we obtained in November 2012 for the Coventry acquisition. Prior to the Effective Date, the negative cost of carry was excluded from operating earnings. The components of the negative cost of carry are reflected in our GAAP Consolidated Statements of Income in interest expense, net investment income, and general and administrative expenses. On and after the Effective Date, the interest expense and general and administrative expenses associated with the permanent financing are no longer excluded from operating earnings.•In the first quarter of 2014, we incurred a loss on the early extinguishment of long-term debt of $59.7 million ($91.9 million pretax) related to the redemption of our 6.0% senior notes due 2016. •In the fourth quarter of 2012, we recorded a charge of $78.0 million ($120.0 million pretax) related to the settlement of purported class action litigation regarding our payment practices related to out-of-network health care providers. That charge included the estimated cost of legal fees of plaintiffs' counsel and the costs of administering the settlement. In the first quarter of 2014, we exercised our right to terminate the settlement agreement. As a result, we released the reserve established in connection with the settlement agreement, net of amounts due to the settlement administrator, which reduced first quarter 2014 other general and administrative expenses by $67.0 million ($103.0 million pretax). Refer to Note 13 beginning on page 27 for additional information on the termination of the settlement agreement.
[2]	Operating earnings (loss) excludes net realized capital gains or losses, amortization of other acquired intangible assets and the other items described in the reconciliation below.

Reinsurance_Details

Reinsurance (Details) (USD $)	Jan. 31, 2014
In Millions, unless otherwise specified
Reinsurance Disclosures [Abstract]	'
Collateralized excess of loss on resinsurance coverage	$200

Discontinued_Products_Details

Discontinued Products (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013	Dec. 31, 2013
Reserve For Discontinued Products [Roll Forward]	'		'	'
Operating income (loss)	$1,149.70		$750.70	'
Assets:	'		'	'
Investments	23,500.20		'	22,998.80
Collateral received under securities loan agreements	720.7		'	792.6
Total assets	52,119		'	49,871.80
Liabilities:	'		'	'
Policyholders' funds	1,184.10		'	1,188
Total liabilities	37,758		'	35,793.60
Discontinued Products [Member]	'		'	'
Reserve For Discontinued Products [Roll Forward]	'		'	'
Reserve, beginning of period	979.5	[1]	978.5	'
Operating income	5.8		8.8	'
Net realized capital gains	6.3		32.8	'
Reserve, end of period	991.6	[1]	1,020.10	'
Assets:	'		'	'
Investments	3,472.90	[1]	'	3,443.50	[1]
Other Assets	86.6	[1]	'	85.2	[1]
Collateral received under securities loan agreements	175	[1]	'	204.4	[1]
Current and deferred income taxes	17.2	[1]	'	14.4	[1]
Receivable from continuing products	541.3	[1],[2]	'	533.1	[1],[2]
Total assets	4,293	[1]	'	4,280.60	[1]
Liabilities:	'		'	'
Future Policy Benefits	2,765.30	[1]	'	2,804.80	[1]
Reserve for anticipated future losses on discontinued products	991.6	[1]	1,020.10	'
Collateral payable under securities loan agreements	175	[1]	'	204.4	[1]
Other Liabilities	361.1	[1],[3]	'	291.9	[1],[3]
Total liabilities	4,293	[1]	'	4,280.60	[1]
Scheduled Contract Maturities, Settlements And Benefit Payments	97		100	'
Debt And Equity Securities Available For Sale [Member]	'		'	'
Assets:	'		'	'
Investments	20,220.20		'	19,730.40
Debt And Equity Securities Available For Sale [Member] | Discontinued Products [Member]	'		'	'
Assets:	'		'	'
Investments	2,367	[1]	'	2,372.60	[1]
Mortgage Loans [Member]	'		'	'
Assets:	'		'	'
Investments	1,547.60		'	1,549.60
Mortgage Loans [Member] | Discontinued Products [Member]	'		'	'
Assets:	'		'	'
Investments	420.9	[1]	'	407	[1]
Other Investments [Member]	'		'	'
Assets:	'		'	'
Investments	1,732.40		'	1,718.80
Other Investments [Member] | Discontinued Products [Member]	'		'	'
Assets:	'		'	'
Investments	$685	[1]	'	$663.90	[1]
[1]	Assets supporting the discontinued products are distinguished from assets supporting continuing products.
[2]	At the time of discontinuance, a receivable from Large Case Pensions' continuing products was established on the discontinued products balance sheet. This receivable represented the net present value of anticipated cash shortfalls in the discontinued products, which will be funded from continuing products. Interest on the receivable is accrued at the discount rate that was used to calculate the reserve. The offsetting payable, on which interest is similarly accrued, is reflected in continuing products. Interest on the payable generally offsets investment income on the assets available to fund the shortfall. These amounts are eliminated in consolidation.
[3]	Net unrealized capital gains on the available-for-sale debt securities are included in other liabilities and are not reflected in consolidated shareholders’ equity.