Aetna 10-Q 27 Oct 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document shares in Millions	9 Months Ended
	Sep. 30, 2016shares
Entity Information [Line Items]
Entity Registrant Name	AETNA INC /PA/
Entity Central Index Key	1,122,304
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding	350.9

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenue:
Health care premiums		$ 13,524.8	$ 12,834.8	$ 40,623.3	$ 38,711.4
Other premiums		548.5	543.5	1,635.8	1,627.5
Fees and other revenue	[1]	1,455	1,394.5	4,395.5	4,278.5
Net investment income		218.4	213.3	687.1	693.6
Net realized capital gains (losses)		34.8	(33.1)	85.5	(23)
Total revenue		15,781.5	14,953	47,427.2	45,288
Benefits and expenses:
Health care costs	[2]	11,091.8	10,409.5	33,171.6	31,146.3
Current and future benefits		534.9	528.8	1,589.3	1,596.1
Operating expenses:
Selling expenses		408.6	393	1,245.4	1,213.6
General and administrative expenses		2,422.1	2,436.1	7,232	7,231.5
Total operating expenses		2,830.7	2,829.1	8,477.4	8,445.1
Interest expense		189.2	97.6	414.7	257.4
Amortization of other acquired intangible assets		61.4	65.1	187	192
Reduction of reserve for anticipated future losses on discontinued products		0	0	(128.5)	0
Total benefits and expenses		14,708	13,930.1	43,711.5	41,636.9
Income before income taxes		1,073.5	1,022.9	3,715.7	3,651.1
Income taxes:
Current		579.6	535	1,696.6	1,697.7
Deferred		(103.3)	(74.5)	(109)	(119.9)
Total income taxes		476.3	460.5	1,587.6	1,577.8
Net Income including non-controlling interests		597.2	562.4	2,128.1	2,073.3
Less: Net income (loss) attributable to non-controlling interests		(6.7)	2.3	(3.5)	3.9
Net income attributable to Aetna		$ 603.9	$ 560.1	$ 2,131.6	$ 2,069.4
Earnings per common share:
Basic		$ 1.72	$ 1.60	$ 6.07	$ 5.93
Diluted		$ 1.70	$ 1.59	$ 6.02	$ 5.87
Administrative Services Contract Member Co Payments And Plan Sponsor Reimbursements		$ 34	$ 31	$ 93.4	$ 83.6
Pharmaceutical And Processing Costs		342	337.4	983.1	964.6
Insured Member Co Payments		$ 27.3	$ 28	$ 89.4	$ 91.6
[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 $34.0 million and $93.4 million (net of pharmaceutical and processing costs of $342.0 million and $983.1 million) for the three and nine months ended September 30, 2016, respectively, and $31.0 million and $83.6 million (net of pharmaceutical and processing costs of $337.4 million and $964.6 million) for the three and nine months ended September 30, 2015, respectively.
[2]	Health care costs have been reduced by Insured member co-payments related to our mail order and specialty pharmacy operations of $27.3 million and $89.4 million for the three and nine months ended September 30, 2016, respectively, and $28.0 million and $91.6 million for the three and nine months ended September 30, 2015, respectively.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net Income including non-controlling interests		$ 597.2	$ 562.4	$ 2,128.1	$ 2,073.3
Other comprehensive (loss) income		10.8	(42.4)	248.7	(204.2)
Comprehensive Income including non-controlling interests		608	520	2,376.8	1,869.1
Comprehensive income (loss) attributable to non-controlling interests		(6.7)	2.3	(3.5)	3.9
Comprehensive Income attributable to Aetna		614.7	517.7	2,380.3	1,865.2
Net Unrealized Gains (Losses) Previously Impaired Securities [Member]
Net unrealized gains (losses)	[1]	(0.8)	(15.7)	(3.4)	(19.7)
Less: reclassification of gains (losses) to earnings	[1]	(0.3)	(13.2)	(4.1)	(6.8)
Other comprehensive (loss) income	[1]	(0.5)	(2.5)	0.7	(12.9)
Other Securities [Member]
Net unrealized gains (losses)		2.7	(27.5)	403.2	(229.5)
Less: reclassification of gains (losses) to earnings		5.3	(16.6)	19.5	(42.2)
Other comprehensive (loss) income		(2.6)	(10.9)	383.7	(187.3)
Foreign Currency and Derivative Gain (Loss) [Member]
Net unrealized gains (losses)		(0.6)	(39.7)	(176.1)	(36.2)
Less: Foreign currency and derivatives reclassification of losses to earnings		(4.8)	(1)	(11.3)	(2.9)
Other comprehensive (loss) income		4.2	(38.7)	(164.8)	(33.3)
Pension and OPEB Plan [Member]
Less: amortization of net actuarial losses		(10.3)	(10.4)	(31.1)	(31.3)
Less: Amortization of prior service cost		0.6	0.7	2	2
Other comprehensive (loss) income		$ 9.7	$ 9.7	$ 29.1	$ 29.3
[1]	Represents unrealized gains (losses) 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 Compr

Consolidated Statement of Comprehensive Income (Paranthetical) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net Unrealized Gains (Losses) Previously Impaired Securities [Member]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax	[1]	$ (1.2)	$ (24.2)	$ (5.2)	$ (30.3)
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, before Tax	[1]	(0.4)	(20.3)	(6.3)	(10.5)
Other Securities [Member]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax		4.1	(42.3)	620.3	(353.1)
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, before Tax		8.2	(25.5)	30	(64.9)
Foreign Currency and Derivative Gain (Loss) [Member]
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax		(0.9)	(61.1)	(270.9)	(55.7)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment Realized upon Sale or Liquidation, before Tax		(7.5)	(1.5)	(17.4)	(4.4)
Pension and OPEB Plan [Member]
Amortization of net actuarial losses, before tax		(16)	(16)	(47.9)	(48.1)
Amortization of prior service credit, before tax		$ 0.9	$ 1.1	$ 3	$ 3.1
[1]	Represents unrealized gains (losses) 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 ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 19,066.2	$ 2,524.3
Investments	2,982.2	3,014.8
Premiums receivable, net	2,126.7	1,753.1
Other receivables, net	2,942.6	2,443.2
Accrued investment income	231.7	227.7
Income taxes receivable	0	260.4
Other current assets	2,594	2,509.5
Total current assets	29,943.4	12,733
Long-term investments	22,756.1	21,664.8
Reinsurance recoverables	728.3	723.9
Goodwill	10,636.8	10,636.8
Other acquired intangible assets, net	1,502.3	1,688.3
Property and equipment, net	597	629.7
Other long-term assets	1,401	1,269.9
Separate Account Assets	4,317.7	4,035.1
Total assets	71,882.6	53,381.5
Current liabilities:
Health care costs payable	6,873.1	6,305.7
Future policy benefits	653.6	671.8
Unpaid claims	764.8	772.3
Unearned premiums	1,843	549.2
Policyholders' funds	2,602.6	2,262.5
Current portion of long-term debt	640.1	0
Income taxes payable	242.5	0
Accrued expenses and other current liabilities	5,715.8	4,920
Total current liabilities	19,335.5	15,481.5
Future policy benefits	5,992.9	6,268.2
Unpaid claims	1,710.6	1,655.6
Policyholders' funds	948.1	885.6
Long-term debt, less current portion	20,022.1	7,785.4
Deferred income taxes	243.1	177.4
Other long-term liabilities	968.1	914.1
Separate Accounts liabilities	4,317.7	4,035.1
Total liabilities	53,538.1	37,202.9
Commitments and contingencies (Note 14)
Shareholders' equity:
Common stock ($.01 par value; 2.5 billion shares authorized and 350.9 million shares issued and outstanding in 2016; 2.5 billion shares authorized and 349.5 million shares issued and outstanding in 2015) and additional paid-in capital	4,699.3	4,647.2
Retained earnings	14,666	12,797.4
Accumulated other comprehensive loss	(1,081.6)	(1,330.3)
Total Aetna shareholders' equity	18,283.7	16,114.3
Non-controlling Interests	60.8	64.3
Total equity	18,344.5	16,178.6
Total liabilities and equity	$ 71,882.6	$ 53,381.5

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Paranthetical) - $ / shares	Sep. 30, 2016	Dec. 31, 2015
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	2,500,000,000	2,500,000,000
Common Stock, Shares, Issued	350,900,000	349,500,000
Common Stock, Shares, Outstanding	350,900,000	349,500,000

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Millions	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]
Stockholders' Equity Attributable to Noncontrolling Interest at beginning of period at Dec. 31, 2014							$ 69.2
Total equity at beginning of period at Dec. 31, 2014	$ 14,551.8
Balance at beginning of period at Dec. 31, 2014			$ 4,542.2	$ 11,051.7	$ (1,111.3)	$ 14,482.6
Balance at beginning of period (in shares) at Dec. 31, 2014		349,800,000
Comprehensive income:
Net income attributable to Aetna	2,069.4	$ 0	0	2,069.4	0	2,069.4
Net income (loss) attributable to non-controlling interest	3.9						3.9
Net Income including non-controlling interests	2,073.3
Other increases (decreases) in noncontrolling interests	(9.4)	0	0	0	0	0	(9.4)
Other comprehensive (loss) income	(204.2)	$ 0	0	0	(204.2)	(204.2)	0
Common shares issued for benefit plans, net of employee tax withholdings		1,900,000
Common shares issued for benefit plans, net of employee tax withholdings	78.4		78.4	0	0	78.4	0
Repurchases of common shares	(296.3)		(0.1)	(296.2)	0	(296.3)	0
Repurchases of common shares (in shares)		(3,000,000)
Dividends declared	(261.1)	$ 0	0	(261.1)	0	(261.1)	0
Balance at end of period at Sep. 30, 2015			4,620.5	12,563.8	(1,315.5)	15,868.8
Balance at end of period (in shares) at Sep. 30, 2015		348,700,000
Total equity at end of period at Sep. 30, 2015	15,932.5
Stockholders' Equity Attributable to Noncontrolling Interest at end of period at Sep. 30, 2015							63.7
Stockholders' Equity Attributable to Noncontrolling Interest at beginning of period at Dec. 31, 2015	64.3						64.3
Total equity at beginning of period at Dec. 31, 2015	16,178.6
Balance at beginning of period at Dec. 31, 2015	$ 16,114.3		4,647.2	12,797.4	(1,330.3)	16,114.3
Balance at beginning of period (in shares) at Dec. 31, 2015	349,500,000	349,500,000
Comprehensive income:
Net income attributable to Aetna	$ 2,131.6	$ 0	0	2,131.6	0	2,131.6
Net income (loss) attributable to non-controlling interest	(3.5)						(3.5)
Net Income including non-controlling interests	2,128.1
Other increases (decreases) in noncontrolling interests	0	0	0	0	0	0	0
Other comprehensive (loss) income	248.7	$ 0	0	0	248.7	248.7	0
Common shares issued for benefit plans, net of employee tax withholdings		1,400,000
Common shares issued for benefit plans, net of employee tax withholdings	52.1		52.1	0	0	52.1	0
Repurchases of common shares	0
Dividends declared	(263)	$ 0	0	(263)	0	(263)	0
Balance at end of period at Sep. 30, 2016	$ 18,283.7		$ 4,699.3	$ 14,666	$ (1,081.6)	$ 18,283.7
Balance at end of period (in shares) at Sep. 30, 2016	350,900,000	350,900,000
Total equity at end of period at Sep. 30, 2016	$ 18,344.5
Stockholders' Equity Attributable to Noncontrolling Interest at end of period at Sep. 30, 2016	$ 60.8						$ 60.8

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net Income including non-controlling interests	$ 2,128.1	$ 2,073.3
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized capital (gains) losses	(85.5)	23
Depreciation and amortization	510.8	499
Debt fair value amortization	(22.2)	(22.7)
Amortization of interest rate hedges	11.9	4.4
Equity in earnings of affiliates, net	1.4	(34.1)
Stock-based compensation expense	147.4	138.5
Reduction of reserve for anticipated future losses on discontinued products	(128.5)	0
Amortization of net investment premium	62.1	61.2
Changes in assets and liabilities:
Accrued investment income	(4)	(2.5)
Premiums due and other receivables	(575.8)	(681.6)
Income taxes	386.9	270.2
Other assets and other liabilities	332.4	89.9
Health care and insurance liabilities	1,856	337
Net cash provided by operating activities	4,621	2,755.6
Cash flows used for investing activities:
Proceeds from sales and maturities of investments	10,746.6	9,066.2
Cost of investments	(10,875.6)	(9,514.2)
Additions to property, equipment and software	(196.9)	(287)
Cash used for acquisitions, net of cash acquired	0	(20.6)
Net cash provided by (used for) investing activities	(325.9)	(755.6)
Cash flows used for financing activities:
Issuance of long-term debt	12,885.7	0
Repayment of long-term debt	0	(228.8)
Net (repayment) issuance of short-term debt	0	(500)
Deposits and interest credited to investment contracts net of (withdrawals)	0.4	(35.5)
Common shares issued under benefit plans, net	(103.1)	(106.1)
Stock-based compensation tax benefits	0	39.1
(Settlements) proceeds from repurchase agreements	0	(201.7)
Common shares repurchased	0	(296.3)
Dividends paid to shareholders	(262.7)	(261.5)
Net (payment) receipt on interest rate derivatives	(273.5)	(23.7)
(Distributions) contributions, non-controlling interests	0	(9.4)
Net cash provided by (used for) financing activities	12,246.8	(1,623.9)
Net increase (decrease) in cash and cash equivalents	16,541.9	376.1
Cash and cash equivalents, beginning of period	2,524.3	1,420.4
Cash and cash equivalents, end of period	19,066.2	1,796.5
Supplemental cash flow information:
Interest paid	214.2	213
Income taxes paid	$ 1,200.7	$ 1,268.1

Organization

Organization	9 Months Ended
	Sep. 30, 2016
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 business products and services, such as Accountable Care Solutions, that complement and enhance our medical products. 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 networks in select geographies. • Group Insurance primarily includes group life insurance and group disability products. Group life insurance products are offered on an Insured basis. Group disability products are offered to employers on both an Insured and an ASC basis. Group Insurance also includes long-term care products that were offered primarily on an Insured basis. 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 18 for additional information).

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2016
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 2015 Annual Report on Form 10-K (our “2015 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 2015 Annual Report, unless the information contained in those disclosures materially changed and is required by GAAP. The Company has evaluated subsequent events that occurred after September 30, 2016 through the date the financial statements were issued and determined there were no subsequent events to disclose. Reclassifications Certain reclassifications were made to 2015 financial information to conform with the 2016 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. New Accounting Standards Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period Effective January 1, 2016, we adopted new accounting guidance related to the accounting for share-based payments when the terms of an award provide that a performance target could be achieved after the requisite service period. This guidance clarifies that awards with these provisions should be treated as performance conditions that affect vesting, and do not impact the award’s estimated grant-date fair value. The adoption of this new guidance did not have an impact on our financial position or operating results. Determining Whether the Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share Is More Akin to Debt or to Equity Effective January 1, 2016, we adopted new accounting guidance related to the approach used in determining whether the host contract in a hybrid financial instrument issued in the form of a share is more akin to debt or equity. The adoption of this new guidance did not have a material impact on our financial position or operating results. Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items Effective January 1, 2016, we adopted new accounting guidance related to the presentation of extraordinary items. The new guidance eliminates the concept of extraordinary items, which are events that are both unusual and infrequent. Presentation and disclosure of items that are unusual or infrequent will be retained, and will be expanded to include items that are both unusual and infrequent. The adoption of this new guidance did not have a material impact on our financial position or operating results. Amendments to the Consolidation Analysis Effective January 1, 2016, we adopted new accounting guidance related to the evaluation of consolidation for certain legal entities. The new guidance changes how a reporting entity assesses consolidation, including whether an entity is considered a variable interest entity, determination of the primary beneficiary and how related parties are considered in the analysis. The adoption of this new guidance required more of our other investments to be considered variable interest entities; however, it did not require additional investments to be consolidated or de-consolidated or have a material impact on our financial position or operating results. Our variable interest entity disclosures as of December 31, 2015 were retrospectively adjusted to conform with the new accounting guidance. Refer to Note 7 for further discussion. Simplifying the Presentation of Debt Issuance Costs Effective January 1, 2016, we adopted new accounting guidance related to the financial statement presentation of all debt issuance costs, including those related to line-of-credit arrangements. The new guidance requires debt issuance costs to be presented as a direct deduction from the carrying amount of our debt liability, consistent with the approach used for debt premiums or discounts. We also elected to report debt issuance costs associated with any line-of-credit arrangements as a direct deduction from the carrying amount of our debt liability. Amortization of debt issuance costs also will be reported in our statements of income in interest expense, as opposed to general and administrative expenses. We are applying this new guidance on a full retrospective basis, with all prior periods restated for the new presentation. The adoption of this new guidance requires certain reclassifications in our financial statements and did not have a material impact on our financial position or operating results. As a result of adopting this guidance, we reclassified $43 million of other current and long-term assets as a reduction of long-term debt on our balance sheet at December 31, 2015. Additionally, we reclassified an immaterial amount of general and administrative expenses into interest expense for the three and nine months ended September 30, 2015. Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement Effective January 1, 2016, we adopted new accounting guidance related to the evaluation of fees paid by a customer in a cloud computing arrangement. The new guidance provides additional guidance that aids in determining whether a cloud computing arrangement contains a software license. Arrangements that do not contain a software license must be accounted for as a service contract. If a software license is included in the cloud computing arrangement, the license element must be accounted for consistent with the acquisition of a software license. The adoption of this new guidance did not have a material impact on our financial position or operating results. Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent) Effective January 1, 2016, we adopted new accounting guidance related to the presentation of investments in certain entities that calculate net asset value per share (or its equivalent). The new guidance removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share practical expedient. This new guidance is applicable to certain of our investments that reside in our separate accounts and employee benefit plans. The adoption of this new guidance did not have a material impact on our financial position or operating results. Simplifying the Accounting for Measurement-Period Adjustments Effective January 1, 2016, we adopted new accounting guidance related to the recognition of adjustments to provisional amounts that are identified during the measurement period in a business combination. The new guidance eliminates the requirement to retrospectively account for measurement-period adjustments as part of a business combination and permits such adjustments to be recognized in the period in which the adjustment was determined. The adoption of this new guidance did not have a material impact on our financial position or operating results. Improvements to Employee Share-Based Payment Accounting Effective April 1, 2016, we elected to early adopt new accounting guidance related to the accounting for and financial statement presentation of employee share-based payments. As a result of adopting this new guidance, we recognized an immaterial amount of excess tax benefits in our statements of income that previously would have been recorded in additional paid-in capital for the three and nine months ended September 30, 2016, and correspondingly reclassified the excess tax benefits for the nine months ended September 30, 2016 from financing activities to operating activities in our statements of cash flows. We applied each of these provisions on a prospective basis, with adjustments reflected as of January 1, 2016, and prior periods were not retrospectively adjusted. Our ability under the new guidance to withhold more shares to satisfy our statutory income tax obligations had no impact on our financial statements and was adopted on a modified retrospective basis. We continue to estimate expected forfeitures of share-based payment awards in each period. Future Application of Accounting Standards Disclosure of Uncertainties About an Entity’s Ability to Continue as a Going Concern Effective December 31, 2016, we will adopt new accounting guidance related to management’s evaluation of whether there is substantial doubt about an entity’s ability to continue as a going concern and the related disclosures. The adoption of this new guidance will not have a material impact on our financial position or operating results. Disclosures about Short-Duration Insurance Contracts Effective December 31, 2016, we will adopt new accounting guidance related to the disclosure of short-duration insurance contracts. The new guidance requires insurance companies that issue short-duration contracts to include additional disclosures about those insurance liabilities, including disaggregation of certain disclosures, as appropriate. The adoption of this new guidance will not have a material impact on our financial position or operating results, however, the new guidance will require additional disclosure for our short-duration insurance liabilities that reside in our Health Care and Group Insurance segments. Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships Effective January 1, 2017, we will adopt new accounting guidance clarifying that the novation of a derivative contract in a hedge accounting relationship does not, in and of itself, require dedesignation of the hedge accounting relationship. The adoption of this new guidance is not expected to have a material impact on our financial position or operating results. Contingent Put and Call Options in Debt Instruments Effective January 1, 2017, we will adopt new accounting guidance related to the assessment of embedded contingent put or call options in debt instruments. The new guidance clarifies that assessment of whether an embedded contingent put or call option is clearly and closely related to the debt host requires only an analysis of the four-step decision sequence. The adoption of this new guidance is not expected to have a material impact on our financial position or operating results. Simplifying the Transition to the Equity Method of Accounting Effective January 1, 2017, we will adopt new accounting guidance related to the accounting for investments that subsequently qualify for the equity method of accounting. The new accounting guidance eliminates the requirement that an entity retrospectively apply the equity method of accounting to an investment previously accounted for by another method when we subsequently obtain significant influence. The adoption of this new guidance is not expected to have a material impact on our financial position or operating results. Revenue from Contracts with Customers Effective January 1, 2018, we will adopt new accounting guidance related to revenue recognition from contracts with customers. This new guidance removes most industry-specific revenue recognition requirements (insurance contracts are not covered by this guidance) and requires that an entity recognize revenue for the transfer of goods or services to a customer at an amount that reflects the consideration to which an entity expects to be entitled in exchange for those goods or services. The new guidance also requires additional disclosures regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts. The new guidance allows an entity to adopt the standard either through a full retrospective approach or a modified retrospective approach with a cumulative effect adjustment to retained earnings. Early adoption of this new guidance is permitted as of January 1, 2017. We are still assessing the impact of this new guidance on our financial position and operating results in addition to evaluating the transition method we will use when we adopt this new guidance. Recognition and Measurement of Financial Assets and Financial Liabilities Effective January 1, 2018, we will adopt new accounting guidance related to the recognition and measurement of financial assets and financial liabilities. Under the new guidance, all equity investments in unconsolidated entities will be measured at fair value with changes in fair value recognized in net income. A reporting entity may elect to report equity investments without a readily determinable fair value at cost. The new guidance also revises certain disclosures regarding financial assets and liabilities. The adoption of this new guidance is not expected to have a material impact on our financial position or operating results. Classification of Certain Cash Receipts and Cash Payments in the Statement of Cash Flows Effective January 1, 2018, we will adopt new accounting guidance which clarifies the classification of certain cash receipts and payments within our statement of cash flows. We are still assessing the impact of this new guidance on our statement of cash flows. Leases Effective January 1, 2019, we will adopt new accounting guidance related to the recognition, measurement and disclosure requirements for leases. Under the new guidance, lessees will be required to recognize a right-of-use asset and corresponding lease liability on their balance sheets for all leases other than those that meet the definition of a short-term lease. The new guidance also revises certain disclosure requirements regarding leases. We are still assessing the impact of this new guidance on our financial position and operating results. Measurement of Credit Losses on Financial Instruments Effective January 1, 2020, we will adopt new accounting guidance related to the measurement of credit losses on financial assets and certain other instruments. The new guidance requires the use of a new forward-looking expected loss impairment model for trade and other receivables, held-to-maturity debt securities, loans and other instruments; requires impairments and recoveries for available-for-sale debt securities to be recorded through an allowance account; and revises certain disclosure requirements. We are still assessing the impact of this new guidance on our financial position and operating results.

Proposed Acquisition

Proposed Acquisition	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
Business Combination Disclosure	3. Proposed Acquisition of Humana On July 2, 2015, we entered into a definitive agreement (as it may be amended, the "Merger Agreement") to acquire Humana Inc. ("Humana") in a transaction valued at approximately $37 billion , based on the closing price of Aetna common shares on July 2, 2015, including the assumption of Humana debt and Humana cash and cash equivalents. Under the terms of the Merger Agreement, Humana stockholders will receive $125.00 in cash and 0.8375 Aetna common shares for each Humana share. On October 19, 2015, Aetna and Humana each obtained the approval of their respective shareholders necessary for our proposed acquisition of Humana (the “Humana Acquisition”). On June 24, 2016, in accordance with the terms of the Merger Agreement, each of Aetna and Humana delivered a written notice to the other that such party had elected to extend the “End Date” (as defined in the Merger Agreement) from June 30, 2016 to December 31, 2016. In June 2016, we issued $13 billion of senior notes (collectively, the “2016 Humana-related senior notes”) to partially fund the Humana Acquisition. If the Humana Acquisition has not been completed by December 31, 2016 (or such later date to which the “End Date” under the Merger Agreement is extended by agreement between us and Humana) or if, prior to such date, the Merger Agreement is terminated, we must redeem $10.2 billion aggregate principal amount of certain of the 2016 Humana-related senior notes at a redemption price equal to 101% of the aggregate principal amount of those notes plus accrued and unpaid interest and recognize the entire unamortized portion of the related cash flow hedge losses, debt issuance costs and debt issuance discounts in our net income upon such redemption. On July 21, 2016, the U.S. Department of Justice (the “DOJ”) and certain state attorneys general filed a civil complaint in the U.S. District Court for the District of Columbia against us and Humana charging that the Humana Acquisition would violate Section 7 of the Clayton Antitrust Act, and seeking a permanent injunction to prevent Aetna from acquiring Humana (the “DOJ litigation”). The trial in the DOJ litigation is scheduled to begin during December 2016, and the trial court decision in the DOJ litigation is expected in January 2017. We plan to vigorously defend the Humana Acquisition. In order to address the DOJ’s perceived competitive concerns regarding Medicare Advantage, on August 2, 2016, we entered into a definitive agreement (as it may be amended, the “Aetna APA”) to sell for cash to Molina Healthcare, Inc. (“Molina”) certain of our Medicare Advantage assets. Also on August 2, 2016, Humana entered into a substantially identical definitive agreement (as it may be amended, the “Humana APA”) to sell for cash to Molina certain of Humana’s Medicare Advantage assets. The sale price under the Aetna APA is approximately $76 million , based on the estimated membership in the plans that are involved in the transaction. The transactions contemplated by the Aetna APA and the Humana APA remain subject to the completion of the Humana Acquisition, the resolution of the DOJ litigation, CMS approvals and actions, and customary closing conditions, including approvals of state departments of insurance and other regulators. The Humana Acquisition remains subject to resolution of the DOJ litigation and customary closing conditions, including approvals of state departments of insurance and other regulators, and, depending upon the resolution of the DOJ litigation, the completion of the transactions contemplated by the Aetna APA and the Humana APA. Neither the Humana Acquisition nor the transactions contemplated by the Aetna APA have been reflected in these financial statements.

Earnings Per Common Share

Earnings Per Common Share	9 Months Ended
	Sep. 30, 2016
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 and nine months ended September 30, 2016 and 2015 are as follows: Three Months Ended Nine Months Ended September 30, September 30, (Millions, except per common share data) 2016 2015 2016 2015 Net income attributable to Aetna $ 603.9 $ 560.1 $ 2,131.6 $ 2,069.4 Weighted average shares used to compute basic EPS 351.4 349.2 351.1 349.2 Dilutive effect of outstanding stock-based compensation awards 2.9 3.3 3.0 3.3 Weighted average shares used to compute diluted EPS 354.3 352.5 354.1 352.5 Basic EPS $ 1.72 $ 1.60 $ 6.07 $ 5.93 Diluted EPS $ 1.70 $ 1.59 $ 6.02 $ 5.87 The stock-based compensation awards excluded from the calculation of diluted EPS for the three and nine months ended September 30, 2016 and 2015 are as follows: Three Months Ended Nine Months Ended September 30, September 30, (Millions) 2016 2015 2016 2015 Stock appreciation rights (“SARs”) (1) — .1 .1 .7 Other stock-based compensation awards (2) .7 .5 .8 .8 (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) Performance stock units ("PSUs"), certain market stock units ("MSUs") with performance conditions, and performance stock appreciation rights ("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

Operating Expenses	9 Months Ended
	Sep. 30, 2016
Operating Expenses [Abstract]
Operating Expenses	5. Operating Expenses For the three and nine months ended September 30, 2016 and 2015 , 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: Three Months Ended Nine Months Ended September 30, September 30, (Millions) 2016 2015 2016 2015 Selling expenses $ 408.6 $ 393.0 $ 1,245.4 $ 1,213.6 General and administrative expenses: Salaries and related benefits 1,258.1 1,242.3 3,737.2 3,665.3 Other general and administrative expenses (1) 1,164.0 1,193.8 3,494.8 3,566.2 Total general and administrative expenses 2,422.1 2,436.1 7,232.0 7,231.5 Total operating expenses $ 2,830.7 $ 2,829.1 $ 8,477.4 $ 8,445.1 (1) The three and nine months ended September 30, 2016 include estimated fees mandated by the ACA (as defined in Note 8 ) comprised primarily of the health insurer fee of $210.6 million and $627.6 million , respectively, and our estimated contribution to the funding of the ACA’s reinsurance program of $29.6 million and $88.6 million , respectively. The three and nine months ended September 30, 2015 include estimated fees mandated by the ACA comprised primarily of the health insurer fee of $209.7 million and $642.2 million , respectively, and our estimated contribution to the funding of the ACA’s reinsurance program of $51.6 million and $157.4 million , respectively.

Cash and Cash Equivalents (Note

Cash and Cash Equivalents (Notes)	9 Months Ended
	Sep. 30, 2016
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents, and Short-term Investments [Text Block]	6. Cash and Cash Equivalents Cash and cash equivalents include approximately $13 billion of highly rated money market fund investments related to the net proceeds received from the 2016 Humana-related senior notes we issued in June 2016 to partially fund the Humana Acquisition. These money market funds have average maturities of 60 days or less and are redeemable daily at par value plus accrued dividends with specified yield rates.

Investments

Investments	9 Months Ended
	Sep. 30, 2016
Investments [Abstract]
Investments	7. Investments Total investments at September 30, 2016 and December 31, 2015 were as follows: September 30, 2016 December 31, 2015 (Millions) Current Long-term Total Current Long-term Total Debt and equity securities available for sale $ 2,813.8 $ 19,746.8 $ 22,560.6 $ 2,877.1 $ 18,445.9 $ 21,323.0 Mortgage loans 168.4 1,350.1 1,518.5 126.9 1,426.8 1,553.7 Other investments — 1,659.2 1,659.2 10.8 1,792.1 1,802.9 Total investments $ 2,982.2 $ 22,756.1 $ 25,738.3 $ 3,014.8 $ 21,664.8 $ 24,679.6 Debt and Equity Securities Debt and equity securities available for sale at September 30, 2016 and December 31, 2015 were as follows: (Millions) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value September 30, 2016 Debt securities: U.S. government securities $ 1,688.6 $ 111.0 $ (.7 ) $ 1,798.9 States, municipalities and political subdivisions 4,941.5 312.1 (6.9 ) 5,246.7 U.S. corporate securities 8,169.9 627.7 (10.2 ) 8,787.4 Foreign securities 2,969.5 266.6 (6.2 ) 3,229.9 Residential mortgage-backed securities 835.0 25.5 (.5 ) 860.0 Commercial mortgage-backed securities 1,357.4 33.7 (2.7 ) (1) 1,388.4 Other asset-backed securities 1,066.8 13.7 (8.2 ) (1) 1,072.3 Redeemable preferred securities 23.2 5.7 — 28.9 Total debt securities 21,051.9 1,396.0 (35.4 ) 22,412.5 Equity securities 127.0 24.3 (3.2 ) 148.1 Total debt and equity securities (2) $ 21,178.9 $ 1,420.3 $ (38.6 ) $ 22,560.6 December 31, 2015 Debt securities: U.S. government securities $ 1,803.5 $ 68.8 $ (.6 ) $ 1,871.7 States, municipalities and political subdivisions 4,889.5 244.3 (9.3 ) 5,124.5 U.S. corporate securities 7,981.5 339.5 (146.6 ) 8,174.4 Foreign securities 2,910.2 148.3 (61.4 ) 2,997.1 Residential mortgage-backed securities 914.6 16.6 (6.3 ) 924.9 Commercial mortgage-backed securities 1,262.4 17.2 (9.0 ) (1) 1,270.6 Other asset-backed securities 910.4 3.1 (19.2 ) (1) 894.3 Redeemable preferred securities 33.0 11.5 — 44.5 Total debt securities 20,705.1 849.3 (252.4 ) 21,302.0 Equity securities 22.8 4.1 (5.9 ) 21.0 Total debt and equity securities (2) $ 20,727.9 $ 853.4 $ (258.3 ) $ 21,323.0 (1) At September 30, 2016 and December 31, 2015 , we held securities for which we previously recognized $4.9 million and $5.4 million , respectively, of non-credit related impairments in accumulated other comprehensive loss. These securities had a net unrealized capital gain at September 30, 2016 and December 31, 2015 of $0.9 million and $1.9 million , respectively. (2) Investment risks associated with our experience-rated and discontinued products generally do not impact our operating results (refer to Note 18 for additional information on our accounting for discontinued products). At September 30, 2016 , debt and equity securities with a fair value of approximately $3.1 billion , gross unrealized capital gains of $327.8 million and gross unrealized capital losses of $6.6 million and, at December 31, 2015 , debt and equity securities with a fair value of approximately $3.0 billion , gross unrealized capital gains of $208.7 million and gross unrealized capital losses of $68.0 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 September 30, 2016 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 $ 1,419.0 One year through five years 6,789.4 After five years through ten years 5,290.1 Greater than ten years 5,593.3 Residential mortgage-backed securities 860.0 Commercial mortgage-backed securities 1,388.4 Other asset-backed securities 1,072.3 Total $ 22,412.5 Mortgage-Backed and Other Asset-Backed Securities All of our residential mortgage-backed securities at September 30, 2016 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 September 30, 2016 , our residential mortgage-backed securities had an average credit quality rating of AAA and a weighted average duration of 2.9 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 loss severity and probability of default. At September 30, 2016 , these securities had an average credit quality rating of AAA and a weighted average duration of 6.8 years. Our other asset-backed securities have a variety of underlying collateral (e.g., automobile loans, credit card receivables, home equity loans and commercial loans). Significant market observable inputs used to value these securities include the unemployment rate, loss severity and probability of default. At September 30, 2016 , these securities had an average credit quality rating of AA- and a weighted average duration of 1.4 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 September 30, 2016 and December 31, 2015 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 Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses September 30, 2016 Debt securities: U.S. government securities $ 107.3 $ .4 $ 10.2 $ .3 $ 117.5 $ .7 States, municipalities and political subdivisions 545.0 4.5 125.9 2.4 670.9 6.9 U.S. corporate securities 439.2 1.6 129.2 8.6 568.4 10.2 Foreign securities 266.0 2.0 88.8 4.2 354.8 6.2 Residential mortgage-backed securities 32.5 .1 37.2 .4 69.7 .5 Commercial mortgage-backed securities 396.5 2.7 4.8 — 401.3 2.7 Other asset-backed securities 158.4 2.1 142.1 6.1 300.5 8.2 Total debt securities 1,944.9 13.4 538.2 22.0 2,483.1 35.4 Equity securities 34.6 .9 2.7 2.3 37.3 3.2 Total debt and equity securities (1) $ 1,979.5 $ 14.3 $ 540.9 $ 24.3 $ 2,520.4 $ 38.6 December 31, 2015 Debt securities: U.S. government securities $ 66.8 $ .2 $ 12.6 $ .4 $ 79.4 $ .6 States, municipalities and political subdivisions 714.2 6.1 91.6 3.2 805.8 9.3 U.S. corporate securities 3,168.7 130.8 144.3 15.8 3,313.0 146.6 Foreign securities 1,102.4 50.4 89.2 11.0 1,191.6 61.4 Residential mortgage-backed securities 328.7 2.9 89.5 3.4 418.2 6.3 Commercial mortgage-backed securities 562.0 8.6 23.8 .4 585.8 9.0 Other asset-backed securities 653.5 15.6 67.1 3.6 720.6 19.2 Total debt securities 6,596.3 214.6 518.1 37.8 7,114.4 252.4 Equity securities — 5.0 1.3 .9 1.3 5.9 Total debt and equity securities (1) $ 6,596.3 $ 219.6 $ 519.4 $ 38.7 $ 7,115.7 $ 258.3 (1) At September 30, 2016 and December 31, 2015 , debt and equity securities in an unrealized capital loss position of $6.6 million and $68.0 million , respectively, and with related fair value of $238.6 million and $966.2 million , 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 September 30, 2016 , 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 amortized cost basis. The maturity dates for debt securities in an unrealized capital loss position at September 30, 2016 were as follows: Supporting discontinued and experience-rated products Supporting remaining products Total (Millions) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Due to mature: Less than one year $ — $ — $ 135.9 $ .5 $ 135.9 $ .5 One year through five years 4.1 — 657.7 5.3 661.8 5.3 After five years through ten years 78.8 .8 357.1 4.9 435.9 5.7 Greater than ten years 96.1 4.0 381.9 8.5 478.0 12.5 Residential mortgage-backed securities 5.2 — 64.5 .5 69.7 .5 Commercial mortgage-backed securities 51.7 .4 349.6 2.3 401.3 2.7 Other asset-backed securities — — 300.5 8.2 300.5 8.2 Total $ 235.9 $ 5.2 $ 2,247.2 $ 30.2 $ 2,483.1 $ 35.4 Net realized capital gains for the three and nine months ended September 30, 2016 and 2015 , excluding amounts related to experience-rated contract holders and discontinued products, were as follows: Three Months Ended Nine Months Ended September 30, September 30, (Millions) 2016 2015 2016 2015 OTTI losses on debt securities recognized in earnings $ (.4 ) $ (21.0 ) $ (10.1 ) $ (31.0 ) Other net realized capital gains (losses) 35.2 (12.1 ) 95.6 8.0 Net realized capital gains (losses) $ 34.8 $ (33.1 ) $ 85.5 $ (23.0 ) The net realized capital gains for the three and nine months ended September 30, 2016 were primarily attributable to gains from the sales of debt securities. The net realized capital losses for the three and nine months ended September 30, 2015 were primarily attributable to yield-related OTTI on debt securities. The net realized capital losses for the nine months ended September 30, 2015 were partially offset by gains from the sales of debt securities. We had no individually material realized capital losses on debt or equity securities that impacted our operating results during three or nine months ended September 30, 2016 or 2015 . 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 and nine months ended September 30, 2016 and 2015 were as follows: Three Months Ended Nine Months Ended September 30, September 30, (Millions) 2016 2015 2016 2015 Proceeds on sales $ 1,481.4 $ 1,275.4 $ 4,836.2 $ 3,766.6 Gross realized capital gains 31.0 12.7 130.8 58.3 Gross realized capital losses 2.6 19.1 37.7 41.5 Mortgage Loans Our mortgage loans are collateralized by commercial real estate. During the three and nine months ended September 30, 2016 and 2015 we had the following activity in our mortgage loan portfolio: Three Months Ended Nine Months Ended September 30, September 30, (Millions) 2016 2015 2016 2015 New mortgage loans $ 65.7 $ 132.6 $ 154.5 $ 169.7 Mortgage loans fully repaid 55.6 37.1 141.9 96.1 Mortgage loans foreclosed 7.5 — 7.5 9.0 At September 30, 2016 and December 31, 2015 , we had no material problem, restructured or potential problem mortgage loans. We also had no material impairment reserves on these loans at September 30, 2016 or December 31, 2015 . 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 Category 7 represents loans where collections are potentially at risk. The vast majority of our mortgage loans fall into the Category 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. Categories 5 and 6 represent 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. At both September 30, 2016 and December 31, 2015 we did not have any loans in Category 7. Based upon our most recent assessments at September 30, 2016 and December 31, 2015 , our mortgage loans were given the following credit quality indicators: (In Millions, except credit ratings indicator) September 30, December 31, 1 $ 48.6 $ 65.8 2 to 4 1,452.6 1,466.9 5 and 6 17.3 21.0 Total $ 1,518.5 $ 1,553.7 Variable Interest Entities As discussed in Note 2 , we adopted the guidance of Accounting Standards Update (ASU) No. 2015-02, Amendments to the Consolidation Analysis (Topic 810) effective January 1, 2016 . As a result of adopting the new guidance, we have investments in certain hedge fund and private equity investments and real estate partnerships that are considered Variable Interest Entities (“VIE’s”). We do not have a future obligation to fund losses or debts on behalf of these investments; however, we may voluntarily contribute funds. In evaluating whether we are the primary beneficiary of a VIE, we considered several factors, including whether we (a) have the power to direct the activities that most significantly impact the VIE’s economic performance and (b) the obligation to absorb losses and the right to receive benefits that could potentially be significant to the VIE. Variable Interest Entities - Primary Beneficiary Upon adoption of the new guidance, we identified one hedge fund investment previously consolidated as a Voting Interest Entity in our balance sheets and operating results that is determined to be a VIE under the new guidance. The investment represents a majority owned hedge fund where we are the investment manager and have the power to direct the activities that most significantly impact the VIE’s economic performance, including determining the hedge fund’s investment strategy. Accordingly, we are the primary beneficiary and will continue to consolidate the investment in our financial results. The fund invests in additional hedge funds that are VIEs; however, we are not the primary beneficiary of these underlying funds as discussed in further detail below. Substantially all of the assets of the VIE hedge fund are comprised of hedge fund investments reported as long-term investments on our balance sheets. The VIE hedge fund had no material liabilities at September 30, 2016 or December 31, 2015 . The total amount of the VIE hedge fund’s assets included in long term investments on our balance sheets at September 30, 2016 and December 31, 2015 were $500 million and $477 million , respectively. Variable Interest Entities - Other Variable Interest Holder Our involvement with VIEs where we are not determined to be the primary beneficiary consist of the following: Hedge fund and private equity investments - We invest in hedge fund and private equity investments in order to generate investment returns for our investment portfolio supporting our businesses. Real estate partnerships - We invest in various real estate partnerships including those that construct, own and manage low-income housing developments. For the low income housing development investments, substantially all of the projected benefits to us are from tax credits and other tax benefits. We are not the primary beneficiary of these investments because the nature of our involvement with the activities of the VIEs does not give us the power to direct the activities that most significantly impact their economic performance. We record the amount of our investment as long-term investments on our balance sheets and recognize our share of each VIE’s income or losses in earnings. Our maximum exposure to loss is limited to our investment balances as disclosed below and the risk of recapture of tax credits related to real estate partnerships previously recognized, which we do not consider significant. The total amount of other variable interest holder VIE assets included in long term investments on our balance sheets at September 30, 2016 and December 31, 2015 were as follows: (Millions) September 30, December 31, 2015 Hedge fund investments $ 407.7 $ 418.1 Private equity investments 437.4 443.3 Real estate partnerships 287.3 253.3 Total $ 1,132.4 $ 1,114.7 The carrying value of the total assets and liabilities of our other variable interest holder VIE investments at September 30, 2016 and December 31, 2015 were as follows: (Millions) September 30, December 31, 2015 Assets: Hedge fund investments $ 34,903.8 $ 33,065.7 Private equity investments 26,352.0 28,552.5 Real estate partnerships 6,473.0 6,808.7 Total $ 67,728.8 $ 68,426.9 Liabilities: Hedge fund investments $ 4,110.0 $ 3,535.3 Private equity investments 2,527.8 3,235.7 Real estate partnerships 4,808.6 5,044.5 Total $ 11,446.4 $ 11,815.5 Non-controlling (Minority) Interests At September 30, 2016 and December 31, 2015 , continuing business non-controlling interests were $61 million and $64 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 loss attributable to non-controlling interests was $6.7 million and $3.5 million for the three and nine months ended September 30, 2016 , respectively. Net income attributable to non-controlling interests was $2.3 million and $3.9 million for the three and nine months ended September 30, 2015 , 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 and nine months ended September 30, 2016 and 2015 were as follows: Three Months Ended Nine Months Ended September 30, September 30, (Millions) 2016 2015 2016 2015 Debt securities $ 186.7 $ 196.7 $ 578.0 $ 594.4 Mortgage loans 24.1 22.6 74.2 66.2 Other investments 17.5 4.7 64.1 67.2 Gross investment income 228.3 224.0 716.3 727.8 Investment expenses (9.9 ) (10.7 ) (29.2 ) (34.2 ) Net investment income (1) $ 218.4 $ 213.3 $ 687.1 $ 693.6 (1) Net investment income includes $47.6 million and $158.3 million for the three and nine months ended September 30, 2016 , respectively, and $50.3 million and $191.7 million for the three and nine months ended September 30, 2015 , respectively, related to investments supporting our experience rated and discontinued products.

Health Care Reform

Health Care Reform	9 Months Ended
	Sep. 30, 2016
Health Care Reform [Abstract]
Health Care Reform Programs	8. Health Care Reform’s Reinsurance, Risk Adjustment and Risk Corridor (the “3Rs”) We participate in certain public health insurance exchanges (“Public Exchanges”) established pursuant to the Patient Protection and Affordable Care Act and the Health Care and Education Reconciliation Act of 2010 (as amended, collectively, “Health Care Reform” or the “ACA”). 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 a portion of the health care costs (“Cost Sharing Subsidy”) for low-income individual Public Exchange members. In addition, HHS administers the 3Rs risk management programs. Our net receivable (payable) related to the 3Rs risk management programs at September 30, 2016 and December 31, 2015 were as follows: At September 30, 2016 At December 31, 2015 (Millions) Reinsurance Risk Adjustment Risk Corridor Reinsurance Risk Adjustment Risk Corridor Current (1) $ 132.9 $ (555.1 ) $ (53.9 ) $ 394.5 $ (710.2 ) $ (8.1 ) Long-term 10.1 49.1 — — — — Total net receivable (payable) $ 143.0 $ (506.0 ) $ (53.9 ) $ 394.5 $ (710.2 ) $ (8.1 ) (1) At September 30, 2016, $41.7 million of ACA reinsurance receivables and $35.4 million of ACA risk adjustment receivables related to the respective 2015 programs. The remainder of the net balances related to the respective 2016 programs. At September 30, 2016 , we estimate that we are entitled to receive a total of $377 million from HHS under the three year ACA risk corridor program for the 2014 through 2016 program years. At September 30, 2016, we did not record any ACA risk corridor receivables related to the 2016 or 2015 program years or any amount in excess of the prorated 12.6% HHS funding amount received for the 2014 program year, because payments from HHS are uncertain. We expect to perform an annual final reconciliation and settlement with HHS of the Cost Sharing Subsidy and the 3Rs in each subsequent year.

Other Comprehensive (Loss) Inco

Other Comprehensive (Loss) Income	9 Months Ended
	Sep. 30, 2016
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive (Loss) Income	9. Other Comprehensive (Loss) Income Shareholders’ equity included the following activity in accumulated other comprehensive loss for the nine months ended September 30, 2016 and 2015 : Net Unrealized Gains (Losses) Pension and OPEB Plans Total Securities Foreign Unrecognized Net Actuarial Losses Unrecognized Prior Service Credit (Millions) Previously Impaired (1) All Other Nine months ended September 30, 2016 Balance at December 31, 2015 $ 18.7 $ 312.4 $ (74.0 ) $ (1,602.3 ) $ 14.9 $ (1,330.3 ) Other comprehensive (loss) income before reclassifications (3.4 ) 403.2 (176.1 ) — — 223.7 Amounts reclassified from accumulated other comprehensive income 4.1 (2 ) (19.5 ) (2 ) 11.3 (3 ) 31.1 (4 ) (2.0 ) (4 ) 25.0 Other comprehensive income (loss) .7 383.7 (164.8 ) 31.1 (2.0 ) 248.7 Balance at September 30, 2016 $ 19.4 $ 696.1 $ (238.8 ) $ (1,571.2 ) $ 12.9 $ (1,081.6 ) Nine months ended September 30, 2015 Balance at December 31, 2014 $ 34.9 $ 568.0 $ (60.9 ) $ (1,670.9 ) $ 17.6 $ (1,111.3 ) Other comprehensive (loss) income before reclassifications (19.7 ) (229.5 ) (36.2 ) — — (285.4 ) Amounts reclassified from accumulated other comprehensive income 6.8 (2 ) 42.2 (2 ) 2.9 (3 ) 31.3 (4 ) (2.0 ) (4 ) 81.2 Other comprehensive (loss) income (12.9 ) (187.3 ) (33.3 ) 31.3 (2.0 ) (204.2 ) Balance at September 30, 2015 $ 22.0 $ 380.7 $ (94.2 ) $ (1,639.6 ) $ 15.6 $ (1,315.5 ) (1) Represents unrealized gains or losses 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 Statements 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 Statements of Income, except for the effective portion of derivatives related to interest rate swaps which are reflected in interest expense during the nine months ended September 30, 2016 or 2015 . Refer to Note 12 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 Statements of Income. Refer to Note 11 for additional information. Refer to the Consolidated Statements of Comprehensive Income for additional information regarding reclassifications out of accumulated other comprehensive income on a pretax basis.

Financial Instruments

Financial Instruments	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Financial Instruments	10. 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 in 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 in 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 in 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. The fair values of our Level 2 debt securities are obtained 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 review these prices to ensure they are based on observable market inputs that include, but are not limited to, quoted prices for similar assets in active markets, quoted prices for identical assets in inactive markets and inputs that are observable but not prices (for example, interest rates and credit risks). We also review the methodologies and the assumptions used to calculate prices from these observable inputs. On a quarterly basis, we select a sample of our Level 2 debt securities’ prices and compare them to prices provided by a secondary source. Variances over a specified threshold are identified and reviewed to confirm the price provided by the primary source represents an appropriate estimate of fair value. In addition, our internal investment team consistently compares the prices obtained for select Level 2 debt securities to the team’s own independent estimates of fair value for those securities. We obtained one price for each of our Level 2 debt securities and did not adjust any of these prices at September 30, 2016 or December 31, 2015 . 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 September 30, 2016 or December 31, 2015 . The total fair value of our broker quoted debt securities was $112 million at September 30, 2016 and $78 million at December 31, 2015 . 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 placed. Our publicly-traded securities are classified in Level 1 because quoted prices are available for these securities in an active market. For privately-placed equity securities, there is no active market; therefore, we classify these securities in 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 in Level 1. Certain of our derivative instruments are valued using models that primarily use market observable inputs and therefore are classified in 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 September 30, 2016 and December 31, 2015 were as follows: (Millions) Level 1 Level 2 Level 3 Total September 30, 2016 Assets: Debt securities: U.S. government securities $ 1,610.5 $ 188.4 $ — $ 1,798.9 States, municipalities and political subdivisions — 5,245.8 .9 5,246.7 U.S. corporate securities — 8,712.4 75.0 8,787.4 Foreign securities — 3,199.2 30.7 3,229.9 Residential mortgage-backed securities — 860.0 — 860.0 Commercial mortgage-backed securities — 1,357.6 30.8 1,388.4 Other asset-backed securities — 1,072.3 — 1,072.3 Redeemable preferred securities — 27.1 1.8 28.9 Total debt securities 1,610.5 20,662.8 139.2 22,412.5 Equity securities 114.3 — 33.8 148.1 Derivatives — — — — Total $ 1,724.8 $ 20,662.8 $ 173.0 $ 22,560.6 Liabilities: Derivatives $ — $ .2 $ — $ .2 December 31, 2015 Assets: Debt securities: U.S. government securities $ 1,671.0 $ 200.7 $ — $ 1,871.7 States, municipalities and political subdivisions — 5,123.4 1.1 5,124.5 U.S. corporate securities — 8,110.5 63.9 8,174.4 Foreign securities — 2,972.3 24.8 2,997.1 Residential mortgage-backed securities — 924.9 — 924.9 Commercial mortgage-backed securities — 1,270.6 — 1,270.6 Other asset-backed securities — 894.3 — 894.3 Redeemable preferred securities — 39.0 5.5 44.5 Total debt securities 1,671.0 19,535.7 95.3 21,302.0 Equity securities 1.7 — 19.3 21.0 Derivatives — 19.7 — 19.7 Total $ 1,672.7 $ 19,555.4 $ 114.6 $ 21,342.7 Liabilities: Derivatives $ — $ 88.3 $ — $ 88.3 There were no transfers between Levels 1 and 2 during the three or nine months ended September 30, 2016 or 2015 . During both the three and nine months ended September 30, 2016 we had an immaterial amount of gross transfers out of Level 3 financial assets. During the three and nine months ended September 30, 2015 , we had gross transfers out of Level 3 of $29 million and $62 million , respectively, related to other asset-backed securities. During both the three and nine months ended September 30, 2016 and 2015 , we had an immaterial amount of gross transfers into Level 3 financial assets. 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 creditworthiness 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 in Level 2. For bank loans classified in 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. Equity securities: Certain of our equity securities are carried at cost. The fair values of our cost-method investments are not estimated if there are no identified events or changes in circumstances that may have a significant adverse effect on the fair value of the investment. 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 our financial instruments carried at adjusted cost or contract value at September 30, 2016 and December 31, 2015 were as follows: Carrying Value Estimated Fair Value (Millions) Level 1 Level 2 Level 3 Total September 30, 2016 Assets: Mortgage loans $ 1,518.5 $ — $ — $ 1,575.7 $ 1,575.7 Bank loans 8.7 — — 8.1 8.1 Equity securities (1) 35.2 N/A N/A N/A N/A Liabilities: Investment contract liabilities: With a fixed maturity 8.7 — — 8.7 8.7 Without a fixed maturity 381.9 — — 381.8 381.8 Long-term debt 20,662.2 — 22,091.8 — 22,091.8 December 31, 2015 Assets: Mortgage loans $ 1,553.7 $ — $ — $ 1,598.7 $ 1,598.7 Bank loans 192.8 — 179.9 7.6 187.5 Equity securities (1) 34.9 N/A N/A N/A N/A Liabilities: Investment contract liabilities: With a fixed maturity 8.6 — — 8.6 8.6 Without a fixed maturity 371.3 — — 351.1 351.1 Long-term debt 7,785.4 — 8,227.3 — 8,227.3 (1) It was not practical to estimate the fair value of these cost-method investments as it represents shares of unlisted companies. 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 in this Note 10 . 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 in 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 September 30, 2016 and December 31, 2015 were as follows: September 30, 2016 December 31, 2015 (Millions) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Debt securities $ 844.9 $ 2,460.5 $ 3.2 $ 3,308.6 $ 750.4 $ 2,382.0 $ 3.8 $ 3,136.2 Equity securities 167.3 5.5 — 172.8 169.8 5.2 — 175.0 Derivatives — — — — — .2 — .2 Common/collective trusts — 610.6 — 610.6 — 540.2 — 540.2 Total (1) $ 1,012.2 $ 3,076.6 $ 3.2 $ 4,092.0 $ 920.2 $ 2,927.6 $ 3.8 $ 3,851.6 (1) Excludes $225.7 million and $183.5 million of cash and cash equivalents and other receivables at September 30, 2016 and December 31, 2015 , respectively. During the three and nine months ended September 30, 2016 and 2015 , we had an immaterial amount of Level 3 Separate Accounts financial assets. 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 at September 30, 2016 and December 31, 2015 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 September 30, 2016 Derivatives $ — $ 14.1 $ — $ 14.1 Total $ — $ 14.1 $ — $ 14.1 December 31, 2015 Derivatives $ 19.7 $ 11.8 $ (16.4 ) $ 15.1 Total $ 19.7 $ 11.8 $ (16.4 ) $ 15.1 (1) There were no amounts offset in our balance sheets at September 30, 2016 or December 31, 2015 . Financial liabilities, including derivative liabilities, subject to offsetting and enforceable master netting arrangements at September 30, 2016 and December 31, 2015 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 September 30, 2016 Derivatives $ .2 $ — $ — $ .2 Total $ .2 $ — $ — $ .2 December 31, 2015 Derivatives $ 88.3 $ — $ (90.7 ) $ (2.4 ) Total $ 88.3 $ — $ (90.7 ) $ (2.4 ) (1) There were no amounts offset in our balance sheets at September 30, 2016 or December 31, 2015 .

Pension and Other Postretiremen

Pension and Other Postretirement Plans	9 Months Ended
	Sep. 30, 2016
Compensation and Retirement Disclosure [Abstract]
Pension and Other Postretirement Plans	11. 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 and nine months ended September 30, 2016 and 2015 were as follows: Pension Plans OPEB Plans Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, (Millions) 2016 2015 2016 2015 2016 2015 2016 2015 Amortization of prior service credit $ (.1 ) $ (.1 ) $ (.3 ) $ (.3 ) $ (.8 ) $ (1.0 ) $ (2.7 ) $ (2.8 ) Interest cost 64.9 65.3 194.8 195.7 2.7 2.7 8.1 8.1 Expected return on plan assets (97.3 ) (104.8 ) (291.9 ) (314.3 ) (.7 ) (.7 ) (1.9 ) (2.2 ) Recognized net actuarial losses 15.4 15.3 46.1 46.1 .6 .7 1.8 2.0 Net periodic benefit (income) cost $ (17.1 ) $ (24.3 ) $ (51.3 ) $ (72.8 ) $ 1.8 $ 1.7 $ 5.3 $ 5.1 We do not expect to make a voluntary cash contribution to our tax-qualified noncontributory defined benefit pension plan in 2016. In September 2016, we announced a voluntary early retirement program (the “Program”). Under the terms of the Program, eligible employees can elect early retirement during the month of October. We expect to record an expense associated with the Program in the fourth quarter of 2016.

Debt

Debt	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Debt	12. Debt The carrying value of our long-term debt at September 30, 2016 and December 31, 2015 was as follows: (Millions) September 30, December 31, Senior notes, 5.95%, due March 2017 (1) $ 390.5 $ 402.4 Senior notes, 1.75%, due May 2017 (1) 249.6 249.1 Senior notes, 1.5%, due November 2017 498.6 497.7 Senior notes, floating rate, due December 2017 498.9 — Senior notes, 1.7%, due June 2018 996.6 — Senior notes, 2.2%, due March 2019 373.4 372.9 Senior notes, 1.9%, due June 2019 1,641.2 — Senior notes, 3.95%, due September 2020 744.4 743.4 Senior notes, 2.4%, due June 2021 1,838.3 — Senior notes, 5.45%, due June 2021 664.6 674.9 Senior notes, 4.125%, due June 2021 494.9 494.1 Senior notes, 2.75%, due November 2022 985.0 983.1 Senior notes, 2.8%, due June 2023 1,289.6 — Senior notes, 3.5%, due November 2024 742.3 741.6 Senior notes, 3.2%, due June 2026 2,770.4 — Senior notes, 4.25%, due June 2036 1,480.0 — Senior notes, 6.625%, due June 2036 765.1 765.0 Senior notes, 6.75%, due December 2037 527.3 527.0 Senior notes, 4.5%, due May 2042 477.7 477.1 Senior notes, 4.125%, due November 2042 489.0 488.6 Senior notes, 4.75%, due March 2044 370.6 370.5 Senior notes, 4.375%, due June 2046 2,375.3 — Total long-term debt 20,663.3 7,787.4 Less current portion of long-term debt 640.1 — Less credit facility issuance costs 1.1 2.0 Total long-term debt, less current portion and credit facility issuance costs $ 20,022.1 $ 7,785.4 (1) At September 30, 2016 , our 5.95% senior notes due March 2017 and 1.75% senior notes due May 2017 are each classified as current in our consolidated balance sheet. Humana-Related Senior Notes; Long-Term Debt and Bridge Credit Agreement In June 2016, in connection with the Humana Acquisition, we issued the Humana-related senior notes, which are comprised of: $500 million of floating rate senior notes due December 2017, $1.0 billion of 1.7% senior notes due June 2018, approximately $1.7 billion of 1.9% senior notes due June 2019, approximately $1.9 billion of 2.4% senior notes due June 2021, $1.3 billion of 2.8% senior notes due June 2023, $2.8 billion of 3.2% senior notes due June 2026, $1.5 billion of 4.25% senior notes due June 2036 and $2.4 billion of 4.375% senior notes due June 2046. If the Humana Acquisition has not been completed by December 31, 2016 (or such later date to which the “End Date” under the Merger Agreement is extended by agreement between us and Humana) or if, prior to such date, the Merger Agreement is terminated, we must redeem the entire $10.2 billion aggregate principal amount of the 2016 Humana-related senior notes that are due in 2019, 2021, 2026, 2036 and 2046 at a redemption price equal to 101% of the aggregate principal amount of those notes plus accrued and unpaid interest. On July 30, 2015, we entered into a $13.0 billion 364-day senior unsecured bridge credit agreement (the “Bridge Credit Agreement”) with a group of fifteen lenders. In connection with the closing of the 2016 Humana-related senior notes, we terminated the Bridge Credit Agreement effective June 9, 2016. There were no amounts outstanding under the Bridge Credit Agreement at any time during the nine months ended September 30, 2016 . Cash Flow Hedges From September 2015 through June 2016, prior to issuing the 2016 Humana-related senior notes, we entered into various interest rate swaps and treasury rate locks with an aggregate notional value of $3.5 billion . We designated these interest rate swaps and treasury rate locks as cash flow hedges against interest rate exposure related to the forecasted future issuance of fixed-rate debt to be primarily used to finance a portion of the purchase price of the Humana Acquisition. During the second quarter of 2016, prior to issuing the 2016 Humana-related senior notes, we terminated interest rate swaps with an aggregate notional value of $2.3 billion and paid an aggregate of $193 million to the swap counterparties upon termination. We performed a final effectiveness test upon the termination of each swap, and the effective portion of the hedge loss of $193 million was recorded in accumulated other comprehensive loss, net of tax, as the forecasted future issuance of fixed-rate debt associated with the Humana Acquisition remained probable of occurring at the time of termination. The hedge loss is being amortized as an increase to interest expense over a period consistent with the term of the hedged 2016 Humana-related senior notes. Upon termination of the interest rate swaps, we concurrently entered into treasury rate locks with an aggregate notional value of $2.3 billion to replace the vacated hedged positions. The treasury rate locks were designated as cash flow hedges against interest rate exposure related to the forecasted future issuance of fixed-rate debt to be primarily used to finance a portion of the purchase price of the Humana Acquisition. In June 2016, in conjunction with the issuance of the 2016 Humana-related senior notes, we terminated outstanding interest rate swaps and treasury rate locks with an aggregate notional value of $3.5 billion and paid an aggregate of $51 million to the hedge counterparties upon termination. We performed a final effectiveness test upon termination of each interest rate swap and treasury rate lock, and the effective portion of the hedge loss of $51 million was recorded in accumulated other comprehensive loss, net of tax, and is being amortized as an increase to interest expense over a period consistent with the term of the hedged 2016 Humana-related senior notes. 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. On September 30, 2015, we modified the timing of the forecasted future issuance of fixed-rate debt in conjunction with the expected timing of the financing of the Humana Acquisition and, as a result, we de-designated these swaps and re-designated them as cash flow hedges against interest rate exposure related to the forecasted future issuance of fixed-rate debt. The effective portion of the hedge loss of $73 million pretax remains in accumulated other comprehensive loss, net of tax, and will be amortized as an increase to interest expense over the first 20 semi-annual interest payments related to the fixed-rate debt. At March 31, 2016, we performed a quarterly effectiveness test of these swaps and determined there was $4 million pretax of ineffectiveness. That ineffectiveness was recorded as a realized capital loss in the first quarter of 2016. In June 2016, we terminated the hedges in conjunction with the issuance of the 2016 Humana-related senior notes and paid an aggregate of $103 million to the hedge counterparties upon termination of the interest rate swaps. We performed a final effectiveness test upon termination of each interest rate swap and determined there was $2 million pretax of ineffectiveness. That ineffectiveness was recorded as a realized capital loss in the second quarter of 2016. The effective portion of the hedge loss of $25 million pretax was recorded in accumulated other comprehensive loss, net of tax, and is being amortized as an increase to interest expense over the first 20 semi-annual interest payments of certain of the hedged 2016 Humana-related senior notes. Refer to Note 9 for additional information regarding hedge losses reclassified from accumulated other comprehensive loss to net income during the nine months ended September 30, 2016 . At September 30, 2016 , the total amount of amortization over the next twelve months for our cash flow hedges will increase interest expense by $30 million . If we are required to redeem certain of the 2016 Humana-related senior notes as described above, the entire unrealized hedge loss recorded in accumulated other comprehensive loss related to the redeemed notes will be recognized in net income upon such redemption. 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, and in connection with the acquisition of Coventry Health Care, Inc. (“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 Agreement”). On March 2, 2015, we entered into a Second Amendment to the Credit Agreement (the “Second Amendment”). On July 30, 2015, in connection with the Humana Acquisition, we entered into a Third Amendment (the “Third Amendment,” and together with the First Amendment, the Incremental Commitment Agreement, the Second Amendment and the Credit Agreement, resulting in the “Facility”). The Facility is an unsecured $2.0 billion revolving credit agreement. The Third Amendment permits us to increase the commitments available under the Facility from $2.0 billion to $3.0 billion upon our request and the satisfaction of certain conditions, including the completion of the transactions contemplated by the Merger Agreement and the termination of Humana’s existing credit agreement dated as of July 9, 2013 (“Humana’s Existing Credit Agreement”). The Third Amendment also modified the calculation of total debt for purposes of determining compliance prior to the closing date of the Humana Acquisition (the “Closing Date”) with certain covenants to exclude debt incurred by us to finance the Humana Acquisition, the other financing transactions related to the Humana Acquisition and/or the payment of fees and expenses incurred in connection therewith so long as either (A) the net proceeds of such debt are set aside to finance the Humana Acquisition, the other financing transactions related to the Humana Acquisition and/or the payment of fees and expenses incurred in connection therewith or (B) such debt is subject to mandatory redemption in the event that the Merger Agreement is terminated or expires. In addition, upon our agreement with one or more financial institutions, we may expand the commitments under the Facility by an additional $500 million . 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 each of 2013, 2014 and 2015 we extended the maturity date of the Facility by one year. The maturity date of the Facility is March 27, 2020. 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 .050% to .150% per annum, depending upon our long-term senior unsecured debt rating. The facility fee was .100% at September 30, 2016 . 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 September 30, 2016 . There were no amounts outstanding under the Facility at any time during the nine months ended September 30, 2016 or 2015. Term Loan Agreement On July 30, 2015, we entered into a senior three-year term loan credit agreement (the “Term Loan Agreement”) with a group of seventeen lenders. Under the Term Loan Agreement, on or before December 31, 2016, we may borrow on an unsecured basis an aggregate principal amount of up to $3.2 billion . Any proceeds of the Term Loan Agreement are required to be used to fund the Humana Acquisition and to pay fees and expenses in connection with the Humana Acquisition. The lenders’ obligation to fund the loans under the Term Loan Agreement is subject to the satisfaction of certain conditions, including the completion of the transactions contemplated by the Merger Agreement and the termination of Humana’s Existing Credit Agreement. Any borrowings under the Term Loan Agreement mature three years after the Closing Date. The Term Loan Agreement 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 Term Loan Agreement). For purposes of determining compliance prior to the Closing Date with certain covenants, total debt also excludes debt incurred by us to finance the Humana Acquisition, the other financing transactions related to the Humana Acquisition and/or the payment of fees and expenses incurred in connection therewith so long as either (A) the net proceeds of such debt are set aside to finance the Humana Acquisition, the other financing transactions related to the Humana Acquisition and/or the payment of fees and expenses incurred in connection therewith or (B) such debt is subject to mandatory redemption in the event that the Merger Agreement is terminated or expires. The Term Loan Agreement also contains a covenant limiting “Restricted Payments” (as defined in the Term Loan Agreement) by Aetna, subject to certain exceptions and baskets, including an exception permitting the payment of regular cash dividends. We met these requirements at September 30, 2016 . Amounts outstanding under the Term Loan Agreement will bear interest, at our option, either (a) at LIBOR; or (b) at the base rate (defined as the highest of (i) the prime rate, (ii) the federal funds effective rate plus 0.50% per annum and (iii) LIBOR for an interest period of one month plus 1.00% per annum), plus, in each case, the applicable LIBOR margin or base rate margin depending upon the ratings of our long-term senior unsecured debt. The minimum and maximum LIBOR margins are 0.75% and 1.50% per annum, respectively, and the minimum and maximum base rate margins are 0.0% and 0.50% per annum, respectively. We will also pay the lenders certain other fees. There were no amounts outstanding under the Term Loan Agreement at any time during the nine months ended September 30, 2016 . Federal Home Loan Bank of Boston We are a member of the Federal Home Loan Bank of Boston (the “FHLBB”), and as a member we have the ability to obtain cash advances, subject to certain minimum collateral requirements. Our maximum borrowing capacity available from the FHLBB at September 30, 2016 was $902 million . At both September 30, 2016 and December 31, 2015 , we did not have any outstanding borrowings from the FHLBB.

Capital Stock

Capital Stock	9 Months Ended
	Sep. 30, 2016
Class of Stock Disclosures [Abstract]
Capital Stock	13. Capital Stock On November 21, 2014 and February 28, 2014, our Board of Directors (our “Board”) authorized two separate share repurchase programs of our common stock of up to $1.0 billion each. We did not repurchase any shares of common stock during the nine months ended September 30, 2016 . At September 30, 2016 , we had remaining authorization to repurchase an aggregate of up to approximately $1.1 billion of common stock under the November 21, 2014 and February 28, 2014 programs. The repurchases are effected from time to time in the open market, through negotiated transactions, including accelerated share repurchase agreements, and through plans designed to comply with Rule 10b5-1 under the Securities Exchange Act of 1934, as amended. During the nine months ended September 30, 2016 our Board declared the following cash dividends: Date Declared Dividend Amount Per Share Stockholders of Record Date Date Paid/ To be Paid Total Dividends (Millions) February 19, 2016 $ .25 April 14, 2016 April 29, 2016 $ 87.6 May 20, 2016 .25 July 14, 2016 July 29, 2016 87.7 September 30, 2016 .25 October 13, 2016 October 28, 2016 87.7 Prior to completion of the Humana Acquisition, pursuant to the Merger Agreement, our regular quarterly cash dividend will not exceed $.25 per share. Our dividend policy following the completion of the Humana Acquisition will be determined by our Board. 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 February 19, 2016, .3 million PSUs, .9 million restricted stock units (“RSUs”) and 2.2 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 certain operating performance goals, as determined by our Board’s Committee on Compensation and Talent Management, during a three-year performance period which began January 1, 2016 and ends on December 31, 2018. The vesting period for the PSUs ends on February 19, 2019. Each vested PSU 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 $103.45 per share, the closing price of our common stock on the grant date. SARs will generally become 100% vested approximately three years from the grant date, with one-third vesting on each anniversary of the grant date. The SARs granted to certain employees during first quarters of 2016 and 2015 had an estimated fair market value of $34.33 and $32.13 per unit, respectively. The fair value per unit was calculated on each respective grant date using a modified Black-Scholes option pricing model using the following assumptions during the first quarters of 2016 and 2015 : 2016 2015 Expected term (in years) 7.11 6.48 Volatility 32.9 % 33.4 % Risk-free interest rate 1.52 % 1.81 % Dividend yield .91 % 1.13 % Initial price $ 103.45 $ 100.50 The expected term is based on historical equity award activity. 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 7-year and 10-year U.S. Treasury rates for 2016 SARs grants and the 5-year and 10-year U.S. Treasury rates for 2015 SARs grants. The dividend yield is based on our historical dividends in the 12 months prior to the grant date. There were no material SARs granted during the three months ended September 30, 2016 or 2015 .

Dividend Restrictions and Statu

Dividend Restrictions and Statutory Surplus	9 Months Ended
	Sep. 30, 2016
Dividend Restrictions and Statutory Surplus [Abstract]
Dividend Restrictions and Statutory Surplus	14. Dividend Restrictions and Statutory Surplus Under applicable regulatory requirements at September 30, 2016 , the amount of dividends that may be paid through the end of 2016 by our insurance and HMO subsidiaries without prior approval by regulatory authorities was $396 million in the aggregate. There are no such regulatory restrictions on distributions from Aetna to its shareholders. Prior to completion of the Humana Acquisition, pursuant to the Merger Agreement, Aetna is not permitted to declare, set aside or pay any dividend or other distribution other than a regular quarterly cash dividend in the ordinary course of business, which will not exceed $.25 per share. In addition, the Term Loan Agreement contains a covenant limiting “Restricted Payments” (as defined in the applicable agreement) by Aetna, subject to certain exceptions and baskets, including an exception permitting the payment of regular cash dividends. During the third quarter of 2016 , our insurance and HMO subsidiaries paid $320 million of dividends to the Company. The aggregate statutory capital and surplus of our insurance and HMO subsidiaries was $10.1 billion and $9.9 billion at September 30, 2016 and December 31, 2015 , respectively.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	15. Commitments and Contingencies Guaranty Fund Assessments, Market Stabilization and Other Non-Voluntary Risk Sharing Pools Under guaranty fund laws existing in all states, insurers doing business in those states can be assessed (up to prescribed limits) for certain obligations of insolvent insurance companies to policyholders and claimants. The life and health insurance guaranty associations in which we participate that operate under these laws respond to insolvencies of long-term care insurers as well as health insurers. Our assessments generally are based on a formula relating to our premiums in the state compared to the premiums of other insurers. Certain states allow assessments to be recovered as offsets to premium taxes. Some states have similar laws relating to HMOs and/or other payors such as not-for-profit consumer-governed health plans established under the ACA. In 2009, the Pennsylvania Insurance Commissioner (the “Commissioner”) placed long-term care insurer Penn Treaty Network America Insurance Company and one of its subsidiaries (collectively, “Penn Treaty”) in rehabilitation, an intermediate action before insolvency, and subsequently petitioned a state court to convert the rehabilitation into a liquidation. In 2012, the state court denied the Commissioner’s petition for liquidation. The Pennsylvania Supreme Court affirmed that ruling in July 2015. Between April 2013 and October 2014, the Commissioner filed proposed rehabilitation plans, which have been withdrawn. In July 2016, the Commissioner again petitioned the state court to convert the rehabilitation into a liquidation. A hearing to consider that petition is scheduled for November 9, 2016. If Penn Treaty is placed in liquidation, we and other insurers likely would be assessed immediately or over a period of years by guaranty associations for the payments the guaranty associations are required to make to Penn Treaty policyholders. We are currently unable to predict the ultimate outcome of, or reasonably estimate the loss or range of losses resulting from, this potential insolvency because we cannot predict when or to what extent Penn Treaty ultimately will be declared insolvent, the amount of the insolvency, the amount and timing of associated future guaranty association assessments or the amount or availability of potential offsets, such as premium tax offsets. It is reasonably possible that during 2016 we may record a liability and expense relating to Penn Treaty and/or other insolvencies which could have a material adverse effect on our operating results, financial position and cash flows. While we have historically recovered more than half of guaranty fund assessments through statutorily permitted premium tax offsets, significant increases in assessments could lead to legislative and/or regulatory actions that may limit future offsets. HMOs in certain states in which we do business are subject to assessments, including market stabilization and other risk-sharing pools, for which we are assessed charges based on incurred claims, demographic membership mix and other factors. We establish liabilities for these assessments based on applicable laws and regulations. In certain states, the ultimate assessments we pay are dependent upon our experience relative to other entities subject to the assessment, and the ultimate liability is not known at the balance sheet date. While the ultimate amount of the assessment is dependent upon the experience of all pool participants, we believe we have adequate reserves to cover such assessments. Humana Acquisition Related Matters If the Humana Acquisition has not been completed by December 31, 2016 (or such later date to which the “End Date” under the Merger Agreement is extended by agreement between us and Humana) or if, prior to such date, the Merger Agreement is terminated, we must redeem $10.2 billion aggregate principal amount of the 2016 Humana-related senior notes that are due in 2019, 2021, 2026, 2036 and 2046 at a redemption price equal to 101% of the aggregate principal amount of those notes plus accrued and unpaid interest and recognize the entire unamortized portion of the related cash flow hedge losses, debt issuance costs and debt issuance discounts in our net income upon such redemption. For additional information on the 2016 Humana-related senior notes, refer to Notes 3 , 6 and 12 . We may be required to pay Humana a regulatory termination fee of $1 billion if the Merger Agreement is terminated under certain circumstances. Litigation and Regulatory Proceedings Humana Acquisition - Department of Justice Litigation On July 21, 2016, the DOJ and certain state attorneys general filed a civil complaint in the U.S. District Court for the District of Columbia against us and Humana charging that the Humana Acquisition would violate Section 7 of the Clayton Antitrust Act, and seeking a permanent injunction to prevent Aetna from acquiring Humana. The trial in the DOJ litigation is scheduled to begin during December 2016, and the trial court decision in the DOJ litigation is expected in January 2017. We plan to vigorously defend the Humana Acquisition. 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 (“RICO”) 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 $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. 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 million ( $103 million pretax). On June 30, 2015, the New Jersey District Court granted in part our motion to dismiss the proceeding. The New Jersey District Court dismissed with prejudice the plaintiffs’ RICO and federal antitrust claims; their ERISA claims that are based on our disclosures and our purported breach of fiduciary duties; and certain of their state law claims. The New Jersey District Court also dismissed with prejudice all claims asserted by several medical association plaintiffs. The plaintiffs’ remaining claims are for ERISA benefits and breach of contract. We intend to vigorously defend ourselves against the plaintiffs’ remaining claims. 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, and we are involved in other litigation regarding, 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 prepared, 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 to us and document their medical records, including the diagnosis data submitted to us with claims. 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, to validate coding practices and supporting medical record documentation maintained by health care providers and the resulting risk adjusted premium payments to the plans. CMS may require us to refund premium payments if our risk adjusted premiums are not properly supported by medical record data. 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 revised its audit methodology for RADV audits to determine refunds payable by Medicare Advantage plans for contract year 2011 and forward. Under the revised 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 revised methodology may increase our exposure to premium refunds to CMS based on incomplete medical records maintained by providers. Since 2013, CMS has selected certain of our Medicare Advantage contracts for contract years 2011 and 2012 for RADV 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, Public Exchange related or other audits by CMS, the OIG, HHS or otherwise, including audits of our minimum medical loss ratio rebates, methodology and/or reports, 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, anticompetitive practices, 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 and for government customers in our Commercial 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, the U.S. Department of the Treasury, the U.S. Food and Drug Administration, 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 our withdrawal from certain states’ Public Exchanges for 2017, 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.” A significant number of states are investigating life insurers’ claims payment and related escheat practices. 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 judicial, legislative 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 a heightened level of review and/or audit 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 provider network adequacy, the use of performance-based networks and termination of provider contracts), provider directory accuracy, calculation of minimum medical loss ratios and/or payment of related rebates, delegated arrangements, rescission of insurance coverage, limited benefit health products, student health products, pharmacy benefit management practices (including the use of narrow networks and the placement of drugs in formulary tiers), sales practices, customer service practices, vendor oversight 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, withholding of premium payments to us by government agencies, assessments of damages, civil or criminal fines or penalties, or other sanctions, including the possible suspension or loss of licensure and/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, involve claims for injunctive relief, 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	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Segment Information	16. Segment Information Our operations are conducted in three business segments: Health Care, Group Insurance and Large Case Pensions. 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 segment operations for the three and nine months ended September 30, 2016 and 2015 were as follows: (Millions) Health Care Group Insurance Large Case Pensions Corporate Financing Total Company Three Months Ended September 30, 2016 Revenue from external customers $ 14,949.9 $ 563.7 $ 14.7 $ — $ 15,528.3 Operating earnings (loss) (1) 752.5 19.1 5.0 (42.3 ) 734.3 Three Months Ended September 30, 2015 Revenue from external customers $ 14,202.3 $ 557.5 $ 13.0 $ — $ 14,772.8 Operating earnings (loss) (1) 675.4 25.6 4.4 (36.8 ) 668.6 Nine Months Ended September 30, 2016 Revenue from external customers $ 44,932.6 $ 1,683.1 $ 38.9 $ — $ 46,654.6 Operating earnings (loss) (1) 2,365.8 90.3 9.1 (126.5 ) 2,338.7 Nine Months Ended September 30, 2015 Revenue from external customers (2) $ 42,904.9 $ 1,677.6 $ 34.9 $ — $ 44,617.4 Operating earnings (loss) (1) 2,219.0 114.3 12.7 (111.0 ) 2,235.0 (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. (2) In the nine months ended September 30, 2015, we received proceeds of $71.3 million ( $109.6 million pretax), net of legal costs, in connection with a litigation settlement. These net proceeds were recorded in fees and other revenue in our GAAP Consolidated Statements of Income. A reconciliation of net income attributable to Aetna to operating earnings (1) for the three and nine months ended September 30, 2016 and 2015 was as follows: Three Months Ended Nine Months Ended September 30, September 30, (Millions) 2016 2015 2016 2015 Net income attributable to Aetna (GAAP measure) $ 603.9 $ 560.1 $ 2,131.6 $ 2,069.4 Transaction and integration-related costs 164.0 62.3 333.1 138.6 Reduction of reserve for anticipated future losses on discontinued products — — (128.5 ) — Litigation-related proceeds — — — (109.6 ) Amortization of other acquired intangible assets 61.4 65.1 187.0 192.0 Net realized capital (gains) losses (34.8 ) 33.1 (85.5 ) 23.0 Income tax benefit (60.2 ) (52.0 ) (99.0 ) (78.4 ) Operating earnings (1) $ 734.3 $ 668.6 $ 2,338.7 $ 2,235.0 (1) In addition to net realized capital losses and gains 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 during the three and nine months ended September 30, 2016 and 2015 related to the acquisitions of Coventry and bswift LLC (“bswift”) and the Humana Acquisition. 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, as well as the cost of the Bridge Credit Agreement and the Term Loan Agreement executed in connection with the Humana Acquisition, which are reflected in our GAAP Consolidated Statements of Income in interest expense. Transaction costs also include the negative cost of carry associated with the 2016 Humana-related senior notes. Prior to the closing of the Humana Acquisition, the negative cost of carry associated with the 2016 Humana-related senior notes is excluded from operating earnings. The components of the negative cost of carry are reflected in our GAAP Consolidated Statements of Income in interest expense and net investment income. On and after the closing of the Humana Acquisition, the interest expense and net investment income associated with the 2016 Humana-related senior notes no longer will be excluded from operating earnings. • In 1993, we discontinued the sale of our fully guaranteed large case pensions products and established a reserve for anticipated future losses on these products, which we review quarterly. During the nine months ended September 30, 2016, we reduced the reserve for anticipated future losses on discontinued products. We believe excluding any changes in the reserve for anticipated future losses on discontinued products from operating earnings provides more useful information as to our continuing products and is consistent with the treatment of the operating results of these discontinued products, which are credited or charged to the reserve and do not affect our operating results. Refer to Note 18 for additional information on the reduction of the reserve for anticipated future losses on discontinued products. • In the nine months ended September 30, 2015, we received proceeds, net of legal costs, in connection with a litigation settlement. These net proceeds were recorded in fees and other revenue in our GAAP Consolidated Statements of Income. • The corresponding tax benefit or expense related to the items excluded from operating earnings discussed above. The tax benefit or expense was calculated utilizing the appropriate tax rate for each individual item excluded from operating earnings.

Reinsurance

Reinsurance	9 Months Ended
	Sep. 30, 2016
Reinsurance Disclosures [Abstract]
Reinsurance	17. Reinsurance In January 2016, we entered into four-year reinsurance agreements with Vitality Re VII Limited, an unrelated reinsurer. The agreements allow us to reduce our required capital and provide $200 million of collateralized excess of loss reinsurance coverage on a portion of our group Commercial Insured Health Care business.

Discontinued Products

Discontinued Products	9 Months Ended
	Sep. 30, 2016
Discontinued Products [Abstract]
Discontinued Products	18. 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. At both September 30, 2016 and December 31, 2015 , our remaining GIC liability was not material. 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. 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 2014, we modified the mortality tables used in order to reflect the more up-to-date 2014 Retired Pensioner’s Mortality table. The mortality tables were previously modified in 2012, in order to reflect the more up-to-date 2000 Retired Pensioner’s Mortality table, and in 1995, in order to reflect the 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. As a result of this review, we released $84 million ( $129 million pretax) of the reserve in the nine months ended September 30, 2016 . This reserve release was primarily due to favorable retirement experience as well as favorable investment performance compared to assumptions we previously made in estimating the reserve. The reserve at each of September 30, 2016 and December 31, 2015 reflects management’s best estimate of anticipated future losses, and is included in future policy benefits on our balance sheets. The activity in the reserve for anticipated future losses on discontinued products for the nine months ended September 30, 2016 and 2015 was as follows (pretax): (Millions) 2016 2015 Reserve, beginning of period $ 1,067.2 $ 1,014.7 Operating loss (19.9 ) (2.1 ) Net realized capital gains 49.5 57.2 Reserve reduction (128.5 ) — Reserve, end of period $ 968.3 $ 1,069.8 During the nine months ended September 30, 2016 , our discontinued products reflected operating losses and net realized capital gains, primarily attributable to gains from the sale of debt securities. During the nine months ended September 30, 2015 , our discontinued products reflected operating losses and net realized capital gains, primarily attributable to gains from the sale of other invested assets, debt securities and investment real estate. Assets and liabilities supporting discontinued products (1) at September 30, 2016 and December 31, 2015 were as follows: (Millions) 2016 2015 Assets: Debt and equity securities available for sale $ 2,082.5 $ 2,019.6 Mortgage loans 378.5 396.0 Other investments 658.1 643.5 Total investments 3,119.1 3,059.1 Other assets 87.1 128.9 Current and deferred income taxes — 20.5 Receivable from continuing products (2) 545.2 602.0 Total assets $ 3,751.4 $ 3,810.5 Liabilities: Future policy benefits $ 2,373.0 $ 2,493.5 Reserve for anticipated future losses on discontinued products 968.3 1,067.2 Current and deferred income taxes 43.1 — Other liabilities (3) 367.0 249.8 Total liabilities $ 3,751.4 $ 3,810.5 (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 $85 million and $265 million for the three and nine months ended September 30, 2016 , respectively, and $89 million and $269 million for the three and nine months ended September 30, 2015 , respectively. Participant-directed withdrawals from our discontinued products were not significant during the three or nine months ended September 30, 2016 or 2015 . Cash required to fund these distributions was provided by earnings and scheduled payments on, and sales of, invested assets.

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2016
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 2015 Annual Report on Form 10-K (our “2015 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 2015 Annual Report, unless the information contained in those disclosures materially changed and is required by GAAP. The Company has evaluated subsequent events that occurred after September 30, 2016 through the date the financial statements were issued and determined there were no subsequent events to disclose.
Reclassifications	Reclassifications Certain reclassifications were made to 2015 financial information to conform with the 2016 presentation.
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.

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Earnings Per Share	The computations of basic and diluted EPS for the three and nine months ended September 30, 2016 and 2015 are as follows: Three Months Ended Nine Months Ended September 30, September 30, (Millions, except per common share data) 2016 2015 2016 2015 Net income attributable to Aetna $ 603.9 $ 560.1 $ 2,131.6 $ 2,069.4 Weighted average shares used to compute basic EPS 351.4 349.2 351.1 349.2 Dilutive effect of outstanding stock-based compensation awards 2.9 3.3 3.0 3.3 Weighted average shares used to compute diluted EPS 354.3 352.5 354.1 352.5 Basic EPS $ 1.72 $ 1.60 $ 6.07 $ 5.93 Diluted EPS $ 1.70 $ 1.59 $ 6.02 $ 5.87
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 and nine months ended September 30, 2016 and 2015 are as follows: Three Months Ended Nine Months Ended September 30, September 30, (Millions) 2016 2015 2016 2015 Stock appreciation rights (“SARs”) (1) — .1 .1 .7 Other stock-based compensation awards (2) .7 .5 .8 .8 (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) Performance stock units ("PSUs"), certain market stock units ("MSUs") with performance conditions, and performance stock appreciation rights ("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)	9 Months Ended
	Sep. 30, 2016
Operating Expenses [Abstract]
Operating Expenses	For the three and nine months ended September 30, 2016 and 2015 , 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: Three Months Ended Nine Months Ended September 30, September 30, (Millions) 2016 2015 2016 2015 Selling expenses $ 408.6 $ 393.0 $ 1,245.4 $ 1,213.6 General and administrative expenses: Salaries and related benefits 1,258.1 1,242.3 3,737.2 3,665.3 Other general and administrative expenses (1) 1,164.0 1,193.8 3,494.8 3,566.2 Total general and administrative expenses 2,422.1 2,436.1 7,232.0 7,231.5 Total operating expenses $ 2,830.7 $ 2,829.1 $ 8,477.4 $ 8,445.1 (1) The three and nine months ended September 30, 2016 include estimated fees mandated by the ACA (as defined in Note 8 ) comprised primarily of the health insurer fee of $210.6 million and $627.6 million , respectively, and our estimated contribution to the funding of the ACA’s reinsurance program of $29.6 million and $88.6 million , respectively. The three and nine months ended September 30, 2015 include estimated fees mandated by the ACA comprised primarily of the health insurer fee of $209.7 million and $642.2 million , respectively, and our estimated contribution to the funding of the ACA’s reinsurance program of $51.6 million and $157.4 million , respectively.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2016
Investments [Abstract]
Total investments	Total investments at September 30, 2016 and December 31, 2015 were as follows: September 30, 2016 December 31, 2015 (Millions) Current Long-term Total Current Long-term Total Debt and equity securities available for sale $ 2,813.8 $ 19,746.8 $ 22,560.6 $ 2,877.1 $ 18,445.9 $ 21,323.0 Mortgage loans 168.4 1,350.1 1,518.5 126.9 1,426.8 1,553.7 Other investments — 1,659.2 1,659.2 10.8 1,792.1 1,802.9 Total investments $ 2,982.2 $ 22,756.1 $ 25,738.3 $ 3,014.8 $ 21,664.8 $ 24,679.6
Debt and equity securities available for sale	Debt and equity securities available for sale at September 30, 2016 and December 31, 2015 were as follows: (Millions) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value September 30, 2016 Debt securities: U.S. government securities $ 1,688.6 $ 111.0 $ (.7 ) $ 1,798.9 States, municipalities and political subdivisions 4,941.5 312.1 (6.9 ) 5,246.7 U.S. corporate securities 8,169.9 627.7 (10.2 ) 8,787.4 Foreign securities 2,969.5 266.6 (6.2 ) 3,229.9 Residential mortgage-backed securities 835.0 25.5 (.5 ) 860.0 Commercial mortgage-backed securities 1,357.4 33.7 (2.7 ) (1) 1,388.4 Other asset-backed securities 1,066.8 13.7 (8.2 ) (1) 1,072.3 Redeemable preferred securities 23.2 5.7 — 28.9 Total debt securities 21,051.9 1,396.0 (35.4 ) 22,412.5 Equity securities 127.0 24.3 (3.2 ) 148.1 Total debt and equity securities (2) $ 21,178.9 $ 1,420.3 $ (38.6 ) $ 22,560.6 December 31, 2015 Debt securities: U.S. government securities $ 1,803.5 $ 68.8 $ (.6 ) $ 1,871.7 States, municipalities and political subdivisions 4,889.5 244.3 (9.3 ) 5,124.5 U.S. corporate securities 7,981.5 339.5 (146.6 ) 8,174.4 Foreign securities 2,910.2 148.3 (61.4 ) 2,997.1 Residential mortgage-backed securities 914.6 16.6 (6.3 ) 924.9 Commercial mortgage-backed securities 1,262.4 17.2 (9.0 ) (1) 1,270.6 Other asset-backed securities 910.4 3.1 (19.2 ) (1) 894.3 Redeemable preferred securities 33.0 11.5 — 44.5 Total debt securities 20,705.1 849.3 (252.4 ) 21,302.0 Equity securities 22.8 4.1 (5.9 ) 21.0 Total debt and equity securities (2) $ 20,727.9 $ 853.4 $ (258.3 ) $ 21,323.0 (1) At September 30, 2016 and December 31, 2015 , we held securities for which we previously recognized $4.9 million and $5.4 million , respectively, of non-credit related impairments in accumulated other comprehensive loss. These securities had a net unrealized capital gain at September 30, 2016 and December 31, 2015 of $0.9 million and $1.9 million , respectively. (2) Investment risks associated with our experience-rated and discontinued products generally do not impact our operating results (refer to Note 18 for additional information on our accounting for discontinued products). At September 30, 2016 , debt and equity securities with a fair value of approximately $3.1 billion , gross unrealized capital gains of $327.8 million and gross unrealized capital losses of $6.6 million and, at December 31, 2015 , debt and equity securities with a fair value of approximately $3.0 billion , gross unrealized capital gains of $208.7 million and gross unrealized capital losses of $68.0 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 September 30, 2016 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 $ 1,419.0 One year through five years 6,789.4 After five years through ten years 5,290.1 Greater than ten years 5,593.3 Residential mortgage-backed securities 860.0 Commercial mortgage-backed securities 1,388.4 Other asset-backed securities 1,072.3 Total $ 22,412.5
Debt and Equity Securities in an Unrealized Capital Loss Position	Summarized below are the debt and equity securities we held at September 30, 2016 and December 31, 2015 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 Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses September 30, 2016 Debt securities: U.S. government securities $ 107.3 $ .4 $ 10.2 $ .3 $ 117.5 $ .7 States, municipalities and political subdivisions 545.0 4.5 125.9 2.4 670.9 6.9 U.S. corporate securities 439.2 1.6 129.2 8.6 568.4 10.2 Foreign securities 266.0 2.0 88.8 4.2 354.8 6.2 Residential mortgage-backed securities 32.5 .1 37.2 .4 69.7 .5 Commercial mortgage-backed securities 396.5 2.7 4.8 — 401.3 2.7 Other asset-backed securities 158.4 2.1 142.1 6.1 300.5 8.2 Total debt securities 1,944.9 13.4 538.2 22.0 2,483.1 35.4 Equity securities 34.6 .9 2.7 2.3 37.3 3.2 Total debt and equity securities (1) $ 1,979.5 $ 14.3 $ 540.9 $ 24.3 $ 2,520.4 $ 38.6 December 31, 2015 Debt securities: U.S. government securities $ 66.8 $ .2 $ 12.6 $ .4 $ 79.4 $ .6 States, municipalities and political subdivisions 714.2 6.1 91.6 3.2 805.8 9.3 U.S. corporate securities 3,168.7 130.8 144.3 15.8 3,313.0 146.6 Foreign securities 1,102.4 50.4 89.2 11.0 1,191.6 61.4 Residential mortgage-backed securities 328.7 2.9 89.5 3.4 418.2 6.3 Commercial mortgage-backed securities 562.0 8.6 23.8 .4 585.8 9.0 Other asset-backed securities 653.5 15.6 67.1 3.6 720.6 19.2 Total debt securities 6,596.3 214.6 518.1 37.8 7,114.4 252.4 Equity securities — 5.0 1.3 .9 1.3 5.9 Total debt and equity securities (1) $ 6,596.3 $ 219.6 $ 519.4 $ 38.7 $ 7,115.7 $ 258.3 (1) At September 30, 2016 and December 31, 2015 , debt and equity securities in an unrealized capital loss position of $6.6 million and $68.0 million , respectively, and with related fair value of $238.6 million and $966.2 million , 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 September 30, 2016 were as follows: Supporting discontinued and experience-rated products Supporting remaining products Total (Millions) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Due to mature: Less than one year $ — $ — $ 135.9 $ .5 $ 135.9 $ .5 One year through five years 4.1 — 657.7 5.3 661.8 5.3 After five years through ten years 78.8 .8 357.1 4.9 435.9 5.7 Greater than ten years 96.1 4.0 381.9 8.5 478.0 12.5 Residential mortgage-backed securities 5.2 — 64.5 .5 69.7 .5 Commercial mortgage-backed securities 51.7 .4 349.6 2.3 401.3 2.7 Other asset-backed securities — — 300.5 8.2 300.5 8.2 Total $ 235.9 $ 5.2 $ 2,247.2 $ 30.2 $ 2,483.1 $ 35.4
Net realized capital gains (losses)	Net realized capital gains for the three and nine months ended September 30, 2016 and 2015 , excluding amounts related to experience-rated contract holders and discontinued products, were as follows: Three Months Ended Nine Months Ended September 30, September 30, (Millions) 2016 2015 2016 2015 OTTI losses on debt securities recognized in earnings $ (.4 ) $ (21.0 ) $ (10.1 ) $ (31.0 ) Other net realized capital gains (losses) 35.2 (12.1 ) 95.6 8.0 Net realized capital gains (losses) $ 34.8 $ (33.1 ) $ 85.5 $ (23.0 )
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 and nine months ended September 30, 2016 and 2015 were as follows: Three Months Ended Nine Months Ended September 30, September 30, (Millions) 2016 2015 2016 2015 Proceeds on sales $ 1,481.4 $ 1,275.4 $ 4,836.2 $ 3,766.6 Gross realized capital gains 31.0 12.7 130.8 58.3 Gross realized capital losses 2.6 19.1 37.7 41.5
Activity in mortgage loan portfolio	During the three and nine months ended September 30, 2016 and 2015 we had the following activity in our mortgage loan portfolio: Three Months Ended Nine Months Ended September 30, September 30, (Millions) 2016 2015 2016 2015 New mortgage loans $ 65.7 $ 132.6 $ 154.5 $ 169.7 Mortgage loans fully repaid 55.6 37.1 141.9 96.1 Mortgage loans foreclosed 7.5 — 7.5 9.0
Mortgage loan internal credit rating	Based upon our most recent assessments at September 30, 2016 and December 31, 2015 , our mortgage loans were given the following credit quality indicators: (In Millions, except credit ratings indicator) September 30, December 31, 1 $ 48.6 $ 65.8 2 to 4 1,452.6 1,466.9 5 and 6 17.3 21.0 Total $ 1,518.5 $ 1,553.7
Schedule of Variable Interest Entities	The total amount of other variable interest holder VIE assets included in long term investments on our balance sheets at September 30, 2016 and December 31, 2015 were as follows: (Millions) September 30, December 31, 2015 Hedge fund investments $ 407.7 $ 418.1 Private equity investments 437.4 443.3 Real estate partnerships 287.3 253.3 Total $ 1,132.4 $ 1,114.7 The carrying value of the total assets and liabilities of our other variable interest holder VIE investments at September 30, 2016 and December 31, 2015 were as follows: (Millions) September 30, December 31, 2015 Assets: Hedge fund investments $ 34,903.8 $ 33,065.7 Private equity investments 26,352.0 28,552.5 Real estate partnerships 6,473.0 6,808.7 Total $ 67,728.8 $ 68,426.9 Liabilities: Hedge fund investments $ 4,110.0 $ 3,535.3 Private equity investments 2,527.8 3,235.7 Real estate partnerships 4,808.6 5,044.5 Total $ 11,446.4 $ 11,815.5
Net Investment Income	Sources of net investment income for the three and nine months ended September 30, 2016 and 2015 were as follows: Three Months Ended Nine Months Ended September 30, September 30, (Millions) 2016 2015 2016 2015 Debt securities $ 186.7 $ 196.7 $ 578.0 $ 594.4 Mortgage loans 24.1 22.6 74.2 66.2 Other investments 17.5 4.7 64.1 67.2 Gross investment income 228.3 224.0 716.3 727.8 Investment expenses (9.9 ) (10.7 ) (29.2 ) (34.2 ) Net investment income (1) $ 218.4 $ 213.3 $ 687.1 $ 693.6 (1) Net investment income includes $47.6 million and $158.3 million for the three and nine months ended September 30, 2016 , respectively, and $50.3 million and $191.7 million for the three and nine months ended September 30, 2015 , respectively, related to investments supporting our experience rated and discontinued products.

Health Care Reform (Tables)

Health Care Reform (Tables)	9 Months Ended
	Sep. 30, 2016
Health Care Reform [Abstract]
Health Care Reform Programs	Our net receivable (payable) related to the 3Rs risk management programs at September 30, 2016 and December 31, 2015 were as follows: At September 30, 2016 At December 31, 2015 (Millions) Reinsurance Risk Adjustment Risk Corridor Reinsurance Risk Adjustment Risk Corridor Current (1) $ 132.9 $ (555.1 ) $ (53.9 ) $ 394.5 $ (710.2 ) $ (8.1 ) Long-term 10.1 49.1 — — — — Total net receivable (payable) $ 143.0 $ (506.0 ) $ (53.9 ) $ 394.5 $ (710.2 ) $ (8.1 ) (1) At September 30, 2016, $41.7 million of ACA reinsurance receivables and $35.4 million of ACA risk adjustment receivables related to the respective 2015 programs. The remainder of the net balances related to the respective 2016 programs.

Other Comprehensive (Loss) In32

Other Comprehensive (Loss) Income (Tables)	9 Months Ended
	Sep. 30, 2016
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 nine months ended September 30, 2016 and 2015 : Net Unrealized Gains (Losses) Pension and OPEB Plans Total Securities Foreign Unrecognized Net Actuarial Losses Unrecognized Prior Service Credit (Millions) Previously Impaired (1) All Other Nine months ended September 30, 2016 Balance at December 31, 2015 $ 18.7 $ 312.4 $ (74.0 ) $ (1,602.3 ) $ 14.9 $ (1,330.3 ) Other comprehensive (loss) income before reclassifications (3.4 ) 403.2 (176.1 ) — — 223.7 Amounts reclassified from accumulated other comprehensive income 4.1 (2 ) (19.5 ) (2 ) 11.3 (3 ) 31.1 (4 ) (2.0 ) (4 ) 25.0 Other comprehensive income (loss) .7 383.7 (164.8 ) 31.1 (2.0 ) 248.7 Balance at September 30, 2016 $ 19.4 $ 696.1 $ (238.8 ) $ (1,571.2 ) $ 12.9 $ (1,081.6 ) Nine months ended September 30, 2015 Balance at December 31, 2014 $ 34.9 $ 568.0 $ (60.9 ) $ (1,670.9 ) $ 17.6 $ (1,111.3 ) Other comprehensive (loss) income before reclassifications (19.7 ) (229.5 ) (36.2 ) — — (285.4 ) Amounts reclassified from accumulated other comprehensive income 6.8 (2 ) 42.2 (2 ) 2.9 (3 ) 31.3 (4 ) (2.0 ) (4 ) 81.2 Other comprehensive (loss) income (12.9 ) (187.3 ) (33.3 ) 31.3 (2.0 ) (204.2 ) Balance at September 30, 2015 $ 22.0 $ 380.7 $ (94.2 ) $ (1,639.6 ) $ 15.6 $ (1,315.5 ) (1) Represents unrealized gains or losses 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 Statements 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 Statements of Income, except for the effective portion of derivatives related to interest rate swaps which are reflected in interest expense during the nine months ended September 30, 2016 or 2015 . Refer to Note 12 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 Statements of Income. Refer to Note 11 for additional information.

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2016
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 September 30, 2016 and December 31, 2015 were as follows: (Millions) Level 1 Level 2 Level 3 Total September 30, 2016 Assets: Debt securities: U.S. government securities $ 1,610.5 $ 188.4 $ — $ 1,798.9 States, municipalities and political subdivisions — 5,245.8 .9 5,246.7 U.S. corporate securities — 8,712.4 75.0 8,787.4 Foreign securities — 3,199.2 30.7 3,229.9 Residential mortgage-backed securities — 860.0 — 860.0 Commercial mortgage-backed securities — 1,357.6 30.8 1,388.4 Other asset-backed securities — 1,072.3 — 1,072.3 Redeemable preferred securities — 27.1 1.8 28.9 Total debt securities 1,610.5 20,662.8 139.2 22,412.5 Equity securities 114.3 — 33.8 148.1 Derivatives — — — — Total $ 1,724.8 $ 20,662.8 $ 173.0 $ 22,560.6 Liabilities: Derivatives $ — $ .2 $ — $ .2 December 31, 2015 Assets: Debt securities: U.S. government securities $ 1,671.0 $ 200.7 $ — $ 1,871.7 States, municipalities and political subdivisions — 5,123.4 1.1 5,124.5 U.S. corporate securities — 8,110.5 63.9 8,174.4 Foreign securities — 2,972.3 24.8 2,997.1 Residential mortgage-backed securities — 924.9 — 924.9 Commercial mortgage-backed securities — 1,270.6 — 1,270.6 Other asset-backed securities — 894.3 — 894.3 Redeemable preferred securities — 39.0 5.5 44.5 Total debt securities 1,671.0 19,535.7 95.3 21,302.0 Equity securities 1.7 — 19.3 21.0 Derivatives — 19.7 — 19.7 Total $ 1,672.7 $ 19,555.4 $ 114.6 $ 21,342.7 Liabilities: Derivatives $ — $ 88.3 $ — $ 88.3
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 our financial instruments carried at adjusted cost or contract value at September 30, 2016 and December 31, 2015 were as follows: Carrying Value Estimated Fair Value (Millions) Level 1 Level 2 Level 3 Total September 30, 2016 Assets: Mortgage loans $ 1,518.5 $ — $ — $ 1,575.7 $ 1,575.7 Bank loans 8.7 — — 8.1 8.1 Equity securities (1) 35.2 N/A N/A N/A N/A Liabilities: Investment contract liabilities: With a fixed maturity 8.7 — — 8.7 8.7 Without a fixed maturity 381.9 — — 381.8 381.8 Long-term debt 20,662.2 — 22,091.8 — 22,091.8 December 31, 2015 Assets: Mortgage loans $ 1,553.7 $ — $ — $ 1,598.7 $ 1,598.7 Bank loans 192.8 — 179.9 7.6 187.5 Equity securities (1) 34.9 N/A N/A N/A N/A Liabilities: Investment contract liabilities: With a fixed maturity 8.6 — — 8.6 8.6 Without a fixed maturity 371.3 — — 351.1 351.1 Long-term debt 7,785.4 — 8,227.3 — 8,227.3 (1) It was not practical to estimate the fair value of these cost-method investments as it represents shares of unlisted companies.
Separate Account Financial Assets	Separate Accounts financial assets at September 30, 2016 and December 31, 2015 were as follows: September 30, 2016 December 31, 2015 (Millions) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Debt securities $ 844.9 $ 2,460.5 $ 3.2 $ 3,308.6 $ 750.4 $ 2,382.0 $ 3.8 $ 3,136.2 Equity securities 167.3 5.5 — 172.8 169.8 5.2 — 175.0 Derivatives — — — — — .2 — .2 Common/collective trusts — 610.6 — 610.6 — 540.2 — 540.2 Total (1) $ 1,012.2 $ 3,076.6 $ 3.2 $ 4,092.0 $ 920.2 $ 2,927.6 $ 3.8 $ 3,851.6 (1) Excludes $225.7 million and $183.5 million of cash and cash equivalents and other receivables at September 30, 2016 and December 31, 2015 , respectively.
Balance Sheet Offsetting Assets	Financial assets, including derivative assets, subject to offsetting and enforceable master netting arrangements at September 30, 2016 and December 31, 2015 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 September 30, 2016 Derivatives $ — $ 14.1 $ — $ 14.1 Total $ — $ 14.1 $ — $ 14.1 December 31, 2015 Derivatives $ 19.7 $ 11.8 $ (16.4 ) $ 15.1 Total $ 19.7 $ 11.8 $ (16.4 ) $ 15.1 (1) There were no amounts offset in our balance sheets at September 30, 2016 or December 31, 2015 .
Balance Sheet Offsetting Liabilities	Financial liabilities, including derivative liabilities, subject to offsetting and enforceable master netting arrangements at September 30, 2016 and December 31, 2015 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 September 30, 2016 Derivatives $ .2 $ — $ — $ .2 Total $ .2 $ — $ — $ .2 December 31, 2015 Derivatives $ 88.3 $ — $ (90.7 ) $ (2.4 ) Total $ 88.3 $ — $ (90.7 ) $ (2.4 ) (1) There were no amounts offset in our balance sheets at September 30, 2016 or December 31, 2015 .

Pension and Other Postretirem34

Pension and Other Postretirement Plans (Tables)	9 Months Ended
	Sep. 30, 2016
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 and nine months ended September 30, 2016 and 2015 were as follows: Pension Plans OPEB Plans Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, (Millions) 2016 2015 2016 2015 2016 2015 2016 2015 Amortization of prior service credit $ (.1 ) $ (.1 ) $ (.3 ) $ (.3 ) $ (.8 ) $ (1.0 ) $ (2.7 ) $ (2.8 ) Interest cost 64.9 65.3 194.8 195.7 2.7 2.7 8.1 8.1 Expected return on plan assets (97.3 ) (104.8 ) (291.9 ) (314.3 ) (.7 ) (.7 ) (1.9 ) (2.2 ) Recognized net actuarial losses 15.4 15.3 46.1 46.1 .6 .7 1.8 2.0 Net periodic benefit (income) cost $ (17.1 ) $ (24.3 ) $ (51.3 ) $ (72.8 ) $ 1.8 $ 1.7 $ 5.3 $ 5.1

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Carrying Value of Long-Term Debt	The carrying value of our long-term debt at September 30, 2016 and December 31, 2015 was as follows: (Millions) September 30, December 31, Senior notes, 5.95%, due March 2017 (1) $ 390.5 $ 402.4 Senior notes, 1.75%, due May 2017 (1) 249.6 249.1 Senior notes, 1.5%, due November 2017 498.6 497.7 Senior notes, floating rate, due December 2017 498.9 — Senior notes, 1.7%, due June 2018 996.6 — Senior notes, 2.2%, due March 2019 373.4 372.9 Senior notes, 1.9%, due June 2019 1,641.2 — Senior notes, 3.95%, due September 2020 744.4 743.4 Senior notes, 2.4%, due June 2021 1,838.3 — Senior notes, 5.45%, due June 2021 664.6 674.9 Senior notes, 4.125%, due June 2021 494.9 494.1 Senior notes, 2.75%, due November 2022 985.0 983.1 Senior notes, 2.8%, due June 2023 1,289.6 — Senior notes, 3.5%, due November 2024 742.3 741.6 Senior notes, 3.2%, due June 2026 2,770.4 — Senior notes, 4.25%, due June 2036 1,480.0 — Senior notes, 6.625%, due June 2036 765.1 765.0 Senior notes, 6.75%, due December 2037 527.3 527.0 Senior notes, 4.5%, due May 2042 477.7 477.1 Senior notes, 4.125%, due November 2042 489.0 488.6 Senior notes, 4.75%, due March 2044 370.6 370.5 Senior notes, 4.375%, due June 2046 2,375.3 — Total long-term debt 20,663.3 7,787.4 Less current portion of long-term debt 640.1 — Less credit facility issuance costs 1.1 2.0 Total long-term debt, less current portion and credit facility issuance costs $ 20,022.1 $ 7,785.4 (1) At September 30, 2016 , our 5.95% senior notes due March 2017 and 1.75% senior notes due May 2017 are each classified as current in our consolidated balance sheet.

Capital Stock (Tables)

Capital Stock (Tables)	9 Months Ended
	Sep. 30, 2016
Class of Stock Disclosures [Abstract]
Dividends declared	During the nine months ended September 30, 2016 our Board declared the following cash dividends: Date Declared Dividend Amount Per Share Stockholders of Record Date Date Paid/ To be Paid Total Dividends (Millions) February 19, 2016 $ .25 April 14, 2016 April 29, 2016 $ 87.6 May 20, 2016 .25 July 14, 2016 July 29, 2016 87.7 September 30, 2016 .25 October 13, 2016 October 28, 2016 87.7
Black Scholes option pricing model	The SARs granted to certain employees during first quarters of 2016 and 2015 had an estimated fair market value of $34.33 and $32.13 per unit, respectively. The fair value per unit was calculated on each respective grant date using a modified Black-Scholes option pricing model using the following assumptions during the first quarters of 2016 and 2015 : 2016 2015 Expected term (in years) 7.11 6.48 Volatility 32.9 % 33.4 % Risk-free interest rate 1.52 % 1.81 % Dividend yield .91 % 1.13 % Initial price $ 103.45 $ 100.50

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Summarized financial information of segments	Summarized financial information of our segment operations for the three and nine months ended September 30, 2016 and 2015 were as follows: (Millions) Health Care Group Insurance Large Case Pensions Corporate Financing Total Company Three Months Ended September 30, 2016 Revenue from external customers $ 14,949.9 $ 563.7 $ 14.7 $ — $ 15,528.3 Operating earnings (loss) (1) 752.5 19.1 5.0 (42.3 ) 734.3 Three Months Ended September 30, 2015 Revenue from external customers $ 14,202.3 $ 557.5 $ 13.0 $ — $ 14,772.8 Operating earnings (loss) (1) 675.4 25.6 4.4 (36.8 ) 668.6 Nine Months Ended September 30, 2016 Revenue from external customers $ 44,932.6 $ 1,683.1 $ 38.9 $ — $ 46,654.6 Operating earnings (loss) (1) 2,365.8 90.3 9.1 (126.5 ) 2,338.7 Nine Months Ended September 30, 2015 Revenue from external customers (2) $ 42,904.9 $ 1,677.6 $ 34.9 $ — $ 44,617.4 Operating earnings (loss) (1) 2,219.0 114.3 12.7 (111.0 ) 2,235.0 (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. (2) In the nine months ended September 30, 2015, we received proceeds of $71.3 million ( $109.6 million pretax), net of legal costs, in connection with a litigation settlement. These net proceeds were recorded in fees and other revenue in our GAAP Consolidated Statements of Income.
Reconciliation of Operating Earnings to Net Income	A reconciliation of net income attributable to Aetna to operating earnings (1) for the three and nine months ended September 30, 2016 and 2015 was as follows: Three Months Ended Nine Months Ended September 30, September 30, (Millions) 2016 2015 2016 2015 Net income attributable to Aetna (GAAP measure) $ 603.9 $ 560.1 $ 2,131.6 $ 2,069.4 Transaction and integration-related costs 164.0 62.3 333.1 138.6 Reduction of reserve for anticipated future losses on discontinued products — — (128.5 ) — Litigation-related proceeds — — — (109.6 ) Amortization of other acquired intangible assets 61.4 65.1 187.0 192.0 Net realized capital (gains) losses (34.8 ) 33.1 (85.5 ) 23.0 Income tax benefit (60.2 ) (52.0 ) (99.0 ) (78.4 ) Operating earnings (1) $ 734.3 $ 668.6 $ 2,338.7 $ 2,235.0 (1) In addition to net realized capital losses and gains 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 during the three and nine months ended September 30, 2016 and 2015 related to the acquisitions of Coventry and bswift LLC (“bswift”) and the Humana Acquisition. 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, as well as the cost of the Bridge Credit Agreement and the Term Loan Agreement executed in connection with the Humana Acquisition, which are reflected in our GAAP Consolidated Statements of Income in interest expense. Transaction costs also include the negative cost of carry associated with the 2016 Humana-related senior notes. Prior to the closing of the Humana Acquisition, the negative cost of carry associated with the 2016 Humana-related senior notes is excluded from operating earnings. The components of the negative cost of carry are reflected in our GAAP Consolidated Statements of Income in interest expense and net investment income. On and after the closing of the Humana Acquisition, the interest expense and net investment income associated with the 2016 Humana-related senior notes no longer will be excluded from operating earnings. • In 1993, we discontinued the sale of our fully guaranteed large case pensions products and established a reserve for anticipated future losses on these products, which we review quarterly. During the nine months ended September 30, 2016, we reduced the reserve for anticipated future losses on discontinued products. We believe excluding any changes in the reserve for anticipated future losses on discontinued products from operating earnings provides more useful information as to our continuing products and is consistent with the treatment of the operating results of these discontinued products, which are credited or charged to the reserve and do not affect our operating results. Refer to Note 18 for additional information on the reduction of the reserve for anticipated future losses on discontinued products. • In the nine months ended September 30, 2015, we received proceeds, net of legal costs, in connection with a litigation settlement. These net proceeds were recorded in fees and other revenue in our GAAP Consolidated Statements of Income. • The corresponding tax benefit or expense related to the items excluded from operating earnings discussed above. The tax benefit or expense was calculated utilizing the appropriate tax rate for each individual item excluded from operating earnings.

Discontinued Products (Tables)

Discontinued Products (Tables)	9 Months Ended
	Sep. 30, 2016
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 nine months ended September 30, 2016 and 2015 was as follows (pretax): (Millions) 2016 2015 Reserve, beginning of period $ 1,067.2 $ 1,014.7 Operating loss (19.9 ) (2.1 ) Net realized capital gains 49.5 57.2 Reserve reduction (128.5 ) — Reserve, end of period $ 968.3 $ 1,069.8
Assets and Liabilities Supporting Discontinued Products	Assets and liabilities supporting discontinued products (1) at September 30, 2016 and December 31, 2015 were as follows: (Millions) 2016 2015 Assets: Debt and equity securities available for sale $ 2,082.5 $ 2,019.6 Mortgage loans 378.5 396.0 Other investments 658.1 643.5 Total investments 3,119.1 3,059.1 Other assets 87.1 128.9 Current and deferred income taxes — 20.5 Receivable from continuing products (2) 545.2 602.0 Total assets $ 3,751.4 $ 3,810.5 Liabilities: Future policy benefits $ 2,373.0 $ 2,493.5 Reserve for anticipated future losses on discontinued products 968.3 1,067.2 Current and deferred income taxes 43.1 — Other liabilities (3) 367.0 249.8 Total liabilities $ 3,751.4 $ 3,810.5 (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.

Summary of Significant Accoun39

Summary of Significant Accounting Policies (Details) $ in Millions	Dec. 31, 2015USD ($)
Accounting Policies [Abstract]
Unamortized Debt Issuance Expense	$ 43

Proposed Acquisition (Details)

Proposed Acquisition (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)$ / shares	Dec. 31, 2015USD ($)
Business Acquisition [Line Items]
Business Acquisition Estimated Purchase Price	$ 37,000
Cash To Be Received By Shareholders Upon Acquisition Per Share | $ / shares	$ 125
Exchange Ratio Used In Calculation Of Merger Consideration	0.8375
Long-term Debt	$ 20,663.3	$ 7,787.4
Disposal Group, Including Discontinued Operation, Consideration	76
Debt Issued for Humana Acquisition [Domain]
Business Acquisition [Line Items]
Debt Instrument, Face Amount	13,000
Long-term Debt	$ 10,200
Debt Instrument, Redemption Price, Percentage	101.00%

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income attributable to Aetna		$ 603.9	$ 560.1	$ 2,131.6	$ 2,069.4
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Weighted average shares used to compute basic EPS (in shares)		351.4	349.2	351.1	349.2
Dilutive effect of outstanding stock-based compensation awards (in shares)		2.9	3.3	3	3.3
Weighted average shares used to compute diluted EPS (in shares)		354.3	352.5	354.1	352.5
Basic EPS (in dollars per share)		$ 1.72	$ 1.60	$ 6.07	$ 5.93
Diluted EPS (in dollars per share)		$ 1.70	$ 1.59	$ 6.02	$ 5.87
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]	0	0.1	0.1	0.7
Other Securities [Member]
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)	[2]	0.7	0.5	0.8	0.8
[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]	Performance stock units ("PSUs"), certain market stock units ("MSUs") with performance conditions, and performance stock appreciation rights ("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 ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Selling expenses		$ 408.6	$ 393	$ 1,245.4	$ 1,213.6
General and administrative expenses:
Salaries and related benefits		1,258.1	1,242.3	3,737.2	3,665.3
Other general and administrative expenses	[1]	1,164	1,193.8	3,494.8	3,566.2
Total general and administrative expenses		2,422.1	2,436.1	7,232	7,231.5
Total operating expenses		2,830.7	2,829.1	8,477.4	8,445.1
Health Insurer Fee		210.6	209.7	627.6	642.2
Contribution to ACA Reinsurance Program		$ 29.6	$ 51.6	$ 88.6	$ 157.4
[1]	The three and nine months ended September 30, 2016 include estimated fees mandated by the ACA (as defined in Note 8) comprised primarily of the health insurer fee of $210.6 million and $627.6 million, respectively, and our estimated contribution to the funding of the ACA’s reinsurance program of $29.6 million and $88.6 million, respectively. The three and nine months ended September 30, 2015 include estimated fees mandated by the ACA comprised primarily of the health insurer fee of $209.7 million and $642.2 million, respectively, and our estimated contribution to the funding of the ACA’s reinsurance program of $51.6 million and $157.4 million, respectively.

Cash and Cash Equivalents (Deta

Cash and Cash Equivalents (Details) $ in Billions	Sep. 30, 2016USD ($)
Cash Equivalents [Member]
Cash and Cash Equivalents [Line Items]
Cash Equivalents, at Carrying Value	$ 13

Investments (Details)

Investments (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Total Investments [Line Items]
Current	$ 2,982.2	$ 3,014.8
Long-term investments	22,756.1	21,664.8
Total investments	25,738.3	24,679.6
Debt And Equity Securities Available For Sale [Member]
Total Investments [Line Items]
Current	2,813.8	2,877.1
Long-term investments	19,746.8	18,445.9
Total investments	22,560.6	21,323
Mortgage Loans [Member]
Total Investments [Line Items]
Current	168.4	126.9
Long-term investments	1,350.1	1,426.8
Total investments	1,518.5	1,553.7
Other Investments [Member]
Total Investments [Line Items]
Current	0	10.8
Long-term investments	1,659.2	1,792.1
Total investments	$ 1,659.2	$ 1,802.9

Investments - Debt and Equity S

Investments - Debt and Equity Securities (Details) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
		Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Non-credit related impairments previously recognized in other comprehensive income		$ 4.9	$ 5.4
Available-for-sale Securities, Amortized Cost Basis	[1]	21,178.9	20,727.9
Available-for-sale Securities, Gross Unrealized Gains	[1]	1,420.3	853.4
Available-for-sale Securities, Gross Unrealized Losses	[1]	(38.6)	(258.3)
Available-for-sale Securities, Fair Value Disclosure		22,560.6	21,323	[1]
Net Unrealized Capital (Loss) Gains		0.9	1.9
Supporting Discontinued And Experience Rated Products [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains		327.8	208.7
Available-for-sale Securities, Gross Unrealized Losses		(6.6)	(68)
Available-for-sale Securities, Fair Value Disclosure		3,100	3,000
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis		21,051.9	20,705.1
Available-for-sale Securities, Gross Unrealized Gains		1,396	849.3
Available-for-sale Securities, Gross Unrealized Losses		(35.4)	(252.4)
Available-for-sale Securities, Fair Value Disclosure		22,412.5	21,302
US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis		1,688.6	1,803.5
Available-for-sale Securities, Gross Unrealized Gains		111	68.8
Available-for-sale Securities, Gross Unrealized Losses		(0.7)	(0.6)
Available-for-sale Securities, Fair Value Disclosure		1,798.9	1,871.7
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis		4,941.5	4,889.5
Available-for-sale Securities, Gross Unrealized Gains		312.1	244.3
Available-for-sale Securities, Gross Unrealized Losses		(6.9)	(9.3)
Available-for-sale Securities, Fair Value Disclosure		5,246.7	5,124.5
Domestic Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis		8,169.9	7,981.5
Available-for-sale Securities, Gross Unrealized Gains		627.7	339.5
Available-for-sale Securities, Gross Unrealized Losses		(10.2)	(146.6)
Available-for-sale Securities, Fair Value Disclosure		8,787.4	8,174.4
Foreign Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis		2,969.5	2,910.2
Available-for-sale Securities, Gross Unrealized Gains		266.6	148.3
Available-for-sale Securities, Gross Unrealized Losses		(6.2)	(61.4)
Available-for-sale Securities, Fair Value Disclosure		3,229.9	2,997.1
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis		835	914.6
Available-for-sale Securities, Gross Unrealized Gains		25.5	16.6
Available-for-sale Securities, Gross Unrealized Losses		(0.5)	(6.3)
Available-for-sale Securities, Fair Value Disclosure		860	924.9
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis		1,357.4	1,262.4
Available-for-sale Securities, Gross Unrealized Gains		33.7	17.2
Available-for-sale Securities, Gross Unrealized Losses	[2]	(2.7)	(9)
Available-for-sale Securities, Fair Value Disclosure		1,388.4	1,270.6
Other Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis		1,066.8	910.4
Available-for-sale Securities, Gross Unrealized Gains		13.7	3.1
Available-for-sale Securities, Gross Unrealized Losses	[2]	(8.2)	(19.2)
Available-for-sale Securities, Fair Value Disclosure		1,072.3	894.3
Redeemable Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis		23.2	33
Available-for-sale Securities, Gross Unrealized Gains		5.7	11.5
Available-for-sale Securities, Gross Unrealized Losses		0	0
Available-for-sale Securities, Fair Value Disclosure		28.9	44.5
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis		127	22.8
Available-for-sale Securities, Gross Unrealized Gains		24.3	4.1
Available-for-sale Securities, Gross Unrealized Losses		(3.2)	(5.9)
Available-for-sale Securities, Fair Value Disclosure		$ 148.1	$ 21
[1]	Investment risks associated with our experience-rated and discontinued products generally do not impact our operating results (refer to Note 18 for additional information on our accounting for discontinued products). At September 30, 2016, debt and equity securities with a fair value of approximately $3.1 billion, gross unrealized capital gains of $327.8 million and gross unrealized capital losses of $6.6 million and, at December 31, 2015, debt and equity securities with a fair value of approximately $3.0 billion, gross unrealized capital gains of $208.7 million and gross unrealized capital losses of $68.0 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 September 30, 2016 and December 31, 2015, we held securities for which we previously recognized $4.9 million and $5.4 million, respectively, of non-credit related impairments in accumulated other comprehensive loss. These securities had a net unrealized capital gain at September 30, 2016 and December 31, 2015 of $0.9 million and $1.9 million, respectively.

Investments - Debt Securities b

Investments - Debt Securities by Maturity (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Available-for-sale Securities, Debt Maturities [Abstract]
Available-for-sale Securities, Fair Value Disclosure	$ 22,560.6	$ 21,323	[1]
Debt Securities [Member]
Available-for-sale Securities, Debt Maturities [Abstract]
Available-for-sale Securities, Fair Value Disclosure	22,412.5	21,302
Available-for-sale Securities With Established Maturities [Member]
Available-for-sale Securities, Debt Maturities [Abstract]
Due To Mature Less Than One Year	1,419
Due to mature one year through five years	6,789.4
Due to mature after five years through ten years	5,290.1
Due to mature greater than ten years	$ 5,593.3
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available For Sale Securities, Weighted Average Duration Of Securities	2 years 329 days
Available-for-sale Securities, Debt Maturities [Abstract]
Available-for-sale Securities, Fair Value Disclosure	$ 860	924.9
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available For Sale Securities, Weighted Average Duration Of Securities	6 years 292 days
Available-for-sale Securities, Debt Maturities [Abstract]
Available-for-sale Securities, Fair Value Disclosure	$ 1,388.4	1,270.6
Other Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available For Sale Securities, Weighted Average Duration Of Securities	1 year 128 days
Available-for-sale Securities, Debt Maturities [Abstract]
Available-for-sale Securities, Fair Value Disclosure	$ 1,072.3	$ 894.3
[1]	Investment risks associated with our experience-rated and discontinued products generally do not impact our operating results (refer to Note 18 for additional information on our accounting for discontinued products). At September 30, 2016, debt and equity securities with a fair value of approximately $3.1 billion, gross unrealized capital gains of $327.8 million and gross unrealized capital losses of $6.6 million and, at December 31, 2015, debt and equity securities with a fair value of approximately $3.0 billion, gross unrealized capital gains of $208.7 million and gross unrealized capital losses of $68.0 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 P

Investments - Unrealized Loss Position (Details) - USD ($) $ in Millions		9 Months Ended		12 Months Ended
		Sep. 30, 2016		Dec. 31, 2015
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	[1]	$ 1,979.5		$ 6,596.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	[1]	14.3		219.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	[1]	540.9		519.4
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	[1]	24.3		38.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		2,520.4	[1]	7,115.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		38.6	[1]	258.3
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		238.6		966.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		6.6		68
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		1,944.9		6,596.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses		13.4		214.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		538.2		518.1
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses		22		37.8
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		2,483.1	[1]	7,114.4
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		35.4	[1]	252.4
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		235.9
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		5.2
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		2,247.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		30.2
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		107.3		66.8
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses		0.4		0.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		10.2		12.6
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses		0.3		0.4
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		117.5	[1]	79.4
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		0.7	[1]	0.6
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		545		714.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses		4.5		6.1
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		125.9		91.6
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses		2.4		3.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		670.9	[1]	805.8
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		6.9	[1]	9.3
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		439.2		3,168.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses		1.6		130.8
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		129.2		144.3
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses		8.6		15.8
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		568.4	[1]	3,313
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		10.2	[1]	146.6
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		266		1,102.4
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses		2		50.4
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		88.8		89.2
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses		4.2		11
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		354.8	[1]	1,191.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		6.2	[1]	61.4
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		32.5		328.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses		0.1		2.9
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		37.2		89.5
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses		0.4		3.4
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		69.7	[1]	418.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		0.5	[1]	6.3
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		396.5		562
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses		2.7		8.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		4.8		23.8
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses		0		0.4
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		401.3	[1]	585.8
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		2.7	[1]	9
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		158.4		653.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses		2.1		15.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		142.1		67.1
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses		6.1		3.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		300.5	[1]	720.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		8.2	[1]	19.2
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		34.6		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses		0.9		5
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		2.7		1.3
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses		2.3		0.9
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		37.3	[1]	1.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		$ 3.2	[1]	$ 5.9
[1]	At September 30, 2016 and December 31, 2015, debt and equity securities in an unrealized capital loss position of $6.6 million and $68.0 million, respectively, and with related fair value of $238.6 million and $966.2 million, respectively, related to experience-rated and discontinued products.

Investments - Unrealized Loss48

Investments - Unrealized Loss Position Maturities (Details) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2016		Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	$ 38.6	[1]	$ 258.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,520.4	[1]	7,115.7
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	35.4	[1]	252.4
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,483.1	[1]	7,114.4
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	30.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,247.2
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	6.6		68
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	238.6		$ 966.2
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	5.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	235.9
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	0.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	135.9
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	0.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	135.9
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	5.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	661.8
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	5.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	657.7
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
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4.1
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	5.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	435.9
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	4.9
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	357.1
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	0.8
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	78.8
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	12.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	478
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	8.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	381.9
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	4
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	96.1
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	0.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	69.7
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	0.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	64.5
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
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	5.2
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	2.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	401.3
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	2.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	349.6
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	0.4
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	51.7
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	8.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	300.5
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	8.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	300.5
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
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 0
[1]	At September 30, 2016 and December 31, 2015, debt and equity securities in an unrealized capital loss position of $6.6 million and $68.0 million, respectively, and with related fair value of $238.6 million and $966.2 million, respectively, related to experience-rated and discontinued products.

Investments - Realized Gains (D

Investments - Realized Gains (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
OTTI losses on debt securities recognized in earnings	$ (0.4)	$ (21)	$ (10.1)	$ (31)
Net realized capital gains (losses), excluding OTTI losses on securities	35.2	(12.1)	95.6	8
Net realized capital gains (losses)	34.8	(33.1)	85.5	(23)
Debt Securities [Member]
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Proceeds On Sales	1,481.4	1,275.4	4,836.2	3,766.6
Gross Realized Capital Gains	31	12.7	130.8	58.3
Gross Realized Capital Losses	$ 2.6	$ 19.1	$ 37.7	$ 41.5

Investments - Mortgage Loans (D

Investments - Mortgage Loans (Details) - Commercial Real Estate [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Movement in Mortgage Loans on Real Estate [Roll Forward]
New Mortgage Loans	$ 65.7	$ 132.6	$ 154.5	$ 169.7
Mortgage loans fully repaid	55.6	37.1	141.9	96.1
Mortgage Loans on Real Estate, Foreclosures	7.5	$ 0	7.5	$ 9
Mortgage Loans on Real Estate	1,518.5		1,518.5		$ 1,553.7
Category 1 [Member]
Movement in Mortgage Loans on Real Estate [Roll Forward]
Mortgage Loans on Real Estate	48.6		48.6		65.8
Category 2 to 4 [Member]
Movement in Mortgage Loans on Real Estate [Roll Forward]
Mortgage Loans on Real Estate	1,452.6		1,452.6		1,466.9
Categories 5 and 6 [Member]
Movement in Mortgage Loans on Real Estate [Roll Forward]
Mortgage Loans on Real Estate	17.3		17.3		21
Category 7 [Member]
Movement in Mortgage Loans on Real Estate [Roll Forward]
Mortgage Loans on Real Estate	$ 0		$ 0		$ 0

Investments - Variable Interest

Investments - Variable Interest Entities and Noncontrolling Interests (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Long-term investments	$ 22,756.1		$ 22,756.1		$ 21,664.8
Variable Interest Entity Assets	67,728.8		67,728.8		68,426.9
Stockholders' Equity Attributable to Noncontrolling Interest	60.8		60.8		64.3
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	11,446.4		11,446.4		11,815.5
Noncontrolling Interest [Abstract]
Net income (loss) attributable to non-controlling interest	(6.7)	$ 2.3	(3.5)	$ 3.9
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Long-term investments	500		500		477
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Long-term investments	1,132.4		1,132.4		1,114.7
Hedge Funds [Member]
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Variable Interest Entity Assets	34,903.8		34,903.8		33,065.7
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	4,110		4,110		3,535.3
Private Equity Funds [Member]
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Variable Interest Entity Assets	26,352		26,352		28,552.5
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	2,527.8		2,527.8		3,235.7
Real Estate Partnerships [Member]
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Variable Interest Entity Assets	6,473		6,473		6,808.7
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	4,808.6		4,808.6		5,044.5
Noncontrolling Interest [Member]
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Stockholders' Equity Attributable to Noncontrolling Interest	60.8	$ 63.7	60.8	63.7	64.3	$ 69.2
Noncontrolling Interest [Abstract]
Net income (loss) attributable to non-controlling interest			(3.5)	$ 3.9
Hedge Funds [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Long-term investments	407.7		407.7		418.1
Private Equity Funds [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Long-term investments	437.4		437.4		443.3
Real Estate Partnerships [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Long-term investments	$ 287.3		$ 287.3		$ 253.3

Investments - Investment Income

Investments - Investment Income (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income		$ 228.3	$ 224	$ 716.3	$ 727.8
Investment expenses		(9.9)	(10.7)	(29.2)	(34.2)
Net Investment Income	[1]	218.4	213.3	687.1	693.6
Supporting Discontinued And Experience Rated Products [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net Investment Income		47.6	50.3	158.3	191.7
Debt Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income		186.7	196.7	578	594.4
Mortgage Loans [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income		24.1	22.6	74.2	66.2
Other Investments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income		$ 17.5	$ 4.7	$ 64.1	$ 67.2
[1]	Net investment income includes $47.6 million and $158.3 million for the three and nine months ended September 30, 2016, respectively, and $50.3 million and $191.7 million for the three and nine months ended September 30, 2015, respectively

Health Care Reform (Details)

Health Care Reform (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Reinsurance Recoverable Under Health Care Reform	$ 143	$ 394.5
Net health care reform risk adjustment payable (receivable)	(506)	(710.2)
Health care reform risk corridor net	$ (53.9)	(8.1)
Health care reform risk corridor proration rate	12.60%
2015 Program Year [Domain]
Reinsurance Recoverable Under Health Care Reform	$ 41.7
Net health care reform risk adjustment payable (receivable)	35.4
Current [Member]
Reinsurance Recoverable Under Health Care Reform	132.9	394.5
Net health care reform risk adjustment payable (receivable)	(555.1)	(710.2)
Health care reform risk corridor net	(53.9)	(8.1)
Long-term [Member]
Reinsurance Recoverable Under Health Care Reform	10.1	0
Net health care reform risk adjustment payable (receivable)	49.1	0
Health care reform risk corridor net	0	$ 0
Maximum [Member]
Health care reform risk corridor net	$ 377

Other Comprehensive (Loss) In54

Other Comprehensive (Loss) Income (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period				$ (1,330.3)
Other comprehensive (loss) income		$ 10.8	$ (42.4)	248.7	$ (204.2)
Balance at end of period		(1,081.6)		(1,081.6)
Net Unrealized Gains (Losses) Previously Impaired Securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	[1]			18.7	34.9
Net unrealized gains (losses)	[1]			(3.4)	(19.7)
Net unrealized gains (losses) on securities, reclassification of gains to earnings	[1],[2]			4.1	6.8
Other comprehensive (loss) income	[1]			0.7	(12.9)
Balance at end of period	[1]	19.4	22	19.4	22
Net Unrealized Gains (Losses) All Other Securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period				312.4	568
Net unrealized gains (losses)				403.2	(229.5)
Net unrealized gains (losses) on securities, reclassification of gains to earnings	[2]			(19.5)	42.2
Other comprehensive (loss) income				383.7	(187.3)
Balance at end of period		696.1	380.7	696.1	380.7
Net Unrealized Gains (Losses) Foreign Currency And Derivatives [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period				(74)	(60.9)
Net unrealized gains (losses)				(176.1)	(36.2)
Foreign currency and derivatives reclassification of losses to earnings	[3]			11.3	2.9
Other comprehensive (loss) income				(164.8)	(33.3)
Balance at end of period		(238.8)	(94.2)	(238.8)	(94.2)
Pension And OPEB Plans Unrecognized Net Actuarial (Losses) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period				(1,602.3)	(1,670.9)
Other comprehensive income, Pensions and Other Post Retirement Employee Benefit Plans, net of tax				0	0
Less: amortization of net actuarial losses	[4]			31.1	31.3
Other comprehensive (loss) income				31.1	31.3
Balance at end of period		(1,571.2)	(1,639.6)	(1,571.2)	(1,639.6)
Pension And OPEB Plans Unrecognized Prior Service Cost [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period				14.9	17.6
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	[4]			(2)	(2)
Other comprehensive (loss) income				(2)	(2)
Balance at end of period		12.9	15.6	12.9	15.6
Accumulated Other Comprehensive Loss [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period				(1,330.3)	(1,111.3)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent				223.7	(285.4)
Other Comprehensive Income Loss Net Of Tax Reclassification To Earnings				25	81.2
Other comprehensive (loss) income				248.7	(204.2)
Balance at end of period		$ (1,081.6)	$ (1,315.5)	$ (1,081.6)	$ (1,315.5)
[1]	Represents unrealized gains or losses 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 Statements 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 Statements of Income, except for the effective portion of derivatives related to interest rate swaps which are reflected in interest expense during the nine months ended September 30, 2016 or 2015. Refer to Note 12 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 Statements of Income. Refer to Note 11 for additional information.

Financial Instruments - Fair Va

Financial Instruments - Fair Value Measurements (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	$ 29,000,000		$ 62,000,000
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	22,560,600,000		22,560,600,000		$ 21,323,000,000	[1]
Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	22,412,500,000		22,412,500,000		21,302,000,000
US Government Agencies Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	1,798,900,000		1,798,900,000		1,871,700,000
US States and Political Subdivisions Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	5,246,700,000		5,246,700,000		5,124,500,000
Domestic Corporate Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	8,787,400,000		8,787,400,000		8,174,400,000
Foreign Corporate Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	3,229,900,000		3,229,900,000		2,997,100,000
Residential Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	860,000,000		860,000,000		924,900,000
Commercial Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	1,388,400,000		1,388,400,000		1,270,600,000
Other Asset-Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	1,072,300,000		1,072,300,000		894,300,000
Redeemable Preferred Stock [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	28,900,000		28,900,000		44,500,000
Equity Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	148,100,000		148,100,000		21,000,000
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers between Level 1 and Level 2	0	$ 0	0	$ 0
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities	200,000		200,000		88,300,000
Assets, Fair Value Disclosure [Abstract]
Derivative Assets	0		0		19,700,000
Assets, Fair Value Disclosure	22,560,600,000		22,560,600,000		21,342,700,000
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	22,412,500,000		22,412,500,000		21,302,000,000
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	1,798,900,000		1,798,900,000		1,871,700,000
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	5,246,700,000		5,246,700,000		5,124,500,000
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Corporate Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	8,787,400,000		8,787,400,000		8,174,400,000
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Corporate Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	3,229,900,000		3,229,900,000		2,997,100,000
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Residential Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	860,000,000		860,000,000		924,900,000
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	1,388,400,000		1,388,400,000		1,270,600,000
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Other Asset-Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	1,072,300,000		1,072,300,000		894,300,000
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Redeemable Preferred Stock [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	28,900,000		28,900,000		44,500,000
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	148,100,000		148,100,000		21,000,000
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	1,575,700,000		1,575,700,000		1,598,700,000
Bank loans	8,100,000		8,100,000		187,500,000
Investment contracts with a fixed maturity	8,700,000		8,700,000		8,600,000
Investment contracts without a fixed maturity	381,800,000		381,800,000		351,100,000
Long-term debt	22,091,800,000		22,091,800,000		8,227,300,000
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	1,518,500,000		1,518,500,000		1,553,700,000
Bank loans	8,700,000		8,700,000		192,800,000
Equity Securities (Cost Method)	35,200,000		35,200,000		34,900,000
Investment contracts with a fixed maturity	8,700,000		8,700,000		8,600,000
Investment contracts without a fixed maturity	381,900,000		381,900,000		371,300,000
Long-term debt	20,662,200,000		20,662,200,000		7,785,400,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities	0		0		0
Assets, Fair Value Disclosure [Abstract]
Derivative Assets	0		0		0
Assets, Fair Value Disclosure	1,724,800,000		1,724,800,000		1,672,700,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	1,610,500,000		1,610,500,000		1,671,000,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	1,610,500,000		1,610,500,000		1,671,000,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Corporate Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Corporate Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Residential Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other Asset-Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Redeemable Preferred Stock [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	114,300,000		114,300,000		1,700,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans	0		0		0
Bank loans	0		0		0
Investment contracts with a fixed maturity	0		0		0
Investment contracts without a fixed maturity	0		0		0
Long-term debt	0		0		0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities	200,000		200,000		88,300,000
Assets, Fair Value Disclosure [Abstract]
Derivative Assets	0		0		19,700,000
Assets, Fair Value Disclosure	20,662,800,000		20,662,800,000		19,555,400,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	20,662,800,000		20,662,800,000		19,535,700,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	188,400,000		188,400,000		200,700,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	5,245,800,000		5,245,800,000		5,123,400,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Corporate Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	8,712,400,000		8,712,400,000		8,110,500,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Corporate Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	3,199,200,000		3,199,200,000		2,972,300,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Residential Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	860,000,000		860,000,000		924,900,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	1,357,600,000		1,357,600,000		1,270,600,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Other Asset-Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	1,072,300,000		1,072,300,000		894,300,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Redeemable Preferred Stock [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	27,100,000		27,100,000		39,000,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans	0		0		0
Bank loans	0		0		179,900,000
Investment contracts with a fixed maturity	0		0		0
Investment contracts without a fixed maturity	0		0		0
Long-term debt	22,091,800,000		22,091,800,000		8,227,300,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities	0		0		0
Assets, Fair Value Disclosure [Abstract]
Derivative Assets	0		0		0
Assets, Fair Value Disclosure	173,000,000		173,000,000		114,600,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	139,200,000		139,200,000		95,300,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	900,000		900,000		1,100,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Corporate Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	75,000,000		75,000,000		63,900,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Corporate Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	30,700,000		30,700,000		24,800,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Residential Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	30,800,000		30,800,000		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Other Asset-Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Redeemable Preferred Stock [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	1,800,000		1,800,000		5,500,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Brokered Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	112,000,000		112,000,000		78,000,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale Securities, Fair Value Disclosure	33,800,000		33,800,000		19,300,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans	1,575,700,000		1,575,700,000		1,598,700,000
Bank loans	8,100,000		8,100,000		7,600,000
Investment contracts with a fixed maturity	8,700,000		8,700,000		8,600,000
Investment contracts without a fixed maturity	381,800,000		381,800,000		351,100,000
Long-term debt	$ 0		$ 0		$ 0
[1]	Investment risks associated with our experience-rated and discontinued products generally do not impact our operating results (refer to Note 18 for additional information on our accounting for discontinued products). At September 30, 2016, debt and equity securities with a fair value of approximately $3.1 billion, gross unrealized capital gains of $327.8 million and gross unrealized capital losses of $6.6 million and, at December 31, 2015, debt and equity securities with a fair value of approximately $3.0 billion, gross unrealized capital gains of $208.7 million and gross unrealized capital losses of $68.0 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 - Separat

Financial Instruments - Separate Accounts Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Separate Account Assets	$ 4,317.7	$ 4,035.1
Fair Value, Measurements, Recurring [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Separate Account Assets	4,092	3,851.6
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	1,012.2	920.2
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	3,076.6	2,927.6
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	3.2	3.8
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Separate Account Assets	3,308.6	3,136.2
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	844.9	750.4
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	2,460.5	2,382
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	3.2	3.8
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Separate Account Assets	172.8	175
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	167.3	169.8
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	5.5	5.2
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
Derivatives [Member] | Fair Value, Measurements, Recurring [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Separate Account Assets	0	0.2
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	0.2
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
Common/Collective Trusts [Member] | Fair Value, Measurements, Recurring [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Separate Account Assets	610.6	540.2
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	610.6	540.2
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
Cash and Cash Equivalents [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Separate Account Assets	$ 225.7	$ 183.5

Financial Instruments - Balance

Financial Instruments - Balance Sheet Offsetting (Details) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	[1]	$ 0	$ 19.7
Derivative, Collateral, Obligation to Return Securities		14.1	11.8
Derivative, Collateral, Obligation to Return Cash		0	16.4
Derivative Asset, Fair Value, Amount Offset Against Collateral		14.1	15.1
Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed, Gross	[1]	0	19.7
Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed, Collateral, Obligation to Return Securities		14.1	11.8
Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed, Collateral, Obligation to Return Cash		0	16.4
Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed, Amount Offset Against Collateral		14.1	15.1
Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Gross	[2]	0.2	88.3
Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Collateral, Right to Reclaim Securities		0	0
Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Collateral, Right to Reclaim Cash		0	(90.7)
Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Amount Offset Against Collateral		0.2	2.4
Derivative Liability, Fair Value, Gross Liability	[2]	0.2	88.3
Derivative, Collateral, Right to Reclaim Securities		0	0
Derivative, Collateral, Right to Reclaim Cash		0	(90.7)
Derivative Liability, Fair Value, Amount Offset Against Collateral		$ 0.2	$ 2.4
[1]	There were no amounts offset in our balance sheets at September 30, 2016 or December 31, 2015.
[2]	There were no amounts offset in our balance sheets at September 30, 2016 or December 31, 2015.

Pension and Other Postretirem58

Pension and Other Postretirement Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Amortization of prior service credit	$ (0.1)	$ (0.1)	$ (0.3)	$ (0.3)
Interest cost	64.9	65.3	194.8	195.7
Expected Return on Plan Assets	(97.3)	(104.8)	(291.9)	(314.3)
Amortization of net actuarial losses	15.4	15.3	46.1	46.1
Net periodic benefit (income) cost	(17.1)	(24.3)	(51.3)	(72.8)
OPEB Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Amortization of prior service credit	(0.8)	(1)	(2.7)	(2.8)
Interest cost	2.7	2.7	8.1	8.1
Expected Return on Plan Assets	(0.7)	(0.7)	(1.9)	(2.2)
Amortization of net actuarial losses	0.6	0.7	1.8	2
Net periodic benefit (income) cost	$ 1.8	$ 1.7	$ 5.3	$ 5.1

Debt (Details)

Debt (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2016	Sep. 30, 2015	Jun. 02, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Federal Home Loan Bank, Maximum Amount Available		$ 902		$ 902
Federal Home Loan Bank, Amount Outstanding		0		0			$ 0
Long-term Debt		20,663.3		20,663.3			7,787.4
Current portion of long-term debt		640.1		640.1			0
Unamortized Debt Issuance Expense							43
Long-term debt, less current portion		20,022.1		20,022.1			7,785.4
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net		30		30
Senior Notes, 5.95%, Due 2017 [Member]
Debt Instrument [Line Items]
Long-term Debt	[1]	$ 390.5		$ 390.5			$ 402.4
Debt Instrument, Interest Rate, Stated Percentage		5.95%		5.95%			5.95%
Senior Notes, 1.75%, Due 2017 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 249.6		$ 249.6			$ 249.1
Debt Instrument, Interest Rate, Stated Percentage		1.75%		1.75%			1.75%
Senior Notes, 1.5%, Due 2017 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 498.6		$ 498.6			$ 497.7
Debt Instrument, Interest Rate, Stated Percentage		1.50%		1.50%			1.50%
Variable Rate [Domain]
Debt Instrument [Line Items]
Long-term Debt		$ 498.9		$ 498.9			$ 0
Debt Instrument, Face Amount		500		500
Senior Notes, 1.7%, Due 2018 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 996.6		$ 996.6			$ 0
Debt Instrument, Interest Rate, Stated Percentage		1.70%		1.70%			1.70%
Debt Instrument, Face Amount		$ 1,000		$ 1,000
Senior Notes, 1.9%, Due 2019 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 1,641.2		$ 1,641.2			$ 0
Debt Instrument, Interest Rate, Stated Percentage		1.90%		1.90%			1.90%
Debt Instrument, Face Amount		$ 1,700		$ 1,700
Senior Notes, 2.2%, Due 2019 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 373.4		$ 373.4			$ 372.9
Debt Instrument, Interest Rate, Stated Percentage		2.20%		2.20%			2.20%
Senior Notes, 3.95%, Due 2020 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 744.4		$ 744.4			$ 743.4
Debt Instrument, Interest Rate, Stated Percentage		3.95%		3.95%			3.95%
Senior Notes, 2.4%, Due 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 1,838.3		$ 1,838.3			$ 0
Debt Instrument, Interest Rate, Stated Percentage		2.40%		2.40%			2.40%
Debt Instrument, Face Amount		$ 1,900		$ 1,900
Senior Notes, 5.45%, Due 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 664.6		$ 664.6			$ 674.9
Debt Instrument, Interest Rate, Stated Percentage		5.45%		5.45%			5.45%
Senior Notes, 4.125%, Due 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 494.9		$ 494.9			$ 494.1
Debt Instrument, Interest Rate, Stated Percentage		4.125%		4.125%			4.125%
Senior Notes, 2.75%, Due 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 985		$ 985			$ 983.1
Debt Instrument, Interest Rate, Stated Percentage		2.75%		2.75%			2.75%
Senior Notes, 2.8%, Due 2023 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 1,289.6		$ 1,289.6			$ 0
Debt Instrument, Interest Rate, Stated Percentage		2.80%		2.80%			2.80%
Debt Instrument, Face Amount		$ 1,300		$ 1,300
Senior notes, 3.5%, due 2024 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 742.3		$ 742.3			$ 741.6
Debt Instrument, Interest Rate, Stated Percentage		3.50%		3.50%			3.50%
Senior notes, 3.2%, due 2026 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 2,770.4		$ 2,770.4			$ 0
Debt Instrument, Interest Rate, Stated Percentage		3.20%		3.20%			3.20%
Debt Instrument, Face Amount		$ 2,800		$ 2,800
Senior notes, 4.25%, due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 1,480		$ 1,480			$ 0
Debt Instrument, Interest Rate, Stated Percentage		4.25%		4.25%			4.25%
Debt Instrument, Face Amount		$ 1,500		$ 1,500
Senior Notes, 6.625%, Due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 765.1		$ 765.1			$ 765
Debt Instrument, Interest Rate, Stated Percentage		6.625%		6.625%			6.625%
Senior Notes, 6.75%, Due 2037 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 527.3		$ 527.3			$ 527
Debt Instrument, Interest Rate, Stated Percentage		6.75%		6.75%			6.75%
Senior Notes, 4.5%, Due 2042 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 477.7		$ 477.7			$ 477.1
Debt Instrument, Interest Rate, Stated Percentage		4.50%		4.50%			4.50%
Senior Notes, 4.125%, Due 2042 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 489		$ 489			$ 488.6
Debt Instrument, Interest Rate, Stated Percentage		4.125%		4.125%			4.125%
Senior Notes, 4.75%, Due 2044 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 370.6		$ 370.6			$ 370.5
Debt Instrument, Interest Rate, Stated Percentage		4.75%		4.75%			4.75%
Senior Notes, 4.375%, Due 2046 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 2,375.3		$ 2,375.3			$ 0
Debt Instrument, Interest Rate, Stated Percentage		4.375%		4.375%			4.375%
Debt Instrument, Face Amount		$ 2,400		$ 2,400
Debt Issued for Humana Acquisition [Domain]
Debt Instrument [Line Items]
Long-term Debt		10,200		10,200
Debt Instrument, Face Amount		13,000		$ 13,000
Debt Instrument, Redemption Price, Percentage				101.00%
2015 and 2016 Cash Flow Hedges [Domain]
Debt Instrument [Line Items]
Derivative, Notional Amount		3,500		$ 3,500
Derivative, Counterparty Payment		51
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net				51
Terminated Swaps [Domain]
Debt Instrument [Line Items]
Derivative, Notional Amount		2,300		2,300		$ 3,500
Derivative, Counterparty Payment				193
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net				193
Treasury Lock [Member]
Debt Instrument [Line Items]
Derivative, Notional Amount		2,300		2,300
March 2014 Cash Flow Hedge [Domain]
Debt Instrument [Line Items]
Derivative, Notional Amount		500		500
Derivative, Counterparty Payment		103
Loss on Cash Flow Hedge Ineffectiveness		2	$ 4
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net		25			$ 73
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Unamortized Debt Issuance Expense		$ 1.1		1.1			$ 2
Line of Credit Facility, Maximum Amount Outstanding During Period				$ 0	$ 0
[1]	At September 30, 2016, our 5.95% senior notes due March 2017 and 1.75% senior notes due May 2017 are each classified as current in our consolidated balance sheet.

Debt - Line of Credit (Details)

Debt - Line of Credit (Details) $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)
Line of Credit Facility [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount	$ 2,000
Additional Credit Facility	500
Maximum Amount Of Letters Of Credit Issuable	$ 200
Facility fee (in hundredths)	0.10%
Minimum [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount	$ 2,000
Level the debt to capitalization must be below under the facility agreement	50.00%
Minimum [Member] | Line of Credit [Member]
Line of Credit Facility [Line Items]
Facility fee (in hundredths)	0.05%
Maximum [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount	$ 3,000
Maximum [Member] | Line of Credit [Member]
Line of Credit Facility [Line Items]
Facility fee (in hundredths)	0.15%
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Amount Outstanding During Period	$ 0	$ 0
Unsecured revolving credit agreement	1,500
Bridge Loan [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Amount Outstanding During Period	0
Expected Proceeds From Issuance Of Long Term Debt	$ 13,000
Term Loan [Member]
Line of Credit Facility [Line Items]
Interest Rate On Term Loan Agreement Federal Funds	0.50%
Interest Rate On Term Loan Agreement Libor	1.00%
Term Loan Principal	$ 3,200
Level the debt to capitalization must be at or below under the term loan agreement	0.5
Term Loan [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Amount Outstanding During Period	$ 0
LIBOR Margins	0.75%
Base Rate Margins	0.00%
Term Loan [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
LIBOR Margins	1.50%
Base Rate Margins	0.50%

Capital Stock - Repurchases (De

Capital Stock - Repurchases (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount			$ 1,000	$ 1,000
Stock Repurchased During Period, Value	$ 0	$ 296.3
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 1,100

Capital Stock - Dividends (Deta

Capital Stock - Dividends (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016
Dividends Amount Per Share	$ 0.25	$ 0.25	$ 0.25
Dividends	$ 87.7	$ 87.7	$ 87.6
Maximum Amount of Dividends Declared [Domain]
Dividends Amount Per Share	$ 0.25

Capital Stock - Stock Units (De

Capital Stock - Stock Units (Details) - $ / shares shares in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
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%
Performance Shares [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	0.3
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	0.9
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	2.2
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	100.00%
Estimated Fair Market Value (per unit)	$ 34.33	$ 32.13
Expected Term (in years)	7 years 40 days	6 years 175 days
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Weighted Average Volatility Rate	32.90%	33.40%
Risk Free Interest Rate	1.52%	1.81%
Dividend Yield	0.91%	1.13%
Initial Price	$ 103.45	$ 100.50

Dividend Restrictions and Sta64

Dividend Restrictions and Statutory Surplus (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Dividend Restrictions and Statutory Surplus [Line Items]
Dividends Amount Per Share	$ 0.25	$ 0.25	$ 0.25
Insurance and HMO [Member]
Dividend Restrictions and Statutory Surplus [Line Items]
Dividends available	$ 396
Proceeds from dividends received	320
Statutory capital and surplus	$ 10,100			$ 9,900
Maximum Amount of Dividends Declared [Domain]
Dividend Restrictions and Statutory Surplus [Line Items]
Dividends Amount Per Share	$ 0.25

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	6 Months Ended	9 Months Ended	12 Months Ended
	Jun. 30, 2014	Sep. 30, 2016	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2015
Loss Contingencies [Line Items]
Long-term Debt		$ 20,663.3			$ 7,787.4
Loss on Contract Termination		1,000
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
Debt Issued for Humana Acquisition [Domain]
Loss Contingencies [Line Items]
Long-term Debt		$ 10,200
Debt Instrument, Redemption Price, Percentage		101.00%

Segment Information (Details)

Segment Information (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Litigation-related proceeds, net of tax					$ (71.3)
Litigation Settlement, Amount		$ 0	$ 0	$ 0	(109.6)
Segment Reporting Information, Profit (Loss) [Abstract]
Revenue from external customers		15,528.3	14,772.8	46,654.6	44,617.4
Operating Earnings	[1],[2]	734.3	668.6	2,338.7	2,235
Health Care [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenue from external customers		14,949.9	14,202.3	44,932.6	42,904.9
Operating Earnings	[2]	752.5	675.4	2,365.8	2,219
Group Insurance [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenue from external customers		563.7	557.5	1,683.1	1,677.6
Operating Earnings	[2]	19.1	25.6	90.3	114.3
Large Case Pension [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenue from external customers		14.7	13	38.9	34.9
Operating Earnings	[2]	5	4.4	9.1	12.7
Corporate Financing [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenue from external customers		0	0	0	0
Operating Earnings	[2]	$ (42.3)	$ (36.8)	$ (126.5)	$ (111)
[1]	In addition to net realized capital losses and gains 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 during the three and nine months ended September 30, 2016 and 2015 related to the acquisitions of Coventry and bswift LLC (“bswift”) and the Humana Acquisition. 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, as well as the cost of the Bridge Credit Agreement and the Term Loan Agreement executed in connection with the Humana Acquisition, which are reflected in our GAAP Consolidated Statements of Income in interest expense. Transaction costs also include the negative cost of carry associated with the 2016 Humana-related senior notes. Prior to the closing of the Humana Acquisition, the negative cost of carry associated with the 2016 Humana-related senior notes is excluded from operating earnings. The components of the negative cost of carry are reflected in our GAAP Consolidated Statements of Income in interest expense and net investment income. On and after the closing of the Humana Acquisition, the interest expense and net investment income associated with the 2016 Humana-related senior notes no longer will be excluded from operating earnings.•In 1993, we discontinued the sale of our fully guaranteed large case pensions products and established a reserve for anticipated future losses on these products, which we review quarterly. During the nine months ended September 30, 2016, we reduced the reserve for anticipated future losses on discontinued products. We believe excluding any changes in the reserve for anticipated future losses on discontinued products from operating earnings provides more useful information as to our continuing products and is consistent with the treatment of the operating results of these discontinued products, which are credited or charged to the reserve and do not affect our operating results. Refer to Note 18 for additional information on the reduction of the reserve for anticipated future losses on discontinued products.•In the nine months ended September 30, 2015, we received proceeds, net of legal costs, in connection with a litigation settlement. These net proceeds were recorded in fees and other revenue in our GAAP Consolidated Statements of Income. •The corresponding tax benefit or expense related to the items excluded from operating earnings discussed above. The tax benefit or expense was calculated utilizing the appropriate tax rate for each individual item excluded from operating earnings.
[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 - Reconcili

Segment Information - Reconciliation of Operating Earnings (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reconciliation [Abstract]
Net income attributable to Aetna		$ 603.9	$ 560.1	$ 2,131.6	$ 2,069.4
Transaction and integration-related costs		164	62.3	333.1	138.6
Reduction of reserve for anticipated future losses on discontinued products		0	0	(128.5)	0
Litigation Settlement, Amount		0	0	0	(109.6)
Amortization of Intangible Assets		61.4	65.1	187	192
Net Realized Capital Gains (Losses), Other Item		(34.8)	33.1	(85.5)	23
Income tax expense (benefit)		(60.2)	(52)	(99)	(78.4)
Operating Earnings	[1],[2]	$ 734.3	$ 668.6	$ 2,338.7	$ 2,235
[1]	In addition to net realized capital losses and gains 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 during the three and nine months ended September 30, 2016 and 2015 related to the acquisitions of Coventry and bswift LLC (“bswift”) and the Humana Acquisition. 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, as well as the cost of the Bridge Credit Agreement and the Term Loan Agreement executed in connection with the Humana Acquisition, which are reflected in our GAAP Consolidated Statements of Income in interest expense. Transaction costs also include the negative cost of carry associated with the 2016 Humana-related senior notes. Prior to the closing of the Humana Acquisition, the negative cost of carry associated with the 2016 Humana-related senior notes is excluded from operating earnings. The components of the negative cost of carry are reflected in our GAAP Consolidated Statements of Income in interest expense and net investment income. On and after the closing of the Humana Acquisition, the interest expense and net investment income associated with the 2016 Humana-related senior notes no longer will be excluded from operating earnings.•In 1993, we discontinued the sale of our fully guaranteed large case pensions products and established a reserve for anticipated future losses on these products, which we review quarterly. During the nine months ended September 30, 2016, we reduced the reserve for anticipated future losses on discontinued products. We believe excluding any changes in the reserve for anticipated future losses on discontinued products from operating earnings provides more useful information as to our continuing products and is consistent with the treatment of the operating results of these discontinued products, which are credited or charged to the reserve and do not affect our operating results. Refer to Note 18 for additional information on the reduction of the reserve for anticipated future losses on discontinued products.•In the nine months ended September 30, 2015, we received proceeds, net of legal costs, in connection with a litigation settlement. These net proceeds were recorded in fees and other revenue in our GAAP Consolidated Statements of Income. •The corresponding tax benefit or expense related to the items excluded from operating earnings discussed above. The tax benefit or expense was calculated utilizing the appropriate tax rate for each individual item excluded from operating earnings.
[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) $ in Millions	Sep. 30, 2016USD ($)
Reinsurance Disclosures [Abstract]
Collateralized excess of loss on resinsurance coverage	$ 200

Discontinued Products (Details)

Discontinued Products (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2016		Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015	Sep. 30, 2016		Dec. 31, 2015
Reserve For Discontinued Products [Roll Forward]
Reduction of reserve for anticipated future losses on discontinued products		$ 0		$ 0	$ (128.5)		$ 0
Assets:
Investments								$ 25,738.3		$ 24,679.6
Total assets								71,882.6		53,381.5
Liabilities:
Future policy benefits								5,992.9		6,268.2
Total liabilities								53,538.1		37,202.9
Discontinued Products [Member]
Reserve For Discontinued Products [Roll Forward]
Reserve, beginning of period					1,067.2	[1]	1,014.7
Operating income (loss)					(19.9)		(2.1)
Net realized capital gains					49.5		57.2
Reserve, end of period		968.3	[1]	1,069.8	968.3	[1]	1,069.8
Assets:
Investments	[1]							3,119.1		3,059.1
Other Assets	[1]							87.1		128.9
Current And Deferred Income Taxes	[1]							0		20.5
Receivable from continuing products	[1],[2]							545.2		602
Total assets	[1]							3,751.4		3,810.5
Liabilities:
Future policy benefits	[1]							2,373		2,493.5
Reserve for anticipated future losses on discontinued products		968.3	[1]	1,069.8	1,067.2	[1]	1,014.7	968.3	[1]	1,067.2	[1]
Current And Deferred Income Tax Liabilities	[1]							43.1		0
Other Liabilities	[1],[3]							367		249.8
Total liabilities	[1]							3,751.4		3,810.5
Scheduled Contract Maturities, Settlements And Benefit Payments		85		$ 89	$ 265		$ 269
Debt And Equity Securities Available For Sale [Member]
Assets:
Investments								22,560.6		21,323
Debt And Equity Securities Available For Sale [Member] | Discontinued Products [Member]
Assets:
Investments	[1]							2,082.5		2,019.6
Mortgage Loans [Member]
Assets:
Investments								1,518.5		1,553.7
Mortgage Loans [Member] | Discontinued Products [Member]
Assets:
Investments	[1]							378.5		396
Other Investments [Member]
Assets:
Investments								1,659.2		1,802.9
Other Investments [Member] | Discontinued Products [Member]
Assets:
Investments	[1]							$ 658.1		$ 643.5
After Income Tax Expense (Benefit) [Member]
Reserve For Discontinued Products [Roll Forward]
Reduction of reserve for anticipated future losses on discontinued products		84
Before Income Tax Expense (Benefit) [Member]
Reserve For Discontinued Products [Roll Forward]
Reduction of reserve for anticipated future losses on discontinued products		$ 129
[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.