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Stockholders' Equity - Additional Information (Detail) - USD ($) |  |  | 3 Months Ended | 5 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Mar. 13, 2015 | Nov. 10, 2014 | Mar. 31, 2016 | Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Mar. 13, 2015 | Jul. 03, 2015 | Aug. 31, 2014
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |
Cash dividend per share |  |  | $ 0.29 | $ 0.29 | $ 0.29 | $ 0.29 | $ 0.28 | $ 0.28 |  |  |
Share repurchase authorization |  |  |  |  |  |  |  |  |  |  | $ 1,000,000,000
Remaining authorized amount |  |  |  |  |  |  |  |  |  |  | $ 816,000,000
Common shares acquired in connection with employee stock plans, shares |  |  | 430,000 |  |  |  | 250,000 |  |  |  |
Common shares acquired in connection with employee stock plans, amount |  |  | $ 71,000,000 |  |  |  | $ 40,000,000 |  |  |  |
Treasury stock reissued (shares) |  |  | 1,150,000 |  |  |  |  |  |  |  |
Treasury stock reissued |  |  | $ 76,000,000 |  |  |  |  |  |  |  |
Accumulated other comprehensive income |  |  | 76,000,000 | $ 58,000,000 |  |  |  |  |  |  |
Net unrealized gains on our investment securities |  |  |  |  |  |  |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |
Accumulated other comprehensive income |  |  | 144,000,000 | 58,000,000 |  |  |  |  |  |  |
Additional liability that would exist on closed block of long-term care policies assuming unrealized gains on investments backing such products were realized and reinvested at current yields |  |  |  |  |  |  |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |
Accumulated other comprehensive income |  |  | $ 68,000,000 | $ 0 |  |  |  |  |  |  |
September 2014 Share Repurchase Authorization |  |  |  |  |  |  |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |
Share repurchase authorization |  |  |  |  |  |  | 2,000,000,000 |  |  |  |
Remaining authorized amount |  |  |  |  |  |  |  |  |  | $ 1,040,000,000 |
Expiration date of new authorization |  |  | Dec. 31, 2016 |  |  |  |  |  |  |  |
Value of shares repurchased |  |  |  |  |  |  | $ 26,000,000 |  |  |  |
Shares repurchased in open market |  |  | 0 |  |  |  | 150,000 |  |  |  |
Accelerated Share Repurchase Agreement |  |  |  |  |  |  |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |
Share repurchase authorization |  | $ 500,000,000 |  |  |  |  |  |  |  |  |
Value of shares repurchased |  | $ 400,000,000 |  |  |  |  |  |  | $ 500,000,000 |  |
Shares repurchased in open market |  | 3,060,000 |  |  |  |  |  |  | 3,420,000 |  |
Decrease in capital in excess of par value |  | $ 100,000,000 |  |  |  |  |  |  |  |  |
ASR, shares received | 360,000 |  |  |  |  |  |  |  |  |  |
Shares repurchased in open market, average price |  |  |  |  |  |  |  |  | $ 146.21 |  |

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- Definition Number of shares of common stock that were repurchased in the administration of our employee share-based compensation plans. Under the terms of these plans, we accept shares of common stock from option holders if they elect to surrender previously-owned shares upon exercise of the option to cover the exercise price of the options or, in the case of restricted shares of common stock, the withholding of shares to satisfy tax withholding obligations associated with the vesting of such shares. + References No definition available. + Details
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- Definition Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e637-108580 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e681-108580 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=66004124&loc=SL7669686-108580 + Details
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- Definition Number of treasury shares (units) reissued during the period, excluding reissuance of shares (units) held in treasury used to satisfy equity-based compensation obligations exercised by the holders of such rights. Upon reissuance of shares (units) from treasury, either the common or preferred stock (unit) reissued is outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 + Details
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