Benefit Expenses Excluded From Activity in Benefits Payable (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Military services	$ 11	$ (27)	$ 908
Future policy benefits	32	354	136
Total	$ 43	$ 327	$ 1,044

Amount of expense (income) recognized due to changes in the accrued obligation to policyholders that relates to insured events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Financial Reporting Release (FRR)

-Number 403

-Paragraph 04

-Subparagraph b

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 40

-Section 50

-Paragraph 3

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6482485&loc=d3e14764-158437

Name:	us-gaap_LiabilityForFuturePolicyBenefitsPeriodExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration