Claim and Claim Adjustment Expense Reserves - Impact of Loss Portfolio Transfer on Consolidated Statements of Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Insurance [Abstract]
Net A&EP adverse development before consideration of LPT	$ 150		$ 363
Provision for uncollectible third party reinsurance on A&EP			140
Additional amounts ceded under LPT	150		503
Retroactive reinsurance benefit recognized	(85)	$ (13)	(314)
Pretax impact of deferred retroactive reinsurance	$ 65	$ (13)	$ 189