Income Taxes (Income Taxes and Shareholders' Equity) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current taxes:
Federal	$ 0	$ 3	$ (1)
State	8	2	1
Foreign	1	(6)	15
Deferred taxes:
Federal	165	350	(919)
Foreign	(8)	15	(16)
Provision (benefit) for income taxes	166	364	(920)
Income tax effects allocated directly to equity [Abstract]
Change in unrealized gains and losses on investments	(81)	86	116
Change in other-than-temporary impairment losses	4	42	9
Change in foreign currency translation	1	(2)	(1)
Share-based compensation	4	7	4
Total income taxes charged (credited) to shareholders' equity	(72)	133	128
Total effect of income taxes	$ 94	$ 497	$ (792)