Schedule II - Condensed Statements Of Cash Flows (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fees and reimbursements received	$ 281	$ 397	$ 533
Investment income received	594	898	997
Operating expenses paid	(400)	(312)	(274)
Interest paid, net of interest converted to principal	(400)	(479)	(574)
Income taxes (paid) received	(6)	74	414
Net cash provided (used) by operating activities	(1,027)	(2,627)	(946)
Purchase of fixed-maturity securities	(4,463)	(7,744)	(9,967)
Sale and redemption of fixed-maturity securities	6,873	11,321	11,896
Sale (purchase) of short-term investments, net	1,012	680	662
Sale (purchase) of other investments, net	114	73	53
(Payments) proceeds for derivative settlements	(288)	(373)	(216)
Collateral (to) from swap counterparty	(285)		166
Net cash provided (used) by investing activities	4,195	4,007	4,778
Proceeds from investment agreements	36	71	45
Payments for drawdowns of investment agreements	(688)	(524)	(767)
Payments for securities sold under agreements to repurchase	(287)	(184)	(31)
Payments for retirement of debt	(540)	(65)	(393)
Purchase of treasury stock		(50)	(31)
Restricted stock awards settlements, net	1	(2)	2
Net cash provided (used) by financing activities	(2,811)	(1,877)	(3,505)
Net increase (decrease) in cash and cash equivalents	357	(497)	327
Cash and cash equivalents-beginning of period	633	1,130	803
Cash and cash equivalents-end of period	990	633	1,130
Net income (loss)	1,234	(1,319)	53
Current income taxes	(5)	86	501
Net investment losses related to other-than-temporary impairments	105	101	64
Net (gains) losses on financial instruments at fair value and foreign exchange	(73)	40	(430)
Other net realized (gains) losses	(7)	(262)	47
Deferred income tax benefit	365	(935)	(221)
Other operating	257	408	265
Total adjustments to net income (loss)	(2,261)	(1,308)	(999)
Net cash provided (used) by operating activities	(1,027)	(2,627)	(946)
Parent Company [Member]
Fees and reimbursements received	5	31
Investment income received	118	89	145
Operating expenses paid	(43)	(30)	(28)
Interest paid, net of interest converted to principal	(101)	(107)	(115)
Income taxes (paid) received	224	353	149
Net cash provided (used) by operating activities	203	336	151
Purchase of fixed-maturity securities	(1,017)	(3,737)	(6,259)
Sale and redemption of fixed-maturity securities	2,370	4,651	7,288
Sale (purchase) of short-term investments, net	375	251	363
Sale (purchase) of other investments, net	107	81	55
(Payments) proceeds for derivative settlements	(207)	(85)	16
Collateral (to) from swap counterparty	(285)		166
Contributions to subsidiaries	(12)		(35)
Advances to subsidiaries, net	1	(19)	(21)
Net cash provided (used) by investing activities	1,332	1,142	1,573
Proceeds from investment agreements	31	65	39
Payments for drawdowns of investment agreements	(679)	(500)	(735)
Payments for securities sold under agreements to repurchase	(639)	(835)	(618)
Payments for retirement of debt	(180)	(70)	(43)
Payments for affiliate loans	(109)	(37)	(405)
Purchase of treasury stock		(50)	(30)
Restricted stock awards settlements, net	1	(2)	2
Net cash provided (used) by financing activities	(1,575)	(1,429)	(1,790)
Net increase (decrease) in cash and cash equivalents	(40)	49	(66)
Cash and cash equivalents-beginning of period	132	83	149
Cash and cash equivalents-end of period	92	132	83
Net income (loss)	1,234	(1,376)	(3)
Intercompany accounts receivable	(9)	(10)	41
Current income taxes	57	124	56
Equity in earnings of subsidiaries	(762)	1,233	(99)
Dividends from subsidiaries	60	46	19
Net investment losses related to other-than-temporary impairments	59	33	59
Net (gains) losses on financial instruments at fair value and foreign exchange	119	278	117
Other net realized (gains) losses	(6)	17	(1)
Deferred income tax benefit	(613)	(85)	(90)
(Gains) losses on extinguishment of debt	2		1
Other operating	62	76	51
Total adjustments to net income (loss)	(1,031)	1,712	154
Net cash provided (used) by operating activities	$ 203	$ 336	$ 151