Schedule II - Condensed Statements Of Cash Flows (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Investment income received	$ 318	$ 353	$ 419
Operating expenses paid	(136)	(130)	(238)
Interest paid, net of interest converted to principal	(139)	(169)	(179)
Income taxes (paid) received	(5)	(9)	(17)
Net cash provided (used) by operating activities	(142)	(55)	(333)
Cash flows from investing activities:
Purchases of available-for-sale investments	(2,661)	(2,146)	(1,494)
Sales of available-for-sale investments	2,412	1,145	757
Paydowns and maturities of available-for-sale investments	680	800	484
Purchases of investments at fair value	(199)	(390)	(631)
Sales, paydowns and maturities of investments at fair value	260	551	789
Sales, paydowns and maturities (purchases) of short-term investments, net	(125)	525	515
(Payments) proceeds for derivative settlements	(44)	13	(26)
Collateral (to) from swap counterparty	49	(31)	144
Other investing	(8)	47	1
Net cash provided (used) by investing activities	2,424	817	812
Cash flows from financing activities:
Proceeds from investment agreements	19	24	30
Principal paydowns of investment agreements	(85)	(116)	(192)
Principal paydowns of long-term debt	0	(11)	0
Purchases of treasury stock	(108)	(303)	(32)
Net cash provided (used) by financing activities	(2,542)	(1,014)	(892)
Effect of exchange rate changes on cash and cash equivalents	(2)	(8)	(8)
Net increase (decrease) in cash and cash equivalents	(262)	(260)	(421)
Cash and cash equivalents - beginning of year	522	782	1,258
Reclassification to assets held for sale	(73)	0	(55)
Cash and cash equivalents - end of year	187	522	782
Reconciliation of net income (loss) to net cash provided (used) by operating activities: [Abstract]
Net income (loss)	(338)	180	569
Change in: [Abstract]
Dividends from subsidiaries	118	114
Net investment losses related to other-than-temporary impairments	5	13	15
Net (gains) losses on financial instruments at fair value and foreign exchange	(84)	(105)	(128)
Other net realized (gains) losses	282	(17)	(25)
Deferred income tax provision (benefit)	(5)	107	50
Other operating	36	38	114
Total adjustments to net income (loss)	196	(235)	(902)
Net cash provided (used) by operating activities	(142)	(55)	(333)
Parent Company [Member]
Cash flows from operating activities:
Fees and reimbursements received	4	0	1
Investment income received	144	142	256
Operating expenses paid	(19)	(25)	(35)
Interest paid, net of interest converted to principal	(84)	(88)	(93)
Income taxes (paid) received	73	108	59
Net cash provided (used) by operating activities	118	137	188
Cash flows from investing activities:
Purchases of available-for-sale investments	(129)	(606)	(125)
Sales of available-for-sale investments	165	325	268
Paydowns and maturities of available-for-sale investments	90	186	98
Purchases of investments at fair value	(57)	(144)	(266)
Sales, paydowns and maturities of investments at fair value	58	171	280
Sales, paydowns and maturities (purchases) of short-term investments, net	1	232	(242)
(Payments) proceeds for derivative settlements	(37)	43	(26)
Collateral (to) from swap counterparty	52	(31)	144
Contributions to subsidiaries, net	(10)	16	(20)
Advances to subsidiaries, net	0	0	(12)
Other investing	0	24	0
Net cash provided (used) by investing activities	133	216	99
Cash flows from financing activities:
Proceeds from investment agreements	16	21	23
Principal paydowns of investment agreements	(80)	(111)	(181)
Principal paydowns of long-term debt	0	(11)	0
Payments for affiliate loans	(111)	(103)	(153)
Purchases of treasury stock	(106)	(233)	(32)
Restricted stock awards settlements	8	19	16
Net cash provided (used) by financing activities	(273)	(418)	(327)
Net increase (decrease) in cash and cash equivalents	(22)	(65)	(40)
Cash and cash equivalents - beginning of year	35	100	140
Cash and cash equivalents - end of year	13	35	100
Reconciliation of net income (loss) to net cash provided (used) by operating activities: [Abstract]
Net income (loss)	(338)	180	569
Change in: [Abstract]
Intercompany accounts receivable	(10)	(21)	(24)
Current income taxes	78	109	70
Equity in earnings of subsidiaries	262	(189)	(463)
Dividends from subsidiaries	118	116	225
Net investment losses related to other-than-temporary impairments	1	4	0
Net (gains) losses on financial instruments at fair value and foreign exchange	13	(59)	(24)
Other net realized (gains) losses	5	(21)	(1)
Deferred income tax provision (benefit)	(20)	0	(176)
(Gains) losses on extinguishment of debt	(5)	0	(1)
Other operating	14	18	13
Total adjustments to net income (loss)	456	(43)	(381)
Net cash provided (used) by operating activities	$ 118	$ 137	$ 188