Assets Measured at Fair Value on Recurring Basis and Utilized Significant Unobservable (Level 3) Inputs to Determine Fair Value (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 5,871		$ 6,162		$ 4,830
Total realized and unrealized gains (losses), Included in net income (loss)	33		(27)		(38)
Total realized and unrealized gains (losses), Included in OCI	62		(22)		272
Purchases	847		561		978
Sales	(260)		(305)		(395)
Issuances	3		3		19
Settlements	(684)		(783)		(672)
Transfer into Level 3	644		577		1,908
Transfer out of Level 3	(455)		(295)		(740)
Ending balance	6,061		5,871		6,162
Total gains (losses) included in net income (loss) attributable to assets still held	16		(34)		(19)
Restricted other invested assets related to securitization entities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	211	[1]	194	[1]	176	[1]
Total realized and unrealized gains (losses), Included in net income (loss)	19	[1]	(1)	[1]	18	[1]
Total realized and unrealized gains (losses), Included in OCI	0	[1]	0	[1]	0	[1]
Purchases	0	[1]	19	[1]	100	[1]
Sales	0	[1]	0	[1]	(100)	[1]
Issuances	0	[1]	0	[1]	0	[1]
Settlements	0	[1]	(20)	[1]	0	[1]
Transfer into Level 3	0	[1]	19	[1]	0	[1]
Transfer out of Level 3	0	[1]	0	[1]	0	[1]
Ending balance	230	[1]	211	[1]	194	[1]
Total gains (losses) included in net income (loss) attributable to assets still held	18	[1]	(1)	[1]	13	[1]
Reinsurance recoverable
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	(1)	[2]	10	[2]	16	[2]
Total realized and unrealized gains (losses), Included in net income (loss)	11	[2]	(14)	[2]	(9)	[2]
Total realized and unrealized gains (losses), Included in OCI	0	[2]	0	[2]	0	[2]
Purchases	0	[2]	0	[2]	0	[2]
Sales	0	[2]	0	[2]	0	[2]
Issuances	3	[2]	3	[2]	3	[2]
Settlements	0	[2]	0	[2]	0	[2]
Transfer into Level 3	0	[2]	0	[2]	0	[2]
Transfer out of Level 3	0	[2]	0	[2]	0	[2]
Ending balance	13	[2]	(1)	[2]	10	[2]
Total gains (losses) included in net income (loss) attributable to assets still held	11	[2]	(14)	[2]	(9)	[2]
Other assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance			9	[3]	0	[3]
Total realized and unrealized gains (losses), Included in net income (loss)			0	[3]	(7)	[3]
Total realized and unrealized gains (losses), Included in OCI			0	[3]	0	[3]
Purchases			0	[3]	0	[3]
Sales			0	[3]	0	[3]
Issuances			0	[3]	16	[3]
Settlements			(9)	[3]	0	[3]
Transfer into Level 3			0	[3]	0	[3]
Transfer out of Level 3			0	[3]	0	[3]
Ending balance			0	[3]	9	[3]
Total gains (losses) included in net income (loss) attributable to assets still held			0	[3]	(7)	[3]
Fixed maturity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	5,524		5,740		4,223
Total realized and unrealized gains (losses), Included in net income (loss)	36		12		4
Total realized and unrealized gains (losses), Included in OCI	62		(22)		274
Purchases	810		498		786
Sales	(221)		(241)		(215)
Issuances	0		0		0
Settlements	(674)		(726)		(528)
Transfer into Level 3	644		558		1,904
Transfer out of Level 3	(417)		(295)		(708)
Ending balance	5,764		5,524		5,740
Total gains (losses) included in net income (loss) attributable to assets still held	15		15		10
Fixed maturity securities | U.S. government, agencies and government-sponsored enterprises
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	5		9		13
Total realized and unrealized gains (losses), Included in net income (loss)	0		0		0
Total realized and unrealized gains (losses), Included in OCI	0		0		0
Purchases	0		0		0
Sales	0		0		0
Issuances	0		0		0
Settlements	(1)		(4)		0
Transfer into Level 3	0		0		9
Transfer out of Level 3	0		0		(13)
Ending balance	4		5		9
Total gains (losses) included in net income (loss) attributable to assets still held	0		0		0
Fixed maturity securities | Government - non-U.S.
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	23		9		10
Total realized and unrealized gains (losses), Included in net income (loss)	0		0		0
Total realized and unrealized gains (losses), Included in OCI	0		1		0
Purchases	3		0		0
Sales	0		0		0
Issuances	0		0		0
Settlements	(2)		(3)		(1)
Transfer into Level 3	0		16		0
Transfer out of Level 3	(17)		0		0
Ending balance	7		23		9
Total gains (losses) included in net income (loss) attributable to assets still held	0		0		0
Fixed maturity securities | U.S. corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	2,400	[4]	2,683	[4],[5]	2,511	[5]
Total realized and unrealized gains (losses), Included in net income (loss)	27	[4]	18	[4]	12	[5]
Total realized and unrealized gains (losses), Included in OCI	57	[4]	(15)	[4]	118	[5]
Purchases	211	[4]	178	[4]	147	[5]
Sales	(60)	[4]	(151)	[4]	(122)	[5]
Issuances	0	[4]	0	[4]	0	[5]
Settlements	(253)	[4]	(349)	[4]	(214)	[5]
Transfer into Level 3	272	[4]	195	[4]	726	[5]
Transfer out of Level 3	(206)	[4]	(159)	[4]	(495)	[5]
Ending balance	2,448	[4]	2,400	[4]	2,683	[4],[5]
Total gains (losses) included in net income (loss) attributable to assets still held	12	[4]	13	[4]	14	[5]
Fixed maturity securities | Corporate - non-U.S.
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	1,819	[4]	1,983	[4],[5]	1,284	[5]
Total realized and unrealized gains (losses), Included in net income (loss)	4		4	[4]	3	[5]
Total realized and unrealized gains (losses), Included in OCI	9		(24)	[4]	92	[5]
Purchases	282		120	[4]	269	[5]
Sales	(123)		(33)	[4]	(29)	[5]
Issuances	0		0	[4]	0	[5]
Settlements	(222)		(220)	[4]	(186)	[5]
Transfer into Level 3	97		76	[4]	711	[5]
Transfer out of Level 3	(61)		(87)	[4]	(161)	[5]
Ending balance	1,805		1,819	[4]	1,983	[4],[5]
Total gains (losses) included in net income (loss) attributable to assets still held	2		2	[4]	2	[5]
Fixed maturity securities | Residential mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	105		157	[5]	95	[5]
Total realized and unrealized gains (losses), Included in net income (loss)	0		(9)		(7)	[5]
Total realized and unrealized gains (losses), Included in OCI	(3)		7		14	[5]
Purchases	16		0		20	[5]
Sales	(23)		(8)		(17)	[5]
Issuances	0		0		0	[5]
Settlements	(13)		(29)		(31)	[5]
Transfer into Level 3	24		14		86	[5]
Transfer out of Level 3	(31)		(27)		(3)	[5]
Ending balance	75		105		157	[5]
Total gains (losses) included in net income (loss) attributable to assets still held	0		0		(7)	[5]
Fixed maturity securities | Commercial mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	6		35		39
Total realized and unrealized gains (losses), Included in net income (loss)	0		(5)		(2)
Total realized and unrealized gains (losses), Included in OCI	2		(1)		5
Purchases	0		0		0
Sales	0		0		(1)
Issuances	0		0		0
Settlements	(2)		(32)		(2)
Transfer into Level 3	7		11		3
Transfer out of Level 3	(8)		(2)		(7)
Ending balance	5		6		35
Total gains (losses) included in net income (loss) attributable to assets still held	0		(4)		(1)
Fixed maturity securities | Other asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	1,166	[4]	864	[4],[5]	271	[5]
Total realized and unrealized gains (losses), Included in net income (loss)	5	[4]	4	[4]	(2)	[5]
Total realized and unrealized gains (losses), Included in OCI	(3)	[4]	10	[4]	45	[5]
Purchases	298	[4]	200	[4]	350	[5]
Sales	(15)	[4]	(49)	[4]	(46)	[5]
Issuances	0	[4]	0	[4]	0	[5]
Settlements	(181)	[4]	(89)	[4]	(94)	[5]
Transfer into Level 3	244	[4]	246	[4]	369	[5]
Transfer out of Level 3	(94)	[4]	(20)	[4]	(29)	[5]
Ending balance	1,420	[4]	1,166	[4]	864	[4],[5]
Total gains (losses) included in net income (loss) attributable to assets still held	1	[4]	4	[4]	2	[5]
Equity Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	78		99		98
Total realized and unrealized gains (losses), Included in net income (loss)	0		2		1
Total realized and unrealized gains (losses), Included in OCI	0		0		(2)
Purchases	1		1		10
Sales	(38)		(24)		(8)
Issuances	0		0		0
Settlements	0		0		0
Transfer into Level 3	0		0		0
Transfer out of Level 3	(7)		0		0
Ending balance	34		78		99
Total gains (losses) included in net income (loss) attributable to assets still held	0		0		0
Other invested assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	59		110		317
Total realized and unrealized gains (losses), Included in net income (loss)	(33)		(26)		(45)
Total realized and unrealized gains (losses), Included in OCI	0		0		0
Purchases	36		43		82
Sales	(1)		(40)		(72)
Issuances	0		0		0
Settlements	(10)		(28)		(144)
Transfer into Level 3	0		0		4
Transfer out of Level 3	(31)		0		(32)
Ending balance	20		59		110
Total gains (losses) included in net income (loss) attributable to assets still held	(28)		(34)		(26)
Other invested assets | Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	25		34		53
Total realized and unrealized gains (losses), Included in net income (loss)	(33)		(33)		(58)
Total realized and unrealized gains (losses), Included in OCI	0		0		0
Purchases	36		43		58
Sales	(1)		0		0
Issuances	0		0		0
Settlements	(7)		(19)		(19)
Transfer into Level 3	0		0		0
Transfer out of Level 3	0		0		0
Ending balance	20		25		34
Total gains (losses) included in net income (loss) attributable to assets still held	(28)		(36)		(41)
Other invested assets | Trading Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	34		76		264
Total realized and unrealized gains (losses), Included in net income (loss)	0		7		13
Total realized and unrealized gains (losses), Included in OCI	0		0		0
Purchases	0		0		24
Sales	0		(40)		(72)
Issuances	0		0		0
Settlements	(3)		(9)		(125)
Transfer into Level 3	0		0		4
Transfer out of Level 3	(31)		0		(32)
Ending balance	0		34		76
Total gains (losses) included in net income (loss) attributable to assets still held	0		2		15
Other invested assets | Credit default swaps | Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	10		7		0
Total realized and unrealized gains (losses), Included in net income (loss)	0		12		12
Total realized and unrealized gains (losses), Included in OCI	0		0		0
Purchases	0		0		0
Sales	0		0		0
Issuances	0		0		0
Settlements	(7)		(9)		(5)
Transfer into Level 3	0		0		0
Transfer out of Level 3	0		0		0
Ending balance	3		10		7
Total gains (losses) included in net income (loss) attributable to assets still held	0		6		12
Other invested assets | Equity index options | Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	12		25		39
Total realized and unrealized gains (losses), Included in net income (loss)	(31)		(43)		(59)
Total realized and unrealized gains (losses), Included in OCI	0		0		0
Purchases	36		39		55
Sales	0		0		0
Issuances	0		0		0
Settlements	0		(9)		(10)
Transfer into Level 3	0		0		0
Transfer out of Level 3	0		0		0
Ending balance	17		12		25
Total gains (losses) included in net income (loss) attributable to assets still held	(28)		(40)		(42)
Other invested assets | Other foreign currency contracts | Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	3		0		9
Total realized and unrealized gains (losses), Included in net income (loss)	(2)		(1)		(11)
Total realized and unrealized gains (losses), Included in OCI	0		0		0
Purchases	0		4		3
Sales	(1)		0		0
Issuances	0		0		0
Settlements	0		0		(1)
Transfer into Level 3	0		0		0
Transfer out of Level 3	0		0		0
Ending balance	0		3		0
Total gains (losses) included in net income (loss) attributable to assets still held	0		(1)		(11)
Other invested assets | Interest rate swaps | Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance			2		5
Total realized and unrealized gains (losses), Included in net income (loss)			(1)		0
Total realized and unrealized gains (losses), Included in OCI			0		0
Purchases			0		0
Sales			0		0
Issuances			0		0
Settlements			(1)		(3)
Transfer into Level 3			0		0
Transfer out of Level 3			0		0
Ending balance			0		2
Total gains (losses) included in net income (loss) attributable to assets still held			$ (1)		$ 0

[1] See note 18 for additional information related to consolidated securitization entities.

[2] Represents embedded derivatives associated with the reinsured portion of our GMWB liabilities.

[3] Represents contingent receivables associated with recent business dispositions.

[4] The transfers into and out of Level 3 for fixed maturity securities were related to changes in the primary pricing source and changes in the observability of external information used in determining the fair value, such as external ratings or credit spreads.

[5] The transfers into and out of Level 3 were primarily related to private fixed rate U.S. corporate and private fixed rate corporate-non-U.S. securities and resulted from a change in the observability of the additional premium to the public bond spread to adjust for the liquidity and other features of our private placements and resulted in unobservable inputs having a significant impact on certain valuations for transfers in or no longer having significant impact on certain valuations for transfers out. During the second quarter of 2012, we began classifying private securities without an external rating as Level 3, which resulted in a significant number of securities being transferred into Level 3. The transfers into Level 3 for structured securities primarily related to securities that were recently purchased and initially classified as Level 2 based on market data that existed at the time of purchase and subsequent valuation included significant unobservable inputs.