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	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 5,802		$ 6,133		$ 5,871		$ 6,162
Total realized and unrealized gains (losses), Included in net income	4		1		11		(8)
Total realized and unrealized gains (losses), Included in OCI	92		(82)		129		(45)
Purchases	387		120		537		301
Sales	(127)		(83)		(155)		(242)
Issuances	1		0		2		1
Settlements	(159)		(362)		(284)		(497)
Transfer into Level 3	135		98		204		251
Transfer out of Level 3	(148)		(20)		(328)		(118)
Ending balance	5,987		5,805		5,987		5,805
Total gains (losses) included in net income attributable to assets still held	3		(2)		12		(16)
Restricted other invested assets related to securitization entities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	218		199		211		194
Total realized and unrealized gains (losses), Included in net income	6		(6)		13		(1)
Total realized and unrealized gains (losses), Included in OCI	0		0		0		0
Purchases	0		0		0		0
Sales	0		0		0		0
Issuances	0		0		0		0
Settlements	0		0		0		0
Transfer into Level 3	0		0		0		0
Transfer out of Level 3	0		0		0		0
Ending balance	224		193		224		193
Total gains (losses) included in net income attributable to assets still held	6		(6)		13		(1)
Other assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance			10	[1]			9	[1]
Total realized and unrealized gains (losses), Included in net income			(1)	[1]			0	[1]
Total realized and unrealized gains (losses), Included in OCI			0	[1]			0	[1]
Purchases			0	[1]			0	[1]
Sales			0	[1]			0	[1]
Issuances			0	[1]			0	[1]
Settlements			(9)	[1]			(9)	[1]
Transfer into Level 3			0	[1]			0	[1]
Transfer out of Level 3			0	[1]			0	[1]
Ending balance			0	[1]			0	[1]
Total gains (losses) included in net income attributable to assets still held			0	[1]			0	[1]
Reinsurance recoverable
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	2	[2]	6	[2]	(1)	[2]	10	[2]
Total realized and unrealized gains (losses), Included in net income	0	[2]	(3)	[2]	2	[2]	(8)	[2]
Total realized and unrealized gains (losses), Included in OCI	0	[2]	0	[2]	0	[2]	0	[2]
Purchases	0	[2]	0	[2]	0	[2]	0	[2]
Sales	0	[2]	0	[2]	0	[2]	0	[2]
Issuances	1	[2]	0	[2]	2	[2]	1	[2]
Settlements	0	[2]	0	[2]	0	[2]	0	[2]
Transfer into Level 3	0	[2]	0	[2]	0	[2]	0	[2]
Transfer out of Level 3	0	[2]	0	[2]	0	[2]	0	[2]
Ending balance	3	[2]	3	[2]	3	[2]	3	[2]
Total gains (losses) included in net income attributable to assets still held	0	[2]	(3)	[2]	2	[2]	(8)	[2]
Fixed maturity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	5,453		5,734		5,524		5,740
Total realized and unrealized gains (losses), Included in net income	9		7		16		6
Total realized and unrealized gains (losses), Included in OCI	92		(81)		129		(44)
Purchases	383		112		527		286
Sales	(115)		(48)		(143)		(189)
Issuances	0		0		0		0
Settlements	(157)		(334)		(277)		(464)
Transfer into Level 3	135		98		204		251
Transfer out of Level 3	(148)		(20)		(328)		(118)
Ending balance	5,652		5,468		5,652		5,468
Total gains (losses) included in net income attributable to assets still held	8		8		15		5
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	4		5		5		9
Total realized and unrealized gains (losses), Included in net income	0		0		0		0
Total realized and unrealized gains (losses), Included in OCI	0		0		0		0
Purchases	0		0		0		0
Sales	0		0		0		0
Issuances	0		0		0		0
Settlements	0		0		(1)		(4)
Transfer into Level 3	0		0		0		0
Transfer out of Level 3	0		0		0		0
Ending balance	4		5		4		5
Total gains (losses) included in net income attributable to assets still held	0		0		0		0
Fixed maturity securities | Government - non-U.S.
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	24		8		23		9
Total realized and unrealized gains (losses), Included in net income	0		0		0		0
Total realized and unrealized gains (losses), Included in OCI	0		0		0		0
Purchases	1		0		3		0
Sales	0		0		0		0
Issuances	0		0		0		0
Settlements	0		0		(1)		(1)
Transfer into Level 3	0		0		0		0
Transfer out of Level 3	0		0		0		0
Ending balance	25		8		25		8
Total gains (losses) included in net income attributable to assets still held	0		0		0		0
Fixed maturity securities | U.S. corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	2,368	[3]	2,644	[4]	2,400	[3]	2,683	[5]
Total realized and unrealized gains (losses), Included in net income	6	[3]	6	[4]	11	[3]	8	[5]
Total realized and unrealized gains (losses), Included in OCI	40	[3]	(49)	[4]	69	[3]	(31)	[5]
Purchases	55	[3]	37	[4]	145	[3]	93	[5]
Sales	(39)	[3]	(24)	[4]	(39)	[3]	(121)	[5]
Issuances	0	[3]	0	[4]	0	[3]	0	[5]
Settlements	(58)	[3]	(185)	[4]	(100)	[3]	(236)	[5]
Transfer into Level 3	87	[3]	50	[4]	101	[3]	112	[5]
Transfer out of Level 3	(36)	[3]	(20)	[4]	(164)	[3]	(49)	[5]
Ending balance	2,423	[3]	2,459	[4],[5]	2,423	[3]	2,459	[4],[5]
Total gains (losses) included in net income attributable to assets still held	7	[3]	5	[4]	12	[3]	4	[5]
Fixed maturity securities | Corporate - non-U.S.
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	1,798		1,970		1,819		1,983	[5]
Total realized and unrealized gains (losses), Included in net income	1		0		2		1	[5]
Total realized and unrealized gains (losses), Included in OCI	39		(37)		48		(28)	[5]
Purchases	132		16		168		69	[5]
Sales	(76)		(19)		(76)		(19)	[5]
Issuances	0		0		0		0	[5]
Settlements	(55)		(84)		(90)		(107)	[5]
Transfer into Level 3	15		0		15		0	[5]
Transfer out of Level 3	0		0		(32)		(53)	[5]
Ending balance	1,854		1,846	[5]	1,854		1,846	[5]
Total gains (losses) included in net income attributable to assets still held	1		0		2		1	[5]
Fixed maturity securities | Residential mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	93		130		105		157
Total realized and unrealized gains (losses), Included in net income	0		(1)		0		(2)
Total realized and unrealized gains (losses), Included in OCI	1		0		2		1
Purchases	0		0		0		0
Sales	0		(5)		(23)		(5)
Issuances	0		0		0		0
Settlements	(2)		(8)		(5)		(19)
Transfer into Level 3	11		0		24		0
Transfer out of Level 3	(30)		0		(30)		(16)
Ending balance	73		116		73		116
Total gains (losses) included in net income attributable to assets still held	0		1		0		0
Fixed maturity securities | Commercial mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	13		26		6		35
Total realized and unrealized gains (losses), Included in net income	0		(2)		0		(4)
Total realized and unrealized gains (losses), Included in OCI	1		1		3		(1)
Purchases	0		0		0		0
Sales	0		0		0		0
Issuances	0		0		0		0
Settlements	(1)		(16)		(2)		(26)
Transfer into Level 3	0		4		6		9
Transfer out of Level 3	(8)		0		(8)		0
Ending balance	5		13		5		13
Total gains (losses) included in net income attributable to assets still held	0		(1)		0		(3)
Fixed maturity securities | Other asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	1,153	[3]	951	[4]	1,166	[3]	864	[5]
Total realized and unrealized gains (losses), Included in net income	2	[3]	4	[4]	3	[3]	3	[5]
Total realized and unrealized gains (losses), Included in OCI	11	[3]	4	[4]	7	[3]	15	[5]
Purchases	195	[3]	59	[4]	211	[3]	124	[5]
Sales	0	[3]	0	[4]	(5)	[3]	(44)	[5]
Issuances	0	[3]	0	[4]	0	[3]	0	[5]
Settlements	(41)	[3]	(41)	[4]	(78)	[3]	(71)	[5]
Transfer into Level 3	22	[3]	44	[4]	58	[3]	130	[5]
Transfer out of Level 3	(74)	[3]	0	[4]	(94)	[3]	0	[5]
Ending balance	1,268	[3]	1,021	[4],[5]	1,268	[3]	1,021	[4],[5]
Total gains (losses) included in net income attributable to assets still held	0	[3]	3	[4]	1	[3]	3	[5]
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	78		92		78		99
Total realized and unrealized gains (losses), Included in net income	0		2		0		2
Total realized and unrealized gains (losses), Included in OCI	0		(1)		0		(1)
Purchases	0		1		0		1
Sales	(11)		(6)		(11)		(13)
Issuances	0		0		0		0
Settlements	0		0		0
Transfer into Level 3	0		0		0		0
Transfer out of Level 3	0		0		0		0
Ending balance	67		88		67		88
Total gains (losses) included in net income attributable to assets still held	0		0		0		0
Other invested assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	51		92		59		110
Total realized and unrealized gains (losses), Included in net income	(11)		2		(20)		(7)
Total realized and unrealized gains (losses), Included in OCI	0		0		0		0
Purchases	4		7		10		14
Sales	(1)		(29)		(1)		(40)
Issuances	0		0		0		0
Settlements	(2)		(19)		(7)		(24)
Transfer into Level 3	0		0		0		0
Transfer out of Level 3	0		0		0		0
Ending balance	41		53		41		53
Total gains (losses) included in net income attributable to assets still held	(11)		(1)		(18)		(12)
Other invested assets | Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	20		25		25		34
Total realized and unrealized gains (losses), Included in net income	(11)		(2)		(20)		(14)
Total realized and unrealized gains (losses), Included in OCI	0		0		0		0
Purchases	4		7		10		14
Sales	(1)		0		(1)		0
Issuances	0		0		0		0
Settlements	(2)		(11)		(4)		(15)
Transfer into Level 3	0		0		0		0
Transfer out of Level 3	0		0		0		0
Ending balance	10		19		10		19
Total gains (losses) included in net income attributable to assets still held	(11)		(1)		(18)		(14)
Other invested assets | Trading Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	31		67		34		76
Total realized and unrealized gains (losses), Included in net income	0		4		0		7
Total realized and unrealized gains (losses), Included in OCI	0		0		0		0
Purchases	0		0		0		0
Sales	0		(29)		0		(40)
Issuances	0		0		0		0
Settlements	0		(8)		(3)		(9)
Transfer into Level 3	0		0		0		0
Transfer out of Level 3	0		0		0		0
Ending balance	31		34		31		34
Total gains (losses) included in net income attributable to assets still held	0		0		0		2
Other invested assets | Interest rate swaps | Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance			1				2
Total realized and unrealized gains (losses), Included in net income			(1)				(1)
Total realized and unrealized gains (losses), Included in OCI			0				0
Purchases			0				0
Sales			0				0
Issuances			0				0
Settlements			0				(1)
Transfer into Level 3			0				0
Transfer out of Level 3			0				0
Ending balance			0				0
Total gains (losses) included in net income attributable to assets still held			(1)				(1)
Other invested assets | Credit default swaps | Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	8		7		10		7
Total realized and unrealized gains (losses), Included in net income	0		1		0		4
Total realized and unrealized gains (losses), Included in OCI	0		0		0		0
Purchases	0		0		0		0
Sales	0		0		0		0
Issuances	0		0		0		0
Settlements	(2)		(2)		(4)		(5)
Transfer into Level 3	0		0		0		0
Transfer out of Level 3	0		0		0		0
Ending balance	6		6		6		6
Total gains (losses) included in net income attributable to assets still held	0		1		0		3
Other invested assets | Equity index options | Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	11		17		12		25
Total realized and unrealized gains (losses), Included in net income	(11)		(2)		(18)		(17)
Total realized and unrealized gains (losses), Included in OCI	0		0		0		0
Purchases	4		7		10		14
Sales	0		0		0		0
Issuances	0		0		0		0
Settlements	0		(9)		0		(9)
Transfer into Level 3	0		0		0		0
Transfer out of Level 3	0		0		0		0
Ending balance	4		13		4		13
Total gains (losses) included in net income attributable to assets still held	(11)		(1)		(18)		(16)
Other invested assets | Other foreign currency contracts | Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	1				3
Total realized and unrealized gains (losses), Included in net income	0				(2)
Total realized and unrealized gains (losses), Included in OCI	0				0
Purchases	0				0
Sales	(1)				(1)
Issuances	0				0
Settlements	0				0
Transfer into Level 3	0				0
Transfer out of Level 3	0				0
Ending balance	0				0
Total gains (losses) included in net income attributable to assets still held	$ 0				$ 0

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

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

[3] 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.

[4] The transfers into and out of Level 3 were primarily related to private fixed rate U.S. corporate and structured securities. For private fixed rate U.S. corporate securities, the transfers into and out of Level 3 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. For structured securities, the transfers into and out of Level 3 were attributable to the changes in the observability of inputs used in the valuation as a result of liquidity or marketability of certain instruments that had a significant impact on the primary pricing source used to value the instruments.

[5] The transfers into and out of Level 3 were primarily related to private fixed rate U.S. corporate and corporate-non-U.S. securities and structured securities. For private fixed rate U.S. corporate and corporate-non-U.S. securities, the transfers into and out of Level 3 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. For structured securities, the transfers into and out of Level 3 were attributable to the changes in the observability of inputs used in the valuation as a result of liquidity or marketability of certain instruments that had a significant impact on the primary pricing source used to value the instruments.