Changes in Available-For-Sale Investments and Derivatives Classified as Level 3 (Detail) (USD $) In Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	$ 574		$ 364		$ 560		$ 5,057
Effect of change in accounting principle							(575)	[1]
Revised balance, beginning of period							4,482
Realized gains or losses included in earnings	(215)		30		(298)		98
Unrealized gains or losses included in other comprehensive income	19		82		(6)		171
Purchases	0		0		0		0
Issuances	0		0		0		0
Sales	(3)		0		(3)		(763)
Settlements	132		(2)		254		(2)
Transfers into Level 3	(31)	[2]	72	[3]	(31)	[2]	770	[3]
Transfers out of Level 3	(380)	[4]	(123)	[5]	(380)	[6]	(4,333)	[5]
Balance, end of period	96		423		96		423
Change in unrealized gains (losses) still held	(170)	[7]	30	[8]	(229)	[7]	(15)	[8]
Mortgage- and asset-backed Securities | Fixed Maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	257		282		267		62
Effect of change in accounting principle							0	[1]
Revised balance, beginning of period							62
Realized gains or losses included in earnings	(1)		(1)		(7)		(1)
Unrealized gains or losses included in other comprehensive income	18		17		20		19
Purchases	0		0		0		0
Issuances	0		0		0		0
Sales	0		0		0		(1)
Settlements	(2)		(2)		(8)		(2)
Transfers into Level 3	0	[2]	18	[3]	0	[2]	237	[3]
Transfers out of Level 3	(4)	[4]	(44)	[5]	(4)	[6]	(44)	[5]
Balance, end of period	268		270		268		270
Change in unrealized gains (losses) still held	(1)	[7]	0	[8]	(7)	[7]	0	[8]
Public Utilities | Fixed Maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	0		27		0		497
Effect of change in accounting principle							0	[1]
Revised balance, beginning of period							497
Realized gains or losses included in earnings	0		0		0		0
Unrealized gains or losses included in other comprehensive income	0		0		0		(9)
Purchases	0		0		0		0
Issuances	0		0		0		0
Sales	0		0		0		(2)
Settlements	0		0		0		0
Transfers into Level 3	0	[2]	0	[3]	0	[2]	0	[3]
Transfers out of Level 3	0	[4]	(27)	[5]	0	[6]	(486)	[5]
Balance, end of period	0		0		0		0
Change in unrealized gains (losses) still held	0	[7]	0	[8]	0	[7]	0	[8]
Sovereign and Supranational | Fixed Maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	0		0		0		293
Effect of change in accounting principle							0	[1]
Revised balance, beginning of period							293
Realized gains or losses included in earnings	0		0		0		0
Unrealized gains or losses included in other comprehensive income	0		0		0		5
Purchases	0		0		0		0
Issuances	0		0		0		0
Sales	0		0		0		0
Settlements	0		0		0		0
Transfers into Level 3	0	[2]	0	[3]	0	[2]	0	[3]
Transfers out of Level 3	0	[4]	0	[5]	0	[6]	(298)	[5]
Balance, end of period	0		0		0		0
Change in unrealized gains (losses) still held	0	[7]	0	[8]	0	[7]	0	[8]
Banks/financial Institutions | Fixed Maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	398		352		386		1,240
Effect of change in accounting principle							0	[1]
Revised balance, beginning of period							1,240
Realized gains or losses included in earnings	0		0		1		5
Unrealized gains or losses included in other comprehensive income	3		65		14		99
Purchases	0		0		0		0
Issuances	0		0		0		0
Sales	0		0		0		(175)
Settlements	0		0		0		0
Transfers into Level 3	0	[2]	0	[3]	0	[2]	330	[3]
Transfers out of Level 3	(376)	[4]	0	[5]	(376)	[6]	(1,082)	[5]
Balance, end of period	25		417		25		417
Change in unrealized gains (losses) still held	0	[7]	0	[8]	1	[7]	0	[8]
Other Corporate | Fixed Maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	0		52		0		1,248
Effect of change in accounting principle							0	[1]
Revised balance, beginning of period							1,248
Realized gains or losses included in earnings	0		0		0		0
Unrealized gains or losses included in other comprehensive income	0		0		0		6
Purchases	0		0		0		0
Issuances	0		0		0		0
Sales	0		0		0		0
Settlements	0		0		0		0
Transfers into Level 3	0	[2]	0	[3]	0	[2]	0	[3]
Transfers out of Level 3	0	[4]	(52)	[5]	0	[6]	(1,254)	[5]
Balance, end of period	0		0		0		0
Change in unrealized gains (losses) still held	0	[7]	0	[8]	0	[7]	0	[8]
Collateralized Debt Obligations | Fixed Maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	4		4		5		267
Effect of change in accounting principle							(263)	[1]
Revised balance, beginning of period							4
Realized gains or losses included in earnings	(1)		1		(2)		1
Unrealized gains or losses included in other comprehensive income	0		0		0		0
Purchases	0		0		0		0
Issuances	0		0		0		0
Sales	(3)		0		(3)		0
Settlements	0		0		0		0
Transfers into Level 3	0	[2]	0	[3]	0	[2]	0	[3]
Transfers out of Level 3	0	[4]	0	[5]	0	[6]	0	[5]
Balance, end of period	0		5		0		5
Change in unrealized gains (losses) still held	0	[7]	0	[8]	0	[7]	0	[8]
Banks/financial Institutions | Perpetual Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	0		0		0		1,441
Effect of change in accounting principle							0	[1]
Revised balance, beginning of period							1,441
Realized gains or losses included in earnings	0		0		0		108
Unrealized gains or losses included in other comprehensive income	0		0		0		51
Purchases	0		0		0		0
Issuances	0		0		0		0
Sales	0		0		0		(585)
Settlements	0		0		0		0
Transfers into Level 3	0	[2]	0	[3]	0	[2]	149	[3]
Transfers out of Level 3	0	[4]	0	[5]	0	[6]	(1,164)	[5]
Balance, end of period	0		0		0		0
Change in unrealized gains (losses) still held	0	[7]	0	[8]	0	[7]	0	[8]
Equity Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	4		4		4		9
Effect of change in accounting principle							0	[1]
Revised balance, beginning of period							9
Realized gains or losses included in earnings	0		0		0		0
Unrealized gains or losses included in other comprehensive income	0		0		0		0
Purchases	0		0		0		0
Issuances	0		0		0		0
Sales	0		0		0		0
Settlements	0		0		0		0
Transfers into Level 3	0	[2]	0	[3]	0	[2]	0	[3]
Transfers out of Level 3	0	[4]	0	[5]	0	[6]	(5)	[5]
Balance, end of period	4		4		4		4
Change in unrealized gains (losses) still held	0	[7]	0	[8]	0	[7]	0	[8]
Interest rate swaps | Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	0				0
Realized gains or losses included in earnings	0				0
Unrealized gains or losses included in other comprehensive income	0				0
Purchases	0				0
Issuances	0				0
Sales	0				0
Settlements	0				0
Transfers into Level 3	59	[2]			59	[2]
Transfers out of Level 3	0	[4]			0	[6]
Balance, end of period	59				59
Change in unrealized gains (losses) still held	0	[7]			0	[7]
Foreign currency swaps | Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	164		0		241		0
Effect of change in accounting principle							0	[1]
Revised balance, beginning of period							0
Realized gains or losses included in earnings	(138)		0		(177)		0
Unrealized gains or losses included in other comprehensive income	(2)		0		(40)		0
Purchases	0		0		0		0
Issuances	0		0		0		0
Sales	0		0		0		0
Settlements	0		0		0		0
Transfers into Level 3	(90)	[2]	54	[3]	(90)	[2]	54	[3]
Transfers out of Level 3	0	[4]	0	[5]	0	[6]	0	[5]
Balance, end of period	(66)		54		(66)		54
Change in unrealized gains (losses) still held	(138)	[7]	0	[8]	(177)	[7]	0	[8]
Credit default swaps | Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	(253)		(357)		(343)		0
Effect of change in accounting principle							(312)	[1]
Revised balance, beginning of period							(312)
Realized gains or losses included in earnings	(75)		30		(113)		(15)
Unrealized gains or losses included in other comprehensive income	0		0		0		0
Purchases	0		0		0		0
Issuances	0		0		0		0
Sales	0		0		0		0
Settlements	134		0		262		0
Transfers into Level 3	0	[2]	0	[3]	0	[2]	0	[3]
Transfers out of Level 3	0	[4]	0	[5]	0	[6]	0	[5]
Balance, end of period	(194)		(327)		(194)		(327)
Change in unrealized gains (losses) still held	$ (31)	[7]	$ 30	[8]	$ (46)	[7]	$ (15)	[8]

[1] Change in accounting for VIEs effective January 1, 2010. See Notes 1, 3, and 4 for additional information.

[2] Due to a lack of visibility to observe significant inputs to price

[3] Due to a lack of visibility to observe significant inputs to price and credit events of respective issuers of securities to below investment grade

[4] A result of changing our pricing methodology to using a third party pricing vendor for estimating fair value instead of obtaining pricing of the securities from brokers or arrangers

[5] A result of changing our pricing methodology to using a pricing index for estimating fair value instead of obtaining pricing of the securities from brokers or arrangers

[6] A result of changing our pricing methodology to using a third party pricing vendor for estimating fair value instead of obtaining pricing of the securities from brokers or arrangers.

[7] Represents the amount of total gains or losses for the period, included in earnings, attributable to the change in unrealized gains (losses) relating to assets classified as Level 3 that were still held at September 30, 2011

[8] Represents the amount of total gains or losses for the period, included in earnings, attributable to the change in unrealized gains (losses) relating to assets classified as Level 3 that were still held at September 30, 2010