Derivative Financial Instruments (Details) (USD $) In Millions, except Share data, unless otherwise specified	Jun. 30, 2012 contract	Dec. 31, 2011 contract
Derivative Financial Instruments
Securities pledged in the form of margin deposits	$ 4
Derivatives, Fair Value
Total asset derivatives, Notional amount	8,296	11,079
Total liability derivatives, Notional amount	7,834	7,085
Total derivatives, Notional amount	16,130	18,164
Total asset derivatives, Number of contracts	14,041	16,231
Total liability derivatives, Number of contracts	15,175	14,985
Total derivatives, Number of contracts	29,216	31,216
Asset derivatives, Gross asset	244	266
Asset derivatives, Gross liability	(86)	(158)
Total asset derivatives, Fair value, net	158	108
Liability derivatives, Gross asset	23	15
Liability derivatives, Gross liability	(857)	(863)
Total liability derivatives, Fair value, net	(834)	(848)
Total derivatives, Fair value, net	(676)	(740)
Number of stock warrants held by the company related to derivative contracts	837,100	837,100
Derivatives designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	112	271
Total liability derivatives, Notional amount	66	78
Asset derivatives, Gross asset		3
Asset derivatives, Gross liability	(6)	(16)
Total asset derivatives, Fair value, net	(6)	(13)
Liability derivatives, Gross asset	2
Liability derivatives, Gross liability	(7)	(12)
Total liability derivatives, Fair value, net	(5)	(12)
Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	8,184	10,808
Total liability derivatives, Notional amount	7,768	7,007
Total asset derivatives, Number of contracts	14,041	16,231
Total liability derivatives, Number of contracts	15,175	14,985
Asset derivatives, Gross asset	244	263
Asset derivatives, Gross liability	(80)	(142)
Total asset derivatives, Fair value, net	164	121
Liability derivatives, Gross asset	21	15
Liability derivatives, Gross liability	(850)	(851)
Total liability derivatives, Fair value, net	(829)	(836)
Interest rate swap agreements | Derivatives designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	27	144
Asset derivatives, Gross liability		(8)
Total asset derivatives, Fair value, net		(8)
Interest rate swap agreements | Derivatives designated as accounting hedging instruments | Other liabilities and accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount		28
Liability derivatives, Gross liability		(5)
Total liability derivatives, Fair value, net		(5)
Interest rate swap agreements | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	6,941	8,028
Asset derivatives, Gross asset	57	137
Asset derivatives, Gross liability	(12)	(15)
Total asset derivatives, Fair value, net	45	122
Interest rate swap agreements | Derivatives not designated as accounting hedging instruments | Other liabilities and accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	1,085	85
Liability derivatives, Gross asset	16	8
Total liability derivatives, Fair value, net	16	8
Foreign currency swap agreements | Derivatives designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	85	127
Asset derivatives, Gross asset		3
Asset derivatives, Gross liability	(6)	(8)
Total asset derivatives, Fair value, net	(6)	(5)
Foreign currency swap agreements | Derivatives designated as accounting hedging instruments | Other liabilities and accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	66	50
Liability derivatives, Gross asset	2
Liability derivatives, Gross liability	(7)	(7)
Total liability derivatives, Fair value, net	(5)	(7)
Foreign currency swap agreements | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount		50
Asset derivatives, Gross asset		6
Total asset derivatives, Fair value, net		6
Interest rate swaption agreements | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	250	500
Interest rate cap and floor agreements | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	449	1,591
Asset derivatives, Gross asset	1
Asset derivatives, Gross liability	(12)	(12)
Total asset derivatives, Fair value, net	(11)	(12)
Interest rate cap and floor agreements | Derivatives not designated as accounting hedging instruments | Other liabilities and accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	841	914
Liability derivatives, Gross liability	(7)	(9)
Total liability derivatives, Fair value, net	(7)	(9)
Financial futures contracts and options | Derivatives not designated as accounting hedging instruments | Other assets
Derivatives, Fair Value
Total asset derivatives, Number of contracts	2	40
Financial futures contracts and options | Derivatives not designated as accounting hedging instruments | Other liabilities and accrued expenses
Derivatives, Fair Value
Total liability derivatives, Number of contracts	630
Options, futures and warrants | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	150	163
Total asset derivatives, Number of contracts	13,740	15,180
Asset derivatives, Gross asset	171	104
Total asset derivatives, Fair value, net	171	104
Options, futures and warrants | Derivatives not designated as accounting hedging instruments | Other assets
Derivatives, Fair Value
Total asset derivatives, Number of contracts	299	1,011
Asset derivatives, Gross asset	3
Total asset derivatives, Fair value, net	3
Options, futures and warrants | Derivatives not designated as accounting hedging instruments | Other liabilities and accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	2
Total liability derivatives, Number of contracts	14,545	14,985
Liability derivatives, Gross liability	(79)	(49)
Total liability derivatives, Fair value, net	(79)	(49)
Foreign currency forwards and options | Derivatives not designated as accounting hedging instruments | Other liabilities and accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	42
Liability derivatives, Gross liability	(1)
Total liability derivatives, Fair value, net	(1)
Conversion options | Derivatives not designated as accounting hedging instruments | Fixed income securities
Derivatives, Fair Value
Total asset derivatives, Notional amount	5	5
Equity-indexed call options | Derivatives not designated as accounting hedging instruments | Fixed income securities
Derivatives, Fair Value
Total asset derivatives, Notional amount	125	150
Asset derivatives, Gross asset	10	11
Total asset derivatives, Fair value, net	10	11
Credit default swaps | Derivatives not designated as accounting hedging instruments | Fixed income securities
Derivatives, Fair Value
Total asset derivatives, Notional amount	127	170
Asset derivatives, Gross liability	(55)	(113)
Total asset derivatives, Fair value, net	(55)	(113)
Guaranteed accumulation benefits | Derivatives not designated as accounting hedging instruments | Contractholder funds
Derivatives, Fair Value
Total liability derivatives, Notional amount	853	917
Liability derivatives, Gross liability	(96)	(105)
Total liability derivatives, Fair value, net	(96)	(105)
Guaranteed withdrawal benefits | Derivatives not designated as accounting hedging instruments | Contractholder funds
Derivatives, Fair Value
Total liability derivatives, Notional amount	571	613
Liability derivatives, Gross liability	(52)	(57)
Total liability derivatives, Fair value, net	(52)	(57)
Embedded derivative financial instruments | Derivatives not designated as accounting hedging instruments | Contractholder funds
Derivatives, Fair Value
Total liability derivatives, Notional amount	3,756	3,996
Liability derivatives, Gross liability	(551)	(553)
Total liability derivatives, Fair value, net	(551)	(553)
Other embedded derivative financial instruments | Derivatives not designated as accounting hedging instruments | Contractholder funds
Derivatives, Fair Value
Total liability derivatives, Notional amount	85	85
Liability derivatives, Gross liability	(8)	(8)
Total liability derivatives, Fair value, net	(8)	(8)
Credit default swaps - buying protection | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	73	110
Asset derivatives, Gross asset	1	4
Asset derivatives, Gross liability	(1)	(2)
Total asset derivatives, Fair value, net		2
Credit default swaps - buying protection | Derivatives not designated as accounting hedging instruments | Other liabilities and accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	228	127
Liability derivatives, Gross asset	5	6
Liability derivatives, Gross liability	(1)	(1)
Total liability derivatives, Fair value, net	4	5
Credit default swaps - selling protection | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	60	32
Credit default swaps - selling protection | Derivatives not designated as accounting hedging instruments | Other liabilities and accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	305	270
Liability derivatives, Gross asset		1
Liability derivatives, Gross liability	(55)	(69)
Total liability derivatives, Fair value, net	(55)	(68)
Other contracts | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount		5
Other contracts | Derivatives not designated as accounting hedging instruments | Other assets
Derivatives, Fair Value
Total asset derivatives, Notional amount	4	4
Asset derivatives, Gross asset	1	1
Total asset derivatives, Fair value, net	$ 1	$ 1