Derivative Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Notional Amount	$ 303,246	$ 290,021
Estimated Fair Value Assets	15,728	16,200
Estimated Fair Value Liabilities	4,711	4,011
Interest rate swaps [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	98,609	79,733
Estimated Fair Value Assets	8,930	8,241
Estimated Fair Value Liabilities	2,571	2,199
Interest rate floors [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	23,366	23,866
Estimated Fair Value Assets	1,304	1,246
Estimated Fair Value Liabilities	174	165
Interest rate caps [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	49,547	49,665
Estimated Fair Value Assets	78	102
Estimated Fair Value Liabilities	0	0
Interest rate futures [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	12,469	14,965
Estimated Fair Value Assets	10	25
Estimated Fair Value Liabilities	20	19
Interest rate options [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	16,065	16,988
Estimated Fair Value Assets	860	896
Estimated Fair Value Liabilities	12	6
Interest rate forwards [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	770	14,033
Estimated Fair Value Assets	178	286
Estimated Fair Value Liabilities	0	91
Synthetic GICs [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	4,541	4,454
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	0	0
Foreign currency swaps [Member] | Foreign currency [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	20,223	16,461
Estimated Fair Value Assets	846	1,172
Estimated Fair Value Liabilities	1,158	1,060
Foreign currency forwards [Member] | Foreign currency [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	10,598	10,149
Estimated Fair Value Assets	79	200
Estimated Fair Value Liabilities	97	60
Currency futures [Member] | Foreign currency [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	289	633
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	0	0
Currency options [Member] | Foreign currency [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	2,851	1,321
Estimated Fair Value Assets	1	6
Estimated Fair Value Liabilities	46	0
Credit default swaps [Member] | Credit [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	13,326	13,136
Estimated Fair Value Assets	100	326
Estimated Fair Value Liabilities	41	113
Credit forwards [Member] | Credit [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	0	20
Estimated Fair Value Assets	0	4
Estimated Fair Value Liabilities	0	0
Equity futures [Member] | Equity market [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	7,367	7,053
Estimated Fair Value Assets	65	26
Estimated Fair Value Liabilities	2	10
Equity Options [Member] | Equity market [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	21,096	17,099
Estimated Fair Value Assets	3,096	3,263
Estimated Fair Value Liabilities	261	179
Variance swaps [Member] | Equity market [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	20,056	18,801
Estimated Fair Value Assets	171	397
Estimated Fair Value Liabilities	239	75
Total rate of return swaps [Member] | Equity market [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	2,073	1,644
Estimated Fair Value Assets	10	10
Estimated Fair Value Liabilities	$ 90	$ 34