Derivative Financial Instruments (Details 2) (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
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	273,784	268,117
Estimated Fair Value Assets	12,000	12,248
Estimated Fair Value Liabilities	4,070	3,493
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	89,511	71,923
Estimated Fair Value Assets	5,998	5,410
Estimated Fair Value Liabilities	2,471	2,107
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate floors [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
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate caps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	49,547	49,665
Estimated Fair Value Assets	78	102
Estimated Fair Value Liabilities	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate futures [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	12,469	14,965
Estimated Fair Value Assets	10	25
Estimated Fair Value Liabilities	20	19
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate options [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	16,065	16,988
Estimated Fair Value Assets	860	896
Estimated Fair Value Liabilities	12	6
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate forwards [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	0	13,068
Estimated Fair Value Assets	0	76
Estimated Fair Value Liabilities	0	91
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Synthetic GICs [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	4,541	4,454
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Foreign currency swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	8,133	6,871
Estimated Fair Value Assets	253	320
Estimated Fair Value Liabilities	716	656
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Foreign currency forwards [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	5,744	6,630
Estimated Fair Value Assets	55	145
Estimated Fair Value Liabilities	44	38
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Currency futures [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	289	633
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Currency options [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	201	1,321
Estimated Fair Value Assets	0	6
Estimated Fair Value Liabilities	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Credit default swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	13,326	13,136
Estimated Fair Value Assets	100	326
Estimated Fair Value Liabilities	41	113
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Equity futures [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	7,367	7,053
Estimated Fair Value Assets	65	26
Estimated Fair Value Liabilities	2	10
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Equity Options [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
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Variance swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	20,056	18,801
Estimated Fair Value Assets	171	397
Estimated Fair Value Liabilities	239	75
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Total rate of return swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	2,073	1,644
Estimated Fair Value Assets	10	10
Estimated Fair Value Liabilities	$ 90	$ 34