Derivative Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Notional Amount	$ 289,962	$ 290,021
Estimated Fair Value Assets	12,447	16,200
Estimated Fair Value Liabilities	4,207	4,011
Interest rate swaps [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	90,460	79,733
Estimated Fair Value Assets	6,595	8,241
Estimated Fair Value Liabilities	1,994	2,199
Interest rate floors [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	23,866	23,866
Estimated Fair Value Assets	1,043	1,246
Estimated Fair Value Liabilities	143	165
Interest rate caps [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	43,665	49,665
Estimated Fair Value Assets	92	102
Estimated Fair Value Liabilities	0	0
Interest rate futures [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	14,781	14,965
Estimated Fair Value Assets	20	25
Estimated Fair Value Liabilities	43	19
Interest rate options [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	16,051	16,988
Estimated Fair Value Assets	516	896
Estimated Fair Value Liabilities	79	6
Interest rate forwards [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	3,189	14,033
Estimated Fair Value Assets	119	286
Estimated Fair Value Liabilities	5	91
Synthetic GICs [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	4,484	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	16,995	16,461
Estimated Fair Value Assets	1,032	1,172
Estimated Fair Value Liabilities	1,064	1,060
Foreign currency forwards [Member] | Foreign currency [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	10,301	10,149
Estimated Fair Value Assets	64	200
Estimated Fair Value Liabilities	295	60
Currency futures [Member] | Foreign currency [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	827	633
Estimated Fair Value Assets	1	0
Estimated Fair Value Liabilities	0	0
Currency options [Member] | Foreign currency [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	1,446	1,321
Estimated Fair Value Assets	22	6
Estimated Fair Value Liabilities	2	0
Credit default swaps [Member] | Credit [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	12,599	13,136
Estimated Fair Value Assets	173	326
Estimated Fair Value Liabilities	51	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	6,498	7,053
Estimated Fair Value Assets	26	26
Estimated Fair Value Liabilities	8	10
Equity Options [Member] | Equity market [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	23,575	17,099
Estimated Fair Value Assets	2,563	3,263
Estimated Fair Value Liabilities	251	179
Variance swaps [Member] | Equity market [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	19,108	18,801
Estimated Fair Value Assets	178	397
Estimated Fair Value Liabilities	181	75
Total rate of return swaps [Member] | Equity market [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	2,117	1,644
Estimated Fair Value Assets	3	10
Estimated Fair Value Liabilities	$ 91	$ 34