Derivative Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Notional Amount	$ 295,022	$ 290,021
Estimated Fair Value Assets	16,602	16,200
Estimated Fair Value Liabilities	4,353	4,011
Interest rate swaps [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	95,755	79,733
Estimated Fair Value Assets	9,189	8,241
Estimated Fair Value Liabilities	2,314	2,199
Interest rate floors [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	23,866	23,866
Estimated Fair Value Assets	1,291	1,246
Estimated Fair Value Liabilities	172	165
Interest rate caps [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	46,045	49,665
Estimated Fair Value Assets	54	102
Estimated Fair Value Liabilities	0	0
Interest rate futures [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	14,350	14,965
Estimated Fair Value Assets	16	25
Estimated Fair Value Liabilities	51	19
Interest rate options [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	16,002	16,988
Estimated Fair Value Assets	927	896
Estimated Fair Value Liabilities	5	6
Interest rate forwards [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	1,377	14,033
Estimated Fair Value Assets	197	286
Estimated Fair Value Liabilities	12	91
Synthetic GICs [Member] | Interest rate [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	4,506	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	16,841	16,461
Estimated Fair Value Assets	984	1,172
Estimated Fair Value Liabilities	1,012	1,060
Foreign currency forwards [Member] | Foreign currency [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	9,237	10,149
Estimated Fair Value Assets	205	200
Estimated Fair Value Liabilities	51	60
Currency futures [Member] | Foreign currency [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	934	633
Estimated Fair Value Assets	2	0
Estimated Fair Value Liabilities	1	0
Currency options [Member] | Foreign currency [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	2,551	1,321
Estimated Fair Value Assets	3	6
Estimated Fair Value Liabilities	22	0
Credit default swaps [Member] | Credit [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	13,803	13,136
Estimated Fair Value Assets	168	326
Estimated Fair Value Liabilities	80	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	7,682	7,053
Estimated Fair Value Assets	1	26
Estimated Fair Value Liabilities	236	10
Equity Options [Member] | Equity market [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	20,315	17,099
Estimated Fair Value Assets	3,315	3,263
Estimated Fair Value Liabilities	209	179
Variance swaps [Member] | Equity market [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	19,833	18,801
Estimated Fair Value Assets	216	397
Estimated Fair Value Liabilities	144	75
Total rate of return swaps [Member] | Equity market [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	2,007	1,644
Estimated Fair Value Assets	34	10
Estimated Fair Value Liabilities	$ 44	$ 34