Derivatives (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Derivatives Designated as Hedging Instruments [Member]	Dec. 31, 2011 Derivatives Designated as Hedging Instruments [Member]	Dec. 31, 2012 Derivatives Designated as Hedging Instruments [Member] Fair Value Hedges [Member]	Dec. 31, 2011 Derivatives Designated as Hedging Instruments [Member] Fair Value Hedges [Member]	Dec. 31, 2012 Derivatives Designated as Hedging Instruments [Member] Fair Value Hedges [Member] Interest rate swaps [Member]	Dec. 31, 2011 Derivatives Designated as Hedging Instruments [Member] Fair Value Hedges [Member] Interest rate swaps [Member]	Dec. 31, 2012 Derivatives Designated as Hedging Instruments [Member] Fair Value Hedges [Member] Foreign currency swaps [Member]	Dec. 31, 2011 Derivatives Designated as Hedging Instruments [Member] Fair Value Hedges [Member] Foreign currency swaps [Member]	Dec. 31, 2012 Derivatives Designated as Hedging Instruments [Member] Fair Value Hedges [Member] Foreign currency forwards [Member]	Dec. 31, 2011 Derivatives Designated as Hedging Instruments [Member] Fair Value Hedges [Member] Foreign currency forwards [Member]	Dec. 31, 2012 Derivatives Designated as Hedging Instruments [Member] Cash Flow Hedges [Member]	Dec. 31, 2011 Derivatives Designated as Hedging Instruments [Member] Cash Flow Hedges [Member]	Dec. 31, 2012 Derivatives Designated as Hedging Instruments [Member] Cash Flow Hedges [Member] Interest rate swaps [Member]	Dec. 31, 2011 Derivatives Designated as Hedging Instruments [Member] Cash Flow Hedges [Member] Interest rate swaps [Member]	Dec. 31, 2012 Derivatives Designated as Hedging Instruments [Member] Cash Flow Hedges [Member] Interest rate forwards [Member]	Dec. 31, 2011 Derivatives Designated as Hedging Instruments [Member] Cash Flow Hedges [Member] Interest rate forwards [Member]	Dec. 31, 2012 Derivatives Designated as Hedging Instruments [Member] Cash Flow Hedges [Member] Foreign currency swaps [Member]	Dec. 31, 2011 Derivatives Designated as Hedging Instruments [Member] Cash Flow Hedges [Member] Foreign currency swaps [Member]	Dec. 31, 2012 Derivatives Designated as Hedging Instruments [Member] Cash Flow Hedges [Member] Credit forwards [Member]	Dec. 31, 2011 Derivatives Designated as Hedging Instruments [Member] Cash Flow Hedges [Member] Credit forwards [Member]	Dec. 31, 2012 Derivatives Designated as Hedging Instruments [Member] Foreign Operations Hedges [Member]	Dec. 31, 2011 Derivatives Designated as Hedging Instruments [Member] Foreign Operations Hedges [Member]	Dec. 31, 2012 Derivatives Designated as Hedging Instruments [Member] Foreign Operations Hedges [Member] Foreign currency forwards [Member]	Dec. 31, 2011 Derivatives Designated as Hedging Instruments [Member] Foreign Operations Hedges [Member] Foreign currency forwards [Member]	Dec. 31, 2012 Derivatives Designated as Hedging Instruments [Member] Foreign Operations Hedges [Member] Currency options [Member]	Mar. 31, 2011 Derivatives Designated as Hedging Instruments [Member] Foreign Operations Hedges [Member] Currency options [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Interest rate swaps [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Interest rate swaps [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Interest rate forwards [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Interest rate forwards [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Interest rate floors [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Interest rate floors [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Interest rate caps [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Interest rate caps [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Interest rate futures [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Interest rate futures [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Interest rate options [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Interest rate options [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Synthetic GICs [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Synthetic GICs [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Foreign currency swaps [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Foreign currency swaps [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Foreign currency forwards [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Foreign currency forwards [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Currency futures [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Currency futures [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Currency options [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Currency options [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Credit default swaps [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Credit default swaps [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Equity futures [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Equity futures [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Equity Options [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Equity Options [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Variance swaps [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Variance swaps [Member]	Dec. 31, 2012 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Total rate of return swaps [Member]	Dec. 31, 2011 Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] Total rate of return swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	$ 334,351	$ 290,021	$ 28,866	$ 21,904	$ 8,584	$ 9,630	$ 5,397	$ 4,580	$ 3,187	$ 3,220	$ 0	$ 1,830	$ 13,355	$ 10,585	$ 3,642	$ 3,230	$ 675	$ 965	$ 9,038	$ 6,370	$ 0	$ 20	$ 6,927	$ 1,689	$ 2,552	$ 1,689	$ 4,375	$ 0	$ 305,485	$ 268,117	$ 83,250	$ 71,923	$ 0	$ 13,068	$ 56,246	$ 23,866	$ 49,465	$ 49,665	$ 11,684	$ 14,965	$ 16,328	$ 16,988	$ 4,162	$ 4,454	$ 8,208	$ 6,871	$ 9,202	$ 6,630	$ 1,408	$ 633	$ 129	$ 1,321	$ 12,553	$ 13,136	$ 7,008	$ 7,053	$ 22,920	$ 17,099	$ 19,830	$ 18,801	$ 3,092	$ 1,644
Estimated Fair Value Assets	13,777	16,200	3,402	3,952	2,253	2,386	1,921	1,884	332	500	0	2	1,063	1,513	705	947	139	210	219	352	0	4	86	53	43	53	43	0	10,375	12,248	5,201	5,410	0	76	1,174	1,246	74	102	1	25	640	896	0	0	199	320	26	145	4	0	1	6	90	326	14	26	2,825	3,263	122	397	4	10
Estimated Fair Value Liabilities	$ 5,536	$ 4,011	$ 594	$ 518	$ 175	$ 200	$ 90	$ 92	$ 85	$ 98	$ 0	$ 10	$ 355	$ 306	$ 0	$ 0	$ 0	$ 0	$ 355	$ 306	$ 0	$ 0	$ 64	$ 12	$ 61	$ 12	$ 3	$ 0	$ 4,942	$ 3,493	$ 2,043	$ 2,107	$ 0	$ 91	$ 837	$ 165	$ 0	$ 0	$ 38	$ 19	$ 60	$ 6	$ 0	$ 0	$ 736	$ 656	$ 288	$ 38	$ 0	$ 0	$ 0	$ 0	$ 39	$ 113	$ 132	$ 10	$ 356	$ 179	$ 310	$ 75	$ 103	$ 34