Derivatives (Primary Risks) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Notional Amount	$ 386,453	$ 404,895
Estimated Fair Value Assets	9,130	8,595
Estimated Fair Value Liabilities	5,745	6,521
Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	39,592	38,634
Estimated Fair Value Assets	2,623	2,425
Estimated Fair Value Liabilities	800	1,145
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	11,465	12,067
Estimated Fair Value Assets	1,780	1,534
Estimated Fair Value Liabilities	116	290
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedges [Member] | Interest rate swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	6,300	6,419
Estimated Fair Value Assets	1,488	1,282
Estimated Fair Value Liabilities	35	78
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedges [Member] | Foreign currency swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	2,140	2,713
Estimated Fair Value Assets	245	252
Estimated Fair Value Liabilities	80	135
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedges [Member] | Foreign currency forwards [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	3,025	2,935
Estimated Fair Value Assets	47	0
Estimated Fair Value Liabilities	1	77
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	16,583	16,023
Estimated Fair Value Assets	656	491
Estimated Fair Value Liabilities	664	808
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedges [Member] | Interest rate swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	3,011	3,121
Estimated Fair Value Assets	196	83
Estimated Fair Value Liabilities	48	141
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedges [Member] | Interest rate forwards [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	735	450
Estimated Fair Value Assets	38	7
Estimated Fair Value Liabilities	0	7
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedges [Member] | Foreign currency swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	12,837	12,452
Estimated Fair Value Assets	422	401
Estimated Fair Value Liabilities	616	660
Derivatives Designated as Hedging Instruments [Member] | Foreign Operations Hedges [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	11,544	10,544
Estimated Fair Value Assets	187	400
Estimated Fair Value Liabilities	20	47
Derivatives Designated as Hedging Instruments [Member] | Foreign Operations Hedges [Member] | Foreign currency forwards [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	3,178	3,182
Estimated Fair Value Assets	19	82
Estimated Fair Value Liabilities	16	47
Derivatives Designated as Hedging Instruments [Member] | Foreign Operations Hedges [Member] | Currency options [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	8,366	7,362
Estimated Fair Value Assets	168	318
Estimated Fair Value Liabilities	4	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	346,861	366,261
Estimated Fair Value Assets	6,507	6,170
Estimated Fair Value Liabilities	4,945	5,376
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	102,687	107,354
Estimated Fair Value Assets	3,515	3,330
Estimated Fair Value Liabilities	1,617	1,767
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate floors [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	66,943	63,064
Estimated Fair Value Assets	454	451
Estimated Fair Value Liabilities	314	346
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate caps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	34,460	39,460
Estimated Fair Value Assets	126	177
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	5,778	6,011
Estimated Fair Value Assets	2	9
Estimated Fair Value Liabilities	5	9
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate options [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	28,036	40,978
Estimated Fair Value Assets	357	255
Estimated Fair Value Liabilities	220	243
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Synthetic GICs [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	4,405	4,409
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	8,896	9,307
Estimated Fair Value Assets	128	133
Estimated Fair Value Liabilities	645	684
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Foreign currency forwards [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	12,228	11,311
Estimated Fair Value Assets	94	69
Estimated Fair Value Liabilities	122	359
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Currency futures [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	1,340	1,316
Estimated Fair Value Assets	1	1
Estimated Fair Value Liabilities	1	1
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Currency options [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	5,996	2,265
Estimated Fair Value Assets	103	53
Estimated Fair Value Liabilities	21	48
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Credit default swaps - purchased [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	3,627	3,725
Estimated Fair Value Assets	7	7
Estimated Fair Value Liabilities	43	51
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Credit default swaps - written [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	9,848	9,055
Estimated Fair Value Assets	146	166
Estimated Fair Value Liabilities	7	1
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Equity futures [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	5,598	5,157
Estimated Fair Value Assets	3	1
Estimated Fair Value Liabilities	72	43
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Equity Options [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	31,467	37,411
Estimated Fair Value Assets	1,370	1,344
Estimated Fair Value Liabilities	1,151	1,068
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Variance swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	21,919	21,636
Estimated Fair Value Assets	199	174
Estimated Fair Value Liabilities	646	577
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Total rate of return swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	3,633	3,802
Estimated Fair Value Assets	2	0
Estimated Fair Value Liabilities	$ 81	$ 179