Derivatives (Primary Risks) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Gross Notional Amount	$ 393,049	$ 415,598
Estimated Fair Value Assets	15,791	13,452
Estimated Fair Value Liabilities	7,822	7,022
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Gross Notional Amount	46,972	42,713
Estimated Fair Value Assets	4,734	3,993
Estimated Fair Value Liabilities	2,154	1,353
Derivatives Designated as Hedging Instruments | Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Gross Notional Amount	11,409	11,087
Estimated Fair Value Assets	2,373	2,129
Estimated Fair Value Liabilities	627	412
Derivatives Designated as Hedging Instruments | Fair Value Hedges [Member] | Interest rate swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	5,975	6,044
Estimated Fair Value Assets	2,296	2,064
Estimated Fair Value Liabilities	22	21
Derivatives Designated as Hedging Instruments | Fair Value Hedges [Member] | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	2,699	2,708
Estimated Fair Value Assets	77	65
Estimated Fair Value Liabilities	354	100
Derivatives Designated as Hedging Instruments | Fair Value Hedges [Member] | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Gross Notional Amount	2,735	2,335
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	251	291
Derivatives Designated as Hedging Instruments | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Gross Notional Amount	23,024	21,110
Estimated Fair Value Assets	1,875	1,154
Estimated Fair Value Liabilities	1,508	930
Derivatives Designated as Hedging Instruments | Cash Flow Hedges [Member] | Interest rate swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	2,927	2,560
Estimated Fair Value Assets	666	528
Estimated Fair Value Liabilities	0	0
Derivatives Designated as Hedging Instruments | Cash Flow Hedges [Member] | Interest rate forwards
Derivatives, Fair Value [Line Items]
Gross Notional Amount	200	225
Estimated Fair Value Assets	70	63
Estimated Fair Value Liabilities	0	0
Derivatives Designated as Hedging Instruments | Cash Flow Hedges [Member] | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	19,897	18,325
Estimated Fair Value Assets	1,139	563
Estimated Fair Value Liabilities	1,508	930
Derivatives Designated as Hedging Instruments | Foreign Operations Hedges [Member]
Derivatives, Fair Value [Line Items]
Gross Notional Amount	12,539	10,516
Estimated Fair Value Assets	486	710
Estimated Fair Value Liabilities	19	11
Derivatives Designated as Hedging Instruments | Foreign Operations Hedges [Member] | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Gross Notional Amount	4,306	4,097
Estimated Fair Value Assets	101	295
Estimated Fair Value Liabilities	11	11
Derivatives Designated as Hedging Instruments | Foreign Operations Hedges [Member] | Currency options
Derivatives, Fair Value [Line Items]
Gross Notional Amount	8,233	6,419
Estimated Fair Value Assets	385	415
Estimated Fair Value Liabilities	8	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivatives, Fair Value [Line Items]
Gross Notional Amount	346,077	372,885
Estimated Fair Value Assets	11,057	9,459
Estimated Fair Value Liabilities	5,668	5,669
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Interest rate swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	91,545	93,266
Estimated Fair Value Assets	5,353	4,570
Estimated Fair Value Liabilities	2,465	2,051
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Interest rate floors
Derivatives, Fair Value [Line Items]
Gross Notional Amount	34,155	55,645
Estimated Fair Value Assets	464	440
Estimated Fair Value Liabilities	172	199
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Interest rate caps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	52,763	49,128
Estimated Fair Value Assets	90	145
Estimated Fair Value Liabilities	1	1
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Interest rate futures
Derivatives, Fair Value [Line Items]
Gross Notional Amount	3,557	2,707
Estimated Fair Value Assets	9	4
Estimated Fair Value Liabilities	6	9
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Interest rate options
Derivatives, Fair Value [Line Items]
Gross Notional Amount	35,261	48,078
Estimated Fair Value Assets	1,666	1,241
Estimated Fair Value Liabilities	27	75
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Synthetic GICs
Derivatives, Fair Value [Line Items]
Gross Notional Amount	4,262	4,298
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	11,627	11,041
Estimated Fair Value Assets	855	447
Estimated Fair Value Liabilities	432	385
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Gross Notional Amount	12,191	13,206
Estimated Fair Value Assets	235	127
Estimated Fair Value Liabilities	387	791
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Currency futures
Derivatives, Fair Value [Line Items]
Gross Notional Amount	1,242	522
Estimated Fair Value Assets	1	2
Estimated Fair Value Liabilities	2	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Currency options
Derivatives, Fair Value [Line Items]
Gross Notional Amount	9,734	8,324
Estimated Fair Value Assets	531	585
Estimated Fair Value Liabilities	295	340
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Credit default swaps — purchased
Derivatives, Fair Value [Line Items]
Gross Notional Amount	2,711	2,830
Estimated Fair Value Assets	15	8
Estimated Fair Value Liabilities	49	34
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Credit default swaps — written
Derivatives, Fair Value [Line Items]
Gross Notional Amount	10,206	10,527
Estimated Fair Value Assets	190	181
Estimated Fair Value Liabilities	4	6
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Equity futures
Derivatives, Fair Value [Line Items]
Gross Notional Amount	6,248	6,073
Estimated Fair Value Assets	34	65
Estimated Fair Value Liabilities	7	2
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Equity index options
Derivatives, Fair Value [Line Items]
Gross Notional Amount	42,751	39,345
Estimated Fair Value Assets	1,411	1,426
Estimated Fair Value Liabilities	1,079	1,036
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Equity variance swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	24,449	24,598
Estimated Fair Value Assets	192	196
Estimated Fair Value Liabilities	664	639
Derivatives Not Designated or Not Qualifying as Hedging Instruments | TRRs
Derivatives, Fair Value [Line Items]
Gross Notional Amount	3,375	3,297
Estimated Fair Value Assets	11	22
Estimated Fair Value Liabilities	$ 78	$ 101