Derivatives (Primary Risks) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Gross Notional Amount	$ 389,525	$ 415,598
Estimated Fair Value Assets	12,494	13,452
Estimated Fair Value Liabilities	6,928	7,022
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Gross Notional Amount	45,894	42,713
Estimated Fair Value Assets	3,828	3,993
Estimated Fair Value Liabilities	1,731	1,353
Derivatives Designated as Hedging Instruments | Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Gross Notional Amount	11,076	11,087
Estimated Fair Value Assets	2,093	2,129
Estimated Fair Value Liabilities	325	412
Derivatives Designated as Hedging Instruments | Fair Value Hedges [Member] | Interest rate swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	5,914	6,044
Estimated Fair Value Assets	1,968	2,064
Estimated Fair Value Liabilities	18	21
Derivatives Designated as Hedging Instruments | Fair Value Hedges [Member] | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	3,077	2,708
Estimated Fair Value Assets	125	65
Estimated Fair Value Liabilities	225	100
Derivatives Designated as Hedging Instruments | Fair Value Hedges [Member] | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Gross Notional Amount	2,085	2,335
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	82	291
Derivatives Designated as Hedging Instruments | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Gross Notional Amount	23,990	21,110
Estimated Fair Value Assets	1,293	1,154
Estimated Fair Value Liabilities	1,390	930
Derivatives Designated as Hedging Instruments | Cash Flow Hedges [Member] | Interest rate swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	2,835	2,560
Estimated Fair Value Assets	386	528
Estimated Fair Value Liabilities	13	0
Derivatives Designated as Hedging Instruments | Cash Flow Hedges [Member] | Interest rate forwards
Derivatives, Fair Value [Line Items]
Gross Notional Amount	105	225
Estimated Fair Value Assets	19	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	21,050	18,325
Estimated Fair Value Assets	888	563
Estimated Fair Value Liabilities	1,377	930
Derivatives Designated as Hedging Instruments | Foreign Operations Hedges [Member]
Derivatives, Fair Value [Line Items]
Gross Notional Amount	10,828	10,516
Estimated Fair Value Assets	442	710
Estimated Fair Value Liabilities	16	11
Derivatives Designated as Hedging Instruments | Foreign Operations Hedges [Member] | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Gross Notional Amount	4,059	4,097
Estimated Fair Value Assets	130	295
Estimated Fair Value Liabilities	4	11
Derivatives Designated as Hedging Instruments | Foreign Operations Hedges [Member] | Currency options
Derivatives, Fair Value [Line Items]
Gross Notional Amount	6,769	6,419
Estimated Fair Value Assets	312	415
Estimated Fair Value Liabilities	12	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivatives, Fair Value [Line Items]
Gross Notional Amount	343,631	372,885
Estimated Fair Value Assets	8,666	9,459
Estimated Fair Value Liabilities	5,197	5,669
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Interest rate swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	92,199	93,266
Estimated Fair Value Assets	3,993	4,570
Estimated Fair Value Liabilities	1,829	2,051
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Interest rate floors
Derivatives, Fair Value [Line Items]
Gross Notional Amount	30,155	55,645
Estimated Fair Value Assets	328	440
Estimated Fair Value Liabilities	102	199
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Interest rate caps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	52,874	49,128
Estimated Fair Value Assets	85	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	2,997	2,707
Estimated Fair Value Assets	9	4
Estimated Fair Value Liabilities	12	9
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Interest rate options
Derivatives, Fair Value [Line Items]
Gross Notional Amount	35,507	48,078
Estimated Fair Value Assets	1,066	1,241
Estimated Fair Value Liabilities	78	75
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Synthetic GICs
Derivatives, Fair Value [Line Items]
Gross Notional Amount	4,211	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	11,354	11,041
Estimated Fair Value Assets	437	447
Estimated Fair Value Liabilities	437	385
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Gross Notional Amount	12,612	13,206
Estimated Fair Value Assets	114	127
Estimated Fair Value Liabilities	534	791
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Currency futures
Derivatives, Fair Value [Line Items]
Gross Notional Amount	1,013	522
Estimated Fair Value Assets	1	2
Estimated Fair Value Liabilities	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Currency options
Derivatives, Fair Value [Line Items]
Gross Notional Amount	9,920	8,324
Estimated Fair Value Assets	608	585
Estimated Fair Value Liabilities	319	340
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Credit default swaps — purchased
Derivatives, Fair Value [Line Items]
Gross Notional Amount	2,622	2,830
Estimated Fair Value Assets	12	8
Estimated Fair Value Liabilities	39	34
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Credit default swaps — written
Derivatives, Fair Value [Line Items]
Gross Notional Amount	10,594	10,527
Estimated Fair Value Assets	163	181
Estimated Fair Value Liabilities	5	6
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Equity futures
Derivatives, Fair Value [Line Items]
Gross Notional Amount	6,333	6,073
Estimated Fair Value Assets	47	65
Estimated Fair Value Liabilities	15	2
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Equity index options
Derivatives, Fair Value [Line Items]
Gross Notional Amount	42,856	39,345
Estimated Fair Value Assets	1,440	1,426
Estimated Fair Value Liabilities	1,104	1,036
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Equity variance swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	24,826	24,598
Estimated Fair Value Assets	286	196
Estimated Fair Value Liabilities	719	639
Derivatives Not Designated or Not Qualifying as Hedging Instruments | TRRs
Derivatives, Fair Value [Line Items]
Gross Notional Amount	3,558	3,297
Estimated Fair Value Assets	77	22
Estimated Fair Value Liabilities	$ 3	$ 101