Derivatives (Primary Risks) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Gross Notional Amount	$ 389,787	$ 415,598
Estimated Fair Value Assets	15,515	13,452
Estimated Fair Value Liabilities	7,354	7,022
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Gross Notional Amount	45,963	42,713
Estimated Fair Value Assets	4,476	3,993
Estimated Fair Value Liabilities	2,054	1,353
Derivatives Designated as Hedging Instruments | Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Gross Notional Amount	11,123	11,087
Estimated Fair Value Assets	2,381	2,129
Estimated Fair Value Liabilities	287	412
Derivatives Designated as Hedging Instruments | Fair Value Hedges [Member] | Interest rate swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	5,922	6,044
Estimated Fair Value Assets	2,294	2,064
Estimated Fair Value Liabilities	19	21
Derivatives Designated as Hedging Instruments | Fair Value Hedges [Member] | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	3,116	2,708
Estimated Fair Value Assets	87	65
Estimated Fair Value Liabilities	230	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	38	291
Derivatives Designated as Hedging Instruments | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Gross Notional Amount	24,205	21,110
Estimated Fair Value Assets	1,724	1,154
Estimated Fair Value Liabilities	1,748	930
Derivatives Designated as Hedging Instruments | Cash Flow Hedges [Member] | Interest rate swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	2,488	2,560
Estimated Fair Value Assets	557	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	105	225
Estimated Fair Value Assets	26	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	21,612	18,325
Estimated Fair Value Assets	1,141	563
Estimated Fair Value Liabilities	1,748	930
Derivatives Designated as Hedging Instruments | Foreign Operations Hedges [Member]
Derivatives, Fair Value [Line Items]
Gross Notional Amount	10,635	10,516
Estimated Fair Value Assets	371	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	3,866	4,097
Estimated Fair Value Assets	78	295
Estimated Fair Value Liabilities	7	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	293	415
Estimated Fair Value Liabilities	12	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivatives, Fair Value [Line Items]
Gross Notional Amount	343,824	372,885
Estimated Fair Value Assets	11,039	9,459
Estimated Fair Value Liabilities	5,300	5,669
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Interest rate swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	89,232	93,266
Estimated Fair Value Assets	5,305	4,570
Estimated Fair Value Liabilities	2,518	2,051
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Interest rate floors
Derivatives, Fair Value [Line Items]
Gross Notional Amount	27,337	55,645
Estimated Fair Value Assets	395	440
Estimated Fair Value Liabilities	93	199
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Interest rate caps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	54,018	49,128
Estimated Fair Value Assets	75	145
Estimated Fair Value Liabilities	2	1
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Interest rate futures
Derivatives, Fair Value [Line Items]
Gross Notional Amount	3,874	2,707
Estimated Fair Value Assets	3	4
Estimated Fair Value Liabilities	9	9
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Interest rate options
Derivatives, Fair Value [Line Items]
Gross Notional Amount	35,336	48,078
Estimated Fair Value Assets	1,623	1,241
Estimated Fair Value Liabilities	20	75
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Synthetic GICs
Derivatives, Fair Value [Line Items]
Gross Notional Amount	4,223	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	11,062	11,041
Estimated Fair Value Assets	669	447
Estimated Fair Value Liabilities	465	385
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Gross Notional Amount	12,158	13,206
Estimated Fair Value Assets	220	127
Estimated Fair Value Liabilities	230	791
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Currency futures
Derivatives, Fair Value [Line Items]
Gross Notional Amount	2,495	522
Estimated Fair Value Assets	1	2
Estimated Fair Value Liabilities	1	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Currency options
Derivatives, Fair Value [Line Items]
Gross Notional Amount	9,443	8,324
Estimated Fair Value Assets	502	585
Estimated Fair Value Liabilities	229	340
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Credit default swaps — purchased
Derivatives, Fair Value [Line Items]
Gross Notional Amount	2,274	2,830
Estimated Fair Value Assets	27	8
Estimated Fair Value Liabilities	34	34
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Credit default swaps — written
Derivatives, Fair Value [Line Items]
Gross Notional Amount	10,458	10,527
Estimated Fair Value Assets	58	181
Estimated Fair Value Liabilities	11	6
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Equity futures
Derivatives, Fair Value [Line Items]
Gross Notional Amount	6,748	6,073
Estimated Fair Value Assets	23	65
Estimated Fair Value Liabilities	82	2
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Equity index options
Derivatives, Fair Value [Line Items]
Gross Notional Amount	46,447	39,345
Estimated Fair Value Assets	1,681	1,426
Estimated Fair Value Liabilities	920	1,036
Derivatives Not Designated or Not Qualifying as Hedging Instruments | Equity variance swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	24,872	24,598
Estimated Fair Value Assets	209	196
Estimated Fair Value Liabilities	682	639
Derivatives Not Designated or Not Qualifying as Hedging Instruments | TRRs
Derivatives, Fair Value [Line Items]
Gross Notional Amount	3,847	3,297
Estimated Fair Value Assets	248	22
Estimated Fair Value Liabilities	$ 4	$ 101