Derivatives (Primary Risks) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Notional Amount	$ 401,112	$ 334,351
Estimated Fair Value Assets	9,301	13,777
Estimated Fair Value Liabilities	5,558	5,536
Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	34,202	28,866
Estimated Fair Value Assets	2,371	3,402
Estimated Fair Value Liabilities	915	594
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	9,456	8,584
Estimated Fair Value Assets	1,676	2,253
Estimated Fair Value Liabilities	184	175
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedges [Member] | Interest rate swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	6,452	5,397
Estimated Fair Value Assets	1,412	1,921
Estimated Fair Value Liabilities	61	90
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedges [Member] | Foreign currency swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	3,004	3,187
Estimated Fair Value Assets	264	332
Estimated Fair Value Liabilities	123	85
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	15,529	13,355
Estimated Fair Value Assets	524	1,063
Estimated Fair Value Liabilities	626	355
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedges [Member] | Interest rate swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	3,221	3,642
Estimated Fair Value Assets	174	705
Estimated Fair Value Liabilities	85	0
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedges [Member] | Interest rate forwards [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	495	675
Estimated Fair Value Assets	21	139
Estimated Fair Value Liabilities	0	0
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedges [Member] | Foreign currency swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	11,813	9,038
Estimated Fair Value Assets	329	219
Estimated Fair Value Liabilities	541	355
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedges [Member] | Credit forwards [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	0	0
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	0	0
Derivatives Designated as Hedging Instruments [Member] | Foreign Operations Hedges [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	9,217	6,927
Estimated Fair Value Assets	171	86
Estimated Fair Value Liabilities	105	64
Derivatives Designated as Hedging Instruments [Member] | Foreign Operations Hedges [Member] | Foreign currency forwards [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	3,448	2,552
Estimated Fair Value Assets	10	43
Estimated Fair Value Liabilities	94	61
Derivatives Designated as Hedging Instruments [Member] | Foreign Operations Hedges [Member] | Currency options [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	5,769	4,375
Estimated Fair Value Assets	161	43
Estimated Fair Value Liabilities	11	3
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	366,910	305,485
Estimated Fair Value Assets	6,930	10,375
Estimated Fair Value Liabilities	4,643	4,942
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	112,153	83,250
Estimated Fair Value Assets	3,584	5,201
Estimated Fair Value Liabilities	1,671	2,043
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate floors [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	63,064	56,246
Estimated Fair Value Assets	587	1,174
Estimated Fair Value Liabilities	456	837
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate caps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	34,960	49,465
Estimated Fair Value Assets	157	74
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	7,217	11,684
Estimated Fair Value Assets	3	1
Estimated Fair Value Liabilities	7	38
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate options [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	40,871	16,328
Estimated Fair Value Assets	335	640
Estimated Fair Value Liabilities	203	60
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Synthetic GICs [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	4,406	4,162
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	8,626	8,208
Estimated Fair Value Assets	143	199
Estimated Fair Value Liabilities	641	736
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Foreign currency forwards [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	11,873	9,202
Estimated Fair Value Assets	70	26
Estimated Fair Value Liabilities	143	288
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Currency futures [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	1,334	1,408
Estimated Fair Value Assets	2	4
Estimated Fair Value Liabilities	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Currency options [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	949	129
Estimated Fair Value Assets	43	1
Estimated Fair Value Liabilities	5	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Credit default swaps - purchased [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	3,511	3,674
Estimated Fair Value Assets	10	11
Estimated Fair Value Liabilities	38	34
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Credit default swaps - written [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	9,387	8,879
Estimated Fair Value Assets	119	79
Estimated Fair Value Liabilities	2	5
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Equity futures [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	5,430	7,008
Estimated Fair Value Assets	30	14
Estimated Fair Value Liabilities	4	132
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Equity Options [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	37,374	22,920
Estimated Fair Value Assets	1,699	2,825
Estimated Fair Value Liabilities	823	356
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Variance swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	21,961	19,830
Estimated Fair Value Assets	147	122
Estimated Fair Value Liabilities	530	310
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Total rate of return swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	3,794	3,092
Estimated Fair Value Assets	1	4
Estimated Fair Value Liabilities	$ 120	$ 103