Derivatives (Details 5) (Cash Flow Hedges [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Derivatives in cash flow hedging relationships
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	$ (215)	$ 1,552	$ (51)
Interest rate swaps [Member]
Derivatives in cash flow hedging relationships
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	(34)	1,023	13
Foreign currency swaps [Member]
Derivatives in cash flow hedging relationships
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	(164)	175	34
Interest rate forwards [Member]
Derivatives in cash flow hedging relationships
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	(17)	336	(117)
Credit forwards [Member]
Derivatives in cash flow hedging relationships
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	0	18	19
Net Derivative Gains (Losses) [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	25	(9)	(65)
Amount and Location of Gains (Losses) Recognized In Income (Loss) on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	(4)	5	1
Net Derivative Gains (Losses) [Member] | Interest rate swaps [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	1	(42)	0
Amount and Location of Gains (Losses) Recognized In Income (Loss) on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	2	1	3
Net Derivative Gains (Losses) [Member] | Foreign currency swaps [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	23	0	(79)
Amount and Location of Gains (Losses) Recognized In Income (Loss) on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	(6)	2	0
Net Derivative Gains (Losses) [Member] | Interest rate forwards [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	1	31	14
Amount and Location of Gains (Losses) Recognized In Income (Loss) on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	0	2	(2)
Net Derivative Gains (Losses) [Member] | Credit forwards [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	0	2	0
Amount and Location of Gains (Losses) Recognized In Income (Loss) on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	0	0	0
Net Investment Gains (Losses) [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	2	(3)	(4)
Net Investment Gains (Losses) [Member] | Interest rate swaps [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	4	1	0
Net Investment Gains (Losses) [Member] | Foreign currency swaps [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	(5)	(6)	(6)
Net Investment Gains (Losses) [Member] | Interest rate forwards [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	2	1	2
Net Investment Gains (Losses) [Member] | Credit forwards [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	1	1	0
Other Expenses [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	(3)	(9)	1
Other Expenses [Member] | Interest rate swaps [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	(3)	(10)	(1)
Other Expenses [Member] | Foreign currency swaps [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	1	2	2
Other Expenses [Member] | Interest rate forwards [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	(1)	(1)	0
Other Expenses [Member] | Credit forwards [Member]
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	$ 0	$ 0	$ 0