Derivative Financial Instruments (Details 7) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net Derivative Gain (Loss) [Member]
Derivatives in cash flow hedging relationships Abstract
Amount and Location of Gains (Losses) Recognized In Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)
Cash Flow Hedges [Member]
Derivatives in cash flow hedging relationships Abstract
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	(44)	334	47	348
Cash Flow Hedges [Member] | Interest rate swaps [Member]
Derivatives in cash flow hedging relationships Abstract
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	(15)	119	47	123
Cash Flow Hedges [Member] | Foreign currency swaps [Member]
Derivatives in cash flow hedging relationships Abstract
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	(22)	31	(8)	30
Cash Flow Hedges [Member] | Forward Contracts [Member]
Derivatives in cash flow hedging relationships Abstract
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	(7)	184	8	195
Cash Flow Hedges [Member] | Credit forwards [Member]
Derivatives in cash flow hedging relationships Abstract
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	0	0	0	0
Cash Flow Hedges [Member] | Net Derivative Gain (Loss) [Member]
Derivatives in cash flow hedging relationships Abstract
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	1	(3)	0	1
Amount and Location of Gains (Losses) Recognized In Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	0	12	0	4
Cash Flow Hedges [Member] | Net Derivative Gain (Loss) [Member] | Interest rate swaps [Member]
Derivatives in cash flow hedging relationships Abstract
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	0	0	0	1
Amount and Location of Gains (Losses) Recognized In Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	0	0	0	0
Cash Flow Hedges [Member] | Net Derivative Gain (Loss) [Member] | Foreign currency swaps [Member]
Derivatives in cash flow hedging relationships Abstract
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	0	(3)	(1)	(1)
Amount and Location of Gains (Losses) Recognized In Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	(1)	0	(1)	0
Cash Flow Hedges [Member] | Net Derivative Gain (Loss) [Member] | Forward Contracts [Member]
Derivatives in cash flow hedging relationships Abstract
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	1	0	1	0
Amount and Location of Gains (Losses) Recognized In Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	1	12	1	4
Cash Flow Hedges [Member] | Net Derivative Gain (Loss) [Member] | Credit forwards [Member]
Derivatives in cash flow hedging relationships Abstract
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	0	0	0	1
Amount and Location of Gains (Losses) Recognized In Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	$ 0	$ 0	$ 0	$ 0