Derivative Instruments (Details 1) (Asset and Liability Management Positions [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2012 Y	Dec. 31, 2011 Y
Fair Value Hedges [Member] | Foreign exchange cross-currency swaps [Member]
Asset and liability management derivative positions of the company
Notional Value, Assets		$ 688
Notional Value, Liabilities		432
Fair Value, Assets		17
Fair Value, Liabilities		23
Derivative Asset Average Remaining Maturity Period		5.17
Derivative Liability Average Remaining Maturity Period		5.17
Fair Value Hedges [Member] | Interest Rate Contracts [Member] | Receive fixed/pay floating swaps [Member]
Asset and liability management derivative positions of the company
Notional Value, Assets	500	500
Fair Value, Assets	30	27
Derivative Asset Average Remaining Maturity Period	3.59	4.09
Cash flow hedges [Member] | Interest Rate Contracts [Member] | Pay fixed/receive floating swaps [Member]
Asset and liability management derivative positions of the company
Notional Value, Liabilities	4,288	4,788
Fair Value, Liabilities	775	803
Derivative Liability Average Remaining Maturity Period	3.96	4.03
Cash flow hedges [Member] | Interest Rate Contracts [Member] | Receive fixed/pay floating swaps [Member]
Asset and liability management derivative positions of the company
Notional Value, Assets	7,000	750
Notional Value, Liabilities		6,250
Fair Value, Assets	33
Fair Value, Liabilities		6
Derivative Asset Average Remaining Maturity Period	2.35	2.75
Derivative Liability Average Remaining Maturity Period		2.86
Net investment hedges [Member] | Foreign exchange forward contracts [Member]
Asset and liability management derivative positions of the company
Notional Value, Assets		708
Fair Value, Assets		4
Derivative Asset Average Remaining Maturity Period		0.08
Other Economic Hedges [Member] | Credit Risk Contract [Member]
Asset and liability management derivative positions of the company
Notional Value, Assets	737	800
Notional Value, Liabilities	1,968	1,600
Fair Value, Assets	2	7
Fair Value, Liabilities	8	8
Derivative Asset Average Remaining Maturity Period	4.24	3.71
Derivative Liability Average Remaining Maturity Period	3.37	3.59
Other Economic Hedges [Member] | Equity Contract [Member]
Asset and liability management derivative positions of the company
Notional Value, Assets	60	54
Notional Value, Liabilities		10
Fair Value, Assets	3	1
Derivative Asset Average Remaining Maturity Period	1.87	1.05
Derivative Liability Average Remaining Maturity Period		0.64
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Receive fixed/pay floating swaps [Member]
Asset and liability management derivative positions of the company
Notional Value, Assets	3,775	2,625
Fair Value, Assets	4	9
Derivative Asset Average Remaining Maturity Period	10.23	10.21
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Futures and Forwards Buy [Member]
Asset and liability management derivative positions of the company
Notional Value, Assets	15,194	14,270
Notional Value, Liabilities	31	29
Fair Value, Assets	189	150
Derivative Asset Average Remaining Maturity Period	0.10	0.07
Derivative Liability Average Remaining Maturity Period	0.12	0.12
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Futures and Forwards Sell [Member]
Asset and liability management derivative positions of the company
Notional Value, Assets	1,465	231
Notional Value, Liabilities	18,263	14,415
Fair Value, Assets	2	1
Fair Value, Liabilities	135	134
Derivative Asset Average Remaining Maturity Period	0.09	0.15
Derivative Liability Average Remaining Maturity Period	0.11	0.11
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Purchased Option [Member]
Asset and liability management derivative positions of the company
Notional Value, Assets	1,500	1,250
Derivative Asset Average Remaining Maturity Period	0.07	0.07
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Written Option [Member]
Asset and liability management derivative positions of the company
Notional Value, Assets	6,165	4,421
Notional Value, Liabilities	12	11
Fair Value, Assets	145	80
Fair Value, Liabilities	1	1
Derivative Asset Average Remaining Maturity Period	0.13	0.10
Derivative Liability Average Remaining Maturity Period	0.17	0.13
Other Economic Hedges [Member] | Foreign exchange forward contracts [Member]
Asset and liability management derivative positions of the company
Notional Value, Assets	1,724	307
Notional Value, Liabilities	636	1,414
Fair Value, Assets	15	1
Fair Value, Liabilities	$ 5	$ 11
Derivative Asset Average Remaining Maturity Period	0.08	0.08
Derivative Liability Average Remaining Maturity Period	0.08	0.08