Investment Securities (Investments Classified by Contractual Maturity Date) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	$ 13,366	$ 15,135
Available-for-sale Securities, Amortized Cost Basis	13,378	15,167
Amortized cost of available-for-sale debt securities, Due in one year or less, Amount	713	644
Amortized cost of available-for-sale debt securities, Due after one year through five years, Amount	3,293	4,026
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Amortized Cost Basis	1,528	1,678
Amortized cost of available-for-sale debt securities, Due after ten years, Amount	6,538	7,631
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	12,210	14,076
Available-for-sale debt securities, Due in one year or less, Amount	715	646
Available-for-sale debt securities, Due after one year through five years, Amount	3,327	4,050
Available-for-sale debt securities, Due after five years through ten years, Amount	1,563	1,694
Available-for-sale debt securities, Due after ten years, Amount	6,605	7,686
Available-for-sale Securities, Amortized Cost Basis	12,072	13,979
Available-for-sale debt securities, Yield	2.80%	2.60%
Available-for-sale debt securities, Due in one year or less, Yield	2.50%	1.70%
Available-for-sale debt securities, Due after one year through five years, Yield	2.40%	2.40%
Available-for-sale debt securities, Due after five years through ten years, Yield	3.60%	3.50%
Available-for-sale debt securities, Due after ten years, Yield	2.80%	2.60%
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	877	1,546
Available-for-sale debt securities, Due in one year or less, Amount	151	231
Available-for-sale debt securities, Due after one year through five years, Amount	725	1,202
Available-for-sale debt securities, Due after five years through ten years, Amount	1	113
Available-for-sale debt securities, Due after ten years, Amount	0	0
Available-for-sale Securities, Amortized Cost Basis	874	1,535
Available-for-sale debt securities, Yield	0.80%	0.90%
Available-for-sale debt securities, Due in one year or less, Yield	0.80%	0.00%
Available-for-sale debt securities, Due after one year through five years, Yield	0.80%	0.90%
Available-for-sale debt securities, Due after five years through ten years, Yield	1.50%	2.20%
Available-for-sale debt securities, Due after ten years, Yield	0.00%	0.00%
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	0	1
Available-for-sale debt securities, Due in one year or less, Amount	0	0
Available-for-sale debt securities, Due after one year through five years, Amount		0
Available-for-sale debt securities, Due after five years through ten years, Amount	0	0
Available-for-sale debt securities, Due after ten years, Amount	0	1
Available-for-sale Securities, Amortized Cost Basis	0	1
Available-for-sale debt securities, Yield	0.00%	5.40%
Available-for-sale debt securities, Due in one year or less, Yield	0.00%	0.00%
Available-for-sale debt securities, Due after one year through five years, Yield	0.00%	0.00%
Available-for-sale debt securities, Due after five years through ten years, Yield	0.00%	0.00%
Available-for-sale debt securities, Due after ten years, Yield	0.00%	5.40%
Foreign Government Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	849	784
Available-for-sale debt securities, Due in one year or less, Amount	202	77
Available-for-sale debt securities, Due after one year through five years, Amount	419	506
Available-for-sale debt securities, Due after five years through ten years, Amount	221	201
Available-for-sale debt securities, Due after ten years, Amount	7	0
Available-for-sale Securities, Amortized Cost Basis	831	765
Available-for-sale debt securities, Yield	4.20%	4.40%
Available-for-sale debt securities, Due in one year or less, Yield	5.60%	7.70%
Available-for-sale debt securities, Due after one year through five years, Yield	4.00%	4.30%
Available-for-sale debt securities, Due after five years through ten years, Yield	3.10%	3.30%
Available-for-sale debt securities, Due after ten years, Yield	6.20%	0.00%
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	6,255	7,312
Available-for-sale debt securities, Due in one year or less, Amount	1	3
Available-for-sale debt securities, Due after one year through five years, Amount	0	2
Available-for-sale debt securities, Due after five years through ten years, Amount	209	189
Available-for-sale debt securities, Due after ten years, Amount	6,045	7,118
Available-for-sale Securities, Amortized Cost Basis	6,205	7,266
Available-for-sale debt securities, Yield	2.80%	2.50%
Available-for-sale debt securities, Due in one year or less, Yield	4.60%	4.80%
Available-for-sale debt securities, Due after one year through five years, Yield	0.00%	6.30%
Available-for-sale debt securities, Due after five years through ten years, Yield	2.40%	2.60%
Available-for-sale debt securities, Due after ten years, Yield	2.80%	2.50%
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	2,533	2,615
Available-for-sale debt securities, Due in one year or less, Amount	0	0
Available-for-sale debt securities, Due after one year through five years, Amount	1,568	1,599
Available-for-sale debt securities, Due after five years through ten years, Amount	527	574
Available-for-sale debt securities, Due after ten years, Amount	438	442
Available-for-sale Securities, Amortized Cost Basis	2,497	2,600
Available-for-sale debt securities, Yield	2.30%	2.10%
Available-for-sale debt securities, Due in one year or less, Yield	0.00%	0.00%
Available-for-sale debt securities, Due after one year through five years, Yield	2.10%	1.90%
Available-for-sale debt securities, Due after five years through ten years, Yield	2.00%	1.90%
Available-for-sale debt securities, Due after ten years, Yield	3.30%	3.20%
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	1,343	1,491
Available-for-sale debt securities, Due in one year or less, Amount	9	19
Available-for-sale debt securities, Due after one year through five years, Amount	615	741
Available-for-sale debt securities, Due after five years through ten years, Amount	604	606
Available-for-sale debt securities, Due after ten years, Amount	115	125
Available-for-sale Securities, Amortized Cost Basis	1,312	1,486
Available-for-sale debt securities, Yield	5.20%	4.90%
Available-for-sale debt securities, Due in one year or less, Yield	6.90%	4.90%
Available-for-sale debt securities, Due after one year through five years, Yield	4.50%	4.40%
Available-for-sale debt securities, Due after five years through ten years, Yield	6.20%	5.60%
Available-for-sale debt securities, Due after ten years, Yield	3.80%	4.70%
Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	353	327
Available-for-sale debt securities, Due in one year or less, Amount	352	316
Available-for-sale debt securities, Due after one year through five years, Amount	0	0
Available-for-sale debt securities, Due after five years through ten years, Amount	1	11
Available-for-sale debt securities, Due after ten years, Amount	0	0
Available-for-sale Securities, Amortized Cost Basis	$ 353	$ 326
Available-for-sale debt securities, Yield	1.50%	1.40%
Available-for-sale debt securities, Due in one year or less, Yield	1.40%	1.30%
Available-for-sale debt securities, Due after one year through five years, Yield	0.00%	0.00%
Available-for-sale debt securities, Due after five years through ten years, Yield	7.20%	4.60%
Available-for-sale debt securities, Due after ten years, Yield	0.00%	0.00%