Investment Securities (Investments Classified by Contractual Maturity Date) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	$ 13,770	$ 15,135
Available-for-sale Securities, Amortized Cost Basis	13,587	15,167
Amortized cost of available-for-sale debt securities, Due in one year or less, Amount	916	644
Amortized cost of available-for-sale debt securities, Due after one year through five years, Amount	3,339	4,026
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Amortized Cost Basis	1,682	1,678
Amortized cost of available-for-sale debt securities, Due after ten years, Amount	6,536	7,631
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	12,700	14,076
Available-for-sale debt securities, Due in one year or less, Amount	917	646
Available-for-sale debt securities, Due after one year through five years, Amount	3,388	4,050
Available-for-sale debt securities, Due after five years through ten years, Amount	1,738	1,694
Available-for-sale debt securities, Due after ten years, Amount	6,657	7,686
Available-for-sale Securities, Amortized Cost Basis	12,473	13,979
Available-for-sale debt securities, Yield	2.60%	2.60%
Available-for-sale debt securities, Due in one year or less, Yield	1.20%	1.70%
Available-for-sale debt securities, Due after one year through five years, Yield	2.30%	2.40%
Available-for-sale debt securities, Due after five years through ten years, Yield	3.30%	3.50%
Available-for-sale debt securities, Due after ten years, Yield	2.70%	2.60%
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	1,358	1,546
Available-for-sale debt securities, Due in one year or less, Amount	428	231
Available-for-sale debt securities, Due after one year through five years, Amount	731	1,202
Available-for-sale debt securities, Due after five years through ten years, Amount	199	113
Available-for-sale debt securities, Due after ten years, Amount	0	0
Available-for-sale Securities, Amortized Cost Basis	1,354	1,535
Available-for-sale debt securities, Yield	0.50%	0.90%
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	0.70%	0.90%
Available-for-sale debt securities, Due after five years through ten years, Yield	1.10%	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
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
Available-for-sale debt securities, Due after ten years, Amount		1
Available-for-sale Securities, Amortized Cost Basis	0	1
Available-for-sale debt securities, Yield		5.40%
Available-for-sale debt securities, Due in one year or less, Yield		0.00%
Available-for-sale debt securities, Due after one year through five years, Yield		0.00%
Available-for-sale debt securities, Due after five years through ten years, Yield		0.00%
Available-for-sale debt securities, Due after ten years, Yield		5.40%
Foreign Government Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	820	784
Available-for-sale debt securities, Due in one year or less, Amount	134	77
Available-for-sale debt securities, Due after one year through five years, Amount	433	506
Available-for-sale debt securities, Due after five years through ten years, Amount	249	201
Available-for-sale debt securities, Due after ten years, Amount	4	0
Available-for-sale Securities, Amortized Cost Basis	803	765
Available-for-sale debt securities, Yield	3.60%	4.40%
Available-for-sale debt securities, Due in one year or less, Yield	3.90%	7.70%
Available-for-sale debt securities, Due after one year through five years, Yield	3.80%	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	6.30%	0.00%
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	6,374	7,312
Available-for-sale debt securities, Due in one year or less, Amount	0	3
Available-for-sale debt securities, Due after one year through five years, Amount	4	2
Available-for-sale debt securities, Due after five years through ten years, Amount	182	189
Available-for-sale debt securities, Due after ten years, Amount	6,188	7,118
Available-for-sale Securities, Amortized Cost Basis	6,269	7,266
Available-for-sale debt securities, Yield	2.70%	2.50%
Available-for-sale debt securities, Due in one year or less, Yield	0.00%	4.80%
Available-for-sale debt securities, Due after one year through five years, Yield	5.30%	6.30%
Available-for-sale debt securities, Due after five years through ten years, Yield	2.30%	2.60%
Available-for-sale debt securities, Due after ten years, Yield	2.70%	2.50%
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	2,411	2,615
Available-for-sale debt securities, Due in one year or less, Amount	5	0
Available-for-sale debt securities, Due after one year through five years, Amount	1,583	1,599
Available-for-sale debt securities, Due after five years through ten years, Amount	486	574
Available-for-sale debt securities, Due after ten years, Amount	337	442
Available-for-sale Securities, Amortized Cost Basis	2,365	2,600
Available-for-sale debt securities, Yield	2.20%	2.10%
Available-for-sale debt securities, Due in one year or less, Yield	3.90%	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	3.20%	3.20%
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	1,404	1,491
Available-for-sale debt securities, Due in one year or less, Amount	18	19
Available-for-sale debt securities, Due after one year through five years, Amount	637	741
Available-for-sale debt securities, Due after five years through ten years, Amount	621	606
Available-for-sale debt securities, Due after ten years, Amount	128	125
Available-for-sale Securities, Amortized Cost Basis	1,349	1,486
Available-for-sale debt securities, Yield	5.20%	4.90%
Available-for-sale debt securities, Due in one year or less, Yield	3.90%	4.90%
Available-for-sale debt securities, Due after one year through five years, Yield	4.20%	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	5.70%	4.70%
Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	333	327
Available-for-sale debt securities, Due in one year or less, Amount	332	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	$ 333	$ 326
Available-for-sale debt securities, Yield	1.40%	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	4.40%	4.60%
Available-for-sale debt securities, Due after ten years, Yield	0.00%	0.00%