Securities - Amortized Cost, Fair Value, by Contract Maturity (Details 6) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012	Dec. 31, 2011
Amortized cost and estimated fair value by contractual maturity
Available-for-sale securities, maturities, due in 1 year or less, amortized cost	$ 38,776
Available-for-sale securities, maturities, due after 1 year through 5 years, amortized cost	62,588
Available-for-sale securities, maturities, due after 5 years through 10 years, amortized cost	54,331
Available-for-sale securities, maturities, due after 10 years, amortized cost	198,894
Available-for-sale securities, maturities, amortized cost, total	354,589		358,940
Available-for-sale securities, maturities, due in 1 year or less, fair value	38,802
Available-for-sale securities, maturities, due after 1 year through 5 years, fair value	63,574
Available-for-sale securities, maturities, due after 5 years through 10 years, fair value	55,413
Available-for-sale securities, maturities, due after 10 years, fair value	208,103
Available-for-sale securities, maturities, fair value, total	364,781	365,892
Available-for-sale securities, maturities, average yield, due in 1 year or less	1.69%
Available-for-sale securities, maturities, average yield, due after 1 year through 5 years	2.30%
Available-for-sale securities, maturities, average yield, due after 5 years through 10 years	2.09%
Available-for-sale securities, maturities, average yield, due after 10 years	3.47%
Available-for-sale securities, maturities, average yield, total	2.85%
Held-to-maturity securities, maturities, due in 1 year or less, amortized cost	0
Held-to-maturity securities, maturities, due after 1 year through 5 years, amortized cost	7
Held-to-maturity securities, maturities, due after 5 years through 10 years, amortized cost	2
Held-to-maturity securities, maturities, due after 10 years, amortized cost	0
Held-to-maturity securities, maturities, amortized cost, total	9
Held-to-maturity securities, maturities, due in 1 year or less, fair value	0
Held-to-maturity securities, maturities, due after 1 year through 5 years, fair value	8
Held-to-maturity securities, maturities, due after 5 years through 10 years, fair value	2
Held-to-maturity securities, maturities, due after 10 years, fair value	0
Held-to-maturity securities, maturities, fair value, total	10
Held-to-maturity securities, maturities, average yield, due in 1 year or less	0.00%
Held-to-maturity securities, maturities, average yield, due after 1 year through 5 years	6.88%
Held-to-maturity securities, maturities, average yield, due after 5 years through 10 years	6.61%
Held-to-maturity securities, maturities, average yield, due after 10 years	0.00%
Held-to-maturity securities, maturities, average yield, total	6.84%
Supplemental information
U S Government And Government Agencies And Authorities And U S Government Sponsored Enterprise Securities In Excess Of Ten Percent Of Stockholders Equity	10.00%
Non Agency Residential Collateralized Mortgage Obligations Estimated Duration	3 years
US Government Agencies And US Government sponsored Enterprises Residential Mortgage Backed Securities Estimated Duration	3 years
US Government Agencies And US Government-sponsored Enterprises, Residential Collateralized Mortgage Obligations, Estimated Duration	2 years
Minimum [Member]
Supplemental information
Due Period Of Mortgage Backed Securities And Collateralized Mortgage Obligations	10 years
Equity securities [Member]
Amortized cost and estimated fair value by contractual maturity
Available-for-sale securities, equity maturities, due in 1 year or less, amortized cost	0	0
Available-for-sale securities, equity maturities, due after 1 year through 5 years, amortized cost	0	0
Available-for-sale securities, equity maturities, due after 5 years through 10 years, amortized cost	0	0
Available-for-sale securities, equity maturities, due after 10 years, amortized cost	2,617	2,617
Available-for-sale securities, equity maturities, amortized cost, total	2,617	2,617
Available-for-sale securities, equity maturities, due in 1 year or less, fair value	0	0
Available-for-sale securities, equity maturities, due after 1 year through 5 years, fair value	0	0
Available-for-sale securities, equity maturities, due after 5 years through 10 years, fair value	0	0
Available-for-sale securities, equity maturities, due after 10 years, fair value	2,637	2,637
Available-for-sale securities, equity maturities, fair value, total	2,637	2,637
Available-for-sale securities, equity maturities, average yield, due in 1 year or less	0.00%	0.00%
Available-for-sale securities, equity maturities, average yield, due after 1 year through 5 years	0.00%	0.00%
Available-for-sale securities, equity maturities, average yield, due after 5 years through 10 years	0.00%	0.00%
Available-for-sale securities, equity maturities, average yield, due after 10 years	0.28%	0.28%
Available-for-sale securities, equity maturities, average yield, total	0.28%	0.28%
Available-for-sale securities, maturities, amortized cost, total	2,617	2,617	2,693
Available-for-sale securities, maturities, fair value, total		2,637	2,705
Debt Securities [Member]
Amortized cost and estimated fair value by contractual maturity
Available-for-sale securities, due in 1 year or less, amortized cost	38,776	38,776
Available-for-sale securities, due after 1 year through 5 years, amortized cost	62,588	62,588
Available-for-sale securities, due after 5 years through 10 years, amortized cost	54,331	54,331
Available-for-sale securities, due after 10 years, amortized cost	196,277	196,277
Available-for-sale Securities, Debt Maturities, Amortized Cost	351,972	351,972
Available-for-sale securities, due in 1 year or less, fair value	38,802	38,802
Available-for-sale securities, due after 1 year through 5 years, fair value	63,574	63,574
Available-for-sale securities, due after 5 years through 10 years, fair value	55,413	55,413
Available-for-sale securities, due after 10 years, fair value	205,466	205,466
Available-for-sale securities, fair value, total	363,255	363,255
Available-for-sale securities, average yield, due in 1 year or less	1.69%	1.69%
Available-for-sale securities, average yield, due after 1 year through 5 years	2.30%	2.30%
Available-for-sale securities, average yield, due after 5 years through 10 years	2.09%	2.09%
Available-for-sale securities, average yield, due after 10 years	3.51%	3.51%
Available-for-sale securities, average yield, total	2.87%	2.87%
Available-for-sale securities, maturities, amortized cost, total	351,972	351,972	356,247
Available-for-sale securities, maturities, fair value, total		363,255	362,076
Mortgage-backed securities [Member]
Amortized cost and estimated fair value by contractual maturity
Available-for-sale securities, due in 1 year or less, amortized cost	100	100
Available-for-sale securities, due after 1 year through 5 years, amortized cost	9,694	9,694
Available-for-sale securities, due after 5 years through 10 years, amortized cost	8,602	8,602
Available-for-sale securities, due after 10 years, amortized cost	156,029	156,029
Available-for-sale Securities, Debt Maturities, Amortized Cost	174,425	174,425
Available-for-sale securities, due in 1 year or less, fair value	101	101
Available-for-sale securities, due after 1 year through 5 years, fair value	9,933	9,933
Available-for-sale securities, due after 5 years through 10 years, fair value	8,925	8,925
Available-for-sale securities, due after 10 years, fair value	163,001	163,001
Available-for-sale securities, fair value, total	181,960	181,960
Available-for-sale securities, average yield, due in 1 year or less	1.84%	1.84%
Available-for-sale securities, average yield, due after 1 year through 5 years	2.01%	2.01%
Available-for-sale securities, average yield, due after 5 years through 10 years	2.58%	2.58%
Available-for-sale securities, average yield, due after 10 years	3.39%	3.39%
Available-for-sale securities, average yield, total	3.28%	3.28%
Available-for-sale securities, maturities, amortized cost, total	174,425	174,425	180,838
Available-for-sale securities, maturities, fair value, total		181,960	185,893
U.S. Treasury and government agencies [Member]
Amortized cost and estimated fair value by contractual maturity
Available-for-sale securities, due in 1 year or less, amortized cost	6,578	6,578
Available-for-sale securities, due after 1 year through 5 years, amortized cost	2,706	2,706
Available-for-sale securities, due after 5 years through 10 years, amortized cost	1,680	1,680
Available-for-sale securities, due after 10 years, amortized cost	98	98
Available-for-sale Securities, Debt Maturities, Amortized Cost	11,062	11,062
Available-for-sale securities, due in 1 year or less, fair value	6,579	6,579
Available-for-sale securities, due after 1 year through 5 years, fair value	2,799	2,799
Available-for-sale securities, due after 5 years through 10 years, fair value	1,678	1,678
Available-for-sale securities, due after 10 years, fair value	99	99
Available-for-sale securities, fair value, total	11,155	11,155
Available-for-sale securities, average yield, due in 1 year or less	0.19%	0.19%
Available-for-sale securities, average yield, due after 1 year through 5 years	2.29%	2.29%
Available-for-sale securities, average yield, due after 5 years through 10 years	1.32%	1.32%
Available-for-sale securities, average yield, due after 10 years	0.78%	0.78%
Available-for-sale securities, average yield, total	0.88%	0.88%
Available-for-sale securities, maturities, amortized cost, total	11,062	11,062	8,184
Available-for-sale securities, maturities, fair value, total		11,155	8,351
Obligations of U.S. states and municipalities [Member]
Amortized cost and estimated fair value by contractual maturity
Available-for-sale securities, due in 1 year or less, amortized cost	515	515
Available-for-sale securities, due after 1 year through 5 years, amortized cost	433	433
Available-for-sale securities, due after 5 years through 10 years, amortized cost	980	980
Available-for-sale securities, due after 10 years, amortized cost	18,503	18,503
Available-for-sale Securities, Debt Maturities, Amortized Cost	20,431	20,431
Available-for-sale securities, due in 1 year or less, fair value	515	515
Available-for-sale securities, due after 1 year through 5 years, fair value	471	471
Available-for-sale securities, due after 5 years through 10 years, fair value	1,047	1,047
Available-for-sale securities, due after 10 years, fair value	20,346	20,346
Available-for-sale securities, fair value, total	22,379	22,379
Available-for-sale securities, average yield, due in 1 year or less	0.91%	0.91%
Available-for-sale securities, average yield, due after 1 year through 5 years	5.87%	5.87%
Available-for-sale securities, average yield, due after 5 years through 10 years	4.21%	4.21%
Available-for-sale securities, average yield, due after 10 years	6.11%	6.11%
Available-for-sale securities, average yield, total	5.89%	5.89%
Available-for-sale securities, maturities, amortized cost, total	20,431	20,431	15,404
Available-for-sale securities, maturities, fair value, total		22,379	16,540
Certificates of Deposit [Member]
Amortized cost and estimated fair value by contractual maturity
Available-for-sale securities, due in 1 year or less, amortized cost	3,478	3,478
Available-for-sale securities, due after 1 year through 5 years, amortized cost	51	51
Available-for-sale securities, due after 5 years through 10 years, amortized cost	0	0
Available-for-sale securities, due after 10 years, amortized cost	0	0
Available-for-sale Securities, Debt Maturities, Amortized Cost	3,529	3,529
Available-for-sale securities, due in 1 year or less, fair value	3,480	3,480
Available-for-sale securities, due after 1 year through 5 years, fair value	54	54
Available-for-sale securities, due after 5 years through 10 years, fair value	0	0
Available-for-sale securities, due after 10 years, fair value	0	0
Available-for-sale securities, fair value, total	3,534	3,534
Available-for-sale securities, average yield, due in 1 year or less	5.22%	5.22%
Available-for-sale securities, average yield, due after 1 year through 5 years	3.28%	3.28%
Available-for-sale securities, average yield, due after 5 years through 10 years	0.00%	0.00%
Available-for-sale securities, average yield, due after 10 years	0.00%	0.00%
Available-for-sale securities, average yield, total	5.19%	5.19%
Available-for-sale securities, maturities, amortized cost, total	3,529	3,529	3,017
Available-for-sale securities, maturities, fair value, total		3,534	3,017
Non-U.S. government debt securities [Member]
Amortized cost and estimated fair value by contractual maturity
Available-for-sale securities, due in 1 year or less, amortized cost	19,595	19,595
Available-for-sale securities, due after 1 year through 5 years, amortized cost	22,347	22,347
Available-for-sale securities, due after 5 years through 10 years, amortized cost	15,224	15,224
Available-for-sale securities, due after 10 years, amortized cost	4,561	4,561
Available-for-sale Securities, Debt Maturities, Amortized Cost	61,727	61,727
Available-for-sale securities, due in 1 year or less, fair value	19,607	19,607
Available-for-sale securities, due after 1 year through 5 years, fair value	22,599	22,599
Available-for-sale securities, due after 5 years through 10 years, fair value	15,516	15,516
Available-for-sale securities, due after 10 years, fair value	4,708	4,708
Available-for-sale securities, fair value, total	62,430	62,430
Available-for-sale securities, average yield, due in 1 year or less	1.50%	1.50%
Available-for-sale securities, average yield, due after 1 year through 5 years	1.88%	1.88%
Available-for-sale securities, average yield, due after 5 years through 10 years	1.58%	1.58%
Available-for-sale securities, average yield, due after 10 years	1.68%	1.68%
Available-for-sale securities, average yield, total	1.67%	1.67%
Available-for-sale securities, maturities, amortized cost, total	61,727	61,727	44,944
Available-for-sale securities, maturities, fair value, total		62,430	45,265
Corporate Debt Securities [Member]
Amortized cost and estimated fair value by contractual maturity
Available-for-sale securities, due in 1 year or less, amortized cost	8,010	8,010
Available-for-sale securities, due after 1 year through 5 years, amortized cost	24,757	24,757
Available-for-sale securities, due after 5 years through 10 years, amortized cost	10,176	10,176
Available-for-sale securities, due after 10 years, amortized cost	160	160
Available-for-sale Securities, Debt Maturities, Amortized Cost	43,103	43,103
Available-for-sale securities, due in 1 year or less, fair value	8,018	8,018
Available-for-sale securities, due after 1 year through 5 years, fair value	25,094	25,094
Available-for-sale securities, due after 5 years through 10 years, fair value	10,323	10,323
Available-for-sale securities, due after 10 years, fair value	168	168
Available-for-sale securities, fair value, total	43,603	43,603
Available-for-sale securities, average yield, due in 1 year or less	1.95%	1.95%
Available-for-sale securities, average yield, due after 1 year through 5 years	2.76%	2.76%
Available-for-sale securities, average yield, due after 5 years through 10 years	2.58%	2.58%
Available-for-sale securities, average yield, due after 10 years	2.27%	2.27%
Available-for-sale securities, average yield, total	2.56%	2.56%
Available-for-sale securities, maturities, amortized cost, total	43,103	43,103	63,607
Available-for-sale securities, maturities, fair value, total		43,603	62,176
Asset-backed securities
Amortized cost and estimated fair value by contractual maturity
Available-for-sale securities, due in 1 year or less, amortized cost	500	500
Available-for-sale securities, due after 1 year through 5 years, amortized cost	2,600	2,600
Available-for-sale securities, due after 5 years through 10 years, amortized cost	17,669	17,669
Available-for-sale securities, due after 10 years, amortized cost	16,926	16,926
Available-for-sale Securities, Debt Maturities, Amortized Cost	37,695	37,695
Available-for-sale securities, due in 1 year or less, fair value	502	502
Available-for-sale securities, due after 1 year through 5 years, fair value	2,624	2,624
Available-for-sale securities, due after 5 years through 10 years, fair value	17,924	17,924
Available-for-sale securities, due after 10 years, fair value	17,144	17,144
Available-for-sale securities, fair value, total	$ 38,194	$ 38,194
Available-for-sale securities, average yield, due in 1 year or less	1.11%	1.11%
Available-for-sale securities, average yield, due after 1 year through 5 years	1.98%	1.98%
Available-for-sale securities, average yield, due after 5 years through 10 years	1.95%	1.95%
Available-for-sale securities, average yield, due after 10 years	2.23%	2.23%
Available-for-sale securities, average yield, total	2.07%	2.07%