Securities - Amortized Cost, Fair Value, by Contract Maturity (Details 6) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 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	$ 48,823
Available-for-sale securities, maturities, due after 1 year through 5 years, amortized cost	62,071
Available-for-sale securities, maturities, due after 5 years through 10 years, amortized cost	49,274
Available-for-sale securities, maturities, due after 10 years, amortized cost	213,140
Available-for-sale securities, maturities, amortized cost, total	373,308		358,940
Available-for-sale securities, maturities, due in 1 year or less, fair value	48,822
Available-for-sale securities, maturities, due after 1 year through 5 years, fair value	62,547
Available-for-sale securities, maturities, due after 5 years through 10 years, fair value	49,845
Available-for-sale securities, maturities, due after 10 years, fair value	220,517
Available-for-sale securities, maturities, fair value, total	364,781	381,731
Available-for-sale securities, maturities, average yield, due in 1 year or less	1.67%
Available-for-sale securities, maturities, average yield, due after 1 year through 5 years	2.82%
Available-for-sale securities, maturities, average yield, due after 5 years through 10 years	3.06%
Available-for-sale securities, maturities, average yield, due after 10 years	3.45%
Available-for-sale securities, maturities, average yield, total	3.06%
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	8
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	1
Held-to-maturity securities, maturities, amortized cost, total	11
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	9
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	1
Held-to-maturity securities, maturities, fair value, total	12
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	6.89%
Held-to-maturity securities, maturities, average yield, due after 5 years through 10 years	6.73%
Held-to-maturity securities, maturities, average yield, due after 10 years	6.48%
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	4 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	2,486	2,486
Available-for-sale securities, equity maturities, amortized cost, total	2,486	2,486
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	2,505	2,505
Available-for-sale securities, equity maturities, fair value, total	2,505	2,505
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	0.39%	0.39%
Available-for-sale securities, equity maturities, average yield, total	0.39%	0.39%
Available-for-sale securities, maturities, amortized cost, total	2,486	2,486	2,693
Available-for-sale securities, maturities, fair value, total		2,505	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	48,823	48,823
Available-for-sale securities, due after 1 year through 5 years, amortized cost	62,071	62,071
Available-for-sale securities, due after 5 years through 10 years, amortized cost	49,274	49,274
Available-for-sale securities, due after 10 years, amortized cost	210,654	210,654
Available-for-sale Securities, Debt Maturities, Amortized Cost	370,822	370,822
Available-for-sale securities, due in 1 year or less, fair value	48,822	48,822
Available-for-sale securities, due after 1 year through 5 years, fair value	62,547	62,547
Available-for-sale securities, due after 5 years through 10 years, fair value	49,845	49,845
Available-for-sale securities, due after 10 years, fair value	218,012	218,012
Available-for-sale securities, fair value, total	379,226	379,226
Available-for-sale securities, average yield, due in 1 year or less	1.67%	1.67%
Available-for-sale securities, average yield, due after 1 year through 5 years	2.82%	2.82%
Available-for-sale securities, average yield, due after 5 years through 10 years	3.06%	3.06%
Available-for-sale securities, average yield, due after 10 years	3.48%	3.48%
Available-for-sale securities, average yield, total	3.08%	3.08%
Available-for-sale securities, maturities, amortized cost, total	370,822	370,822	356,247
Available-for-sale securities, maturities, fair value, total		379,226	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	15	15
Available-for-sale securities, due after 1 year through 5 years, amortized cost	8,283	8,283
Available-for-sale securities, due after 5 years through 10 years, amortized cost	8,605	8,605
Available-for-sale securities, due after 10 years, amortized cost	170,493	170,493
Available-for-sale Securities, Debt Maturities, Amortized Cost	187,396	187,396
Available-for-sale securities, due in 1 year or less, fair value	16	16
Available-for-sale securities, due after 1 year through 5 years, fair value	8,391	8,391
Available-for-sale securities, due after 5 years through 10 years, fair value	8,840	8,840
Available-for-sale securities, due after 10 years, fair value	176,179	176,179
Available-for-sale securities, fair value, total	193,426	193,426
Available-for-sale securities, average yield, due in 1 year or less	4.71%	4.71%
Available-for-sale securities, average yield, due after 1 year through 5 years	3.12%	3.12%
Available-for-sale securities, average yield, due after 5 years through 10 years	3.01%	3.01%
Available-for-sale securities, average yield, due after 10 years	3.44%	3.44%
Available-for-sale securities, average yield, total	3.41%	3.41%
Available-for-sale securities, maturities, amortized cost, total	187,396	187,396	180,838
Available-for-sale securities, maturities, fair value, total		193,426	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	7,302	7,302
Available-for-sale securities, due after 1 year through 5 years, amortized cost	2,707	2,707
Available-for-sale securities, due after 5 years through 10 years, amortized cost	1,411	1,411
Available-for-sale securities, due after 10 years, amortized cost	237	237
Available-for-sale Securities, Debt Maturities, Amortized Cost	11,657	11,657
Available-for-sale securities, due in 1 year or less, fair value	7,304	7,304
Available-for-sale securities, due after 1 year through 5 years, fair value	2,813	2,813
Available-for-sale securities, due after 5 years through 10 years, fair value	1,411	1,411
Available-for-sale securities, due after 10 years, fair value	239	239
Available-for-sale securities, fair value, total	11,767	11,767
Available-for-sale securities, average yield, due in 1 year or less	0.24%	0.24%
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	2.32%	2.32%
Available-for-sale securities, average yield, due after 10 years	2.06%	2.06%
Available-for-sale securities, average yield, total	1.00%	1.00%
Available-for-sale securities, maturities, amortized cost, total	11,657	11,657	8,184
Available-for-sale securities, maturities, fair value, total		11,767	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	61	61
Available-for-sale securities, due after 1 year through 5 years, amortized cost	322	322
Available-for-sale securities, due after 5 years through 10 years, amortized cost	1,065	1,065
Available-for-sale securities, due after 10 years, amortized cost	16,392	16,392
Available-for-sale Securities, Debt Maturities, Amortized Cost	17,840	17,840
Available-for-sale securities, due in 1 year or less, fair value	61	61
Available-for-sale securities, due after 1 year through 5 years, fair value	346	346
Available-for-sale securities, due after 5 years through 10 years, fair value	1,142	1,142
Available-for-sale securities, due after 10 years, fair value	17,793	17,793
Available-for-sale securities, fair value, total	19,342	19,342
Available-for-sale securities, average yield, due in 1 year or less	3.06%	3.06%
Available-for-sale securities, average yield, due after 1 year through 5 years	3.65%	3.65%
Available-for-sale securities, average yield, due after 5 years through 10 years	3.51%	3.51%
Available-for-sale securities, average yield, due after 10 years	4.73%	4.73%
Available-for-sale securities, average yield, total	4.63%	4.63%
Available-for-sale securities, maturities, amortized cost, total	17,840	17,840	15,404
Available-for-sale securities, maturities, fair value, total		19,342	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	2,926	2,926
Available-for-sale securities, due after 1 year through 5 years, amortized cost	118	118
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	3,044	3,044
Available-for-sale securities, due in 1 year or less, fair value	2,927	2,927
Available-for-sale securities, due after 1 year through 5 years, fair value	117	117
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	3,044	3,044
Available-for-sale securities, average yield, due in 1 year or less	4.25%	4.25%
Available-for-sale securities, average yield, due after 1 year through 5 years	2.52%	2.52%
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	4.18%	4.18%
Available-for-sale securities, maturities, amortized cost, total	3,044	3,044	3,017
Available-for-sale securities, maturities, fair value, total		3,044	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	19,037	19,037
Available-for-sale securities, due after 1 year through 5 years, amortized cost	19,001	19,001
Available-for-sale securities, due after 5 years through 10 years, amortized cost	7,971	7,971
Available-for-sale securities, due after 10 years, amortized cost	6,197	6,197
Available-for-sale Securities, Debt Maturities, Amortized Cost	52,206	52,206
Available-for-sale securities, due in 1 year or less, fair value	19,045	19,045
Available-for-sale securities, due after 1 year through 5 years, fair value	19,198	19,198
Available-for-sale securities, due after 5 years through 10 years, fair value	8,149	8,149
Available-for-sale securities, due after 10 years, fair value	6,295	6,295
Available-for-sale securities, fair value, total	52,687	52,687
Available-for-sale securities, average yield, due in 1 year or less	1.34%	1.34%
Available-for-sale securities, average yield, due after 1 year through 5 years	2.11%	2.11%
Available-for-sale securities, average yield, due after 5 years through 10 years	3.11%	3.11%
Available-for-sale securities, average yield, due after 10 years	3.81%	3.81%
Available-for-sale securities, average yield, total	2.18%	2.18%
Available-for-sale securities, maturities, amortized cost, total	52,206	52,206	44,944
Available-for-sale securities, maturities, fair value, total		52,687	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	19,481	19,481
Available-for-sale securities, due after 1 year through 5 years, amortized cost	28,345	28,345
Available-for-sale securities, due after 5 years through 10 years, amortized cost	12,706	12,706
Available-for-sale securities, due after 10 years, amortized cost	5	5
Available-for-sale Securities, Debt Maturities, Amortized Cost	60,537	60,537
Available-for-sale securities, due in 1 year or less, fair value	19,468	19,468
Available-for-sale securities, due after 1 year through 5 years, fair value	28,344	28,344
Available-for-sale securities, due after 5 years through 10 years, fair value	12,578	12,578
Available-for-sale securities, due after 10 years, fair value	5	5
Available-for-sale securities, fair value, total	60,395	60,395
Available-for-sale securities, average yield, due in 1 year or less	2.15%	2.15%
Available-for-sale securities, average yield, due after 1 year through 5 years	3.30%	3.30%
Available-for-sale securities, average yield, due after 5 years through 10 years	4.38%	4.38%
Available-for-sale securities, average yield, due after 10 years	5.01%	5.01%
Available-for-sale securities, average yield, total	3.15%	3.15%
Available-for-sale securities, maturities, amortized cost, total	60,537	60,537	63,607
Available-for-sale securities, maturities, fair value, total		60,395	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	1	1
Available-for-sale securities, due after 1 year through 5 years, amortized cost	3,295	3,295
Available-for-sale securities, due after 5 years through 10 years, amortized cost	17,516	17,516
Available-for-sale securities, due after 10 years, amortized cost	17,330	17,330
Available-for-sale Securities, Debt Maturities, Amortized Cost	38,142	38,142
Available-for-sale securities, due in 1 year or less, fair value	1	1
Available-for-sale securities, due after 1 year through 5 years, fair value	3,338	3,338
Available-for-sale securities, due after 5 years through 10 years, fair value	17,725	17,725
Available-for-sale securities, due after 10 years, fair value	17,501	17,501
Available-for-sale securities, fair value, total	$ 38,565	$ 38,565
Available-for-sale securities, average yield, due in 1 year or less	2.35%	2.35%
Available-for-sale securities, average yield, due after 1 year through 5 years	2.36%	2.36%
Available-for-sale securities, average yield, due after 5 years through 10 years	2.15%	2.15%
Available-for-sale securities, average yield, due after 10 years	2.61%	2.61%
Available-for-sale securities, average yield, total	2.38%	2.38%