Fair Value, Estimates for Financial Instruments Excluding those Recorded at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2015		Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Financial assets
Cash and due from banks	$ 19,687		$ 19,571	$ 20,635	$ 19,919
Federal funds sold, securities purchased under resale agreements and other short-term investments	232,247		258,429
Held-to-maturity securities	80,102		55,483
Mortgages held for sale	25,447	[1]	19,536
Loans held for sale	621	[1]	722
Loans	888,459	[1]	862,551
Nonmarketable equity investments (cost method)	6,861		7,033
Financial liabilities
Deposits	1,185,828		1,168,310
Short-term borrowings	82,963		63,518
Long-Term Debt	179,751		183,943
Carrying value [Member]
Financial assets
Cash and due from banks	19,687		19,571
Federal funds sold, securities purchased under resale agreements and other short-term investments	232,247		258,429
Held-to-maturity securities	80,102		55,483
Mortgages held for sale	3,908		3,971
Loans held for sale	621		721
Loans	859,330		832,671
Nonmarketable equity investments (cost method)	6,861		7,033
Financial liabilities
Deposits	1,185,828		1,168,310
Short-term borrowings	82,963		63,518
Long-Term Debt	179,743		183,934
Estimated fair value [Member]
Financial assets
Cash and due from banks	19,687		19,571
Federal funds sold, securities purchased under resale agreements and other short-term investments	232,247		258,429
Held-to-maturity securities	80,315		56,359
Mortgages held for sale	3,910		3,973
Loans held for sale	635		739
Loans	867,733		844,838
Nonmarketable equity investments (cost method)	8,208		8,377
Financial liabilities
Deposits	1,186,164		1,168,411
Short-term borrowings	82,963		63,518
Long-Term Debt	180,485		185,475
Estimated fair value [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets
Cash and due from banks	19,687		19,571
Federal funds sold, securities purchased under resale agreements and other short-term investments	7,991		8,991
Held-to-maturity securities	45,092		41,548
Mortgages held for sale	0		0
Loans held for sale	0		0
Loans	0		0
Nonmarketable equity investments (cost method)	0		0
Financial liabilities
Deposits	0		0
Short-term borrowings	0		0
Long-Term Debt	0		0
Estimated fair value [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets
Cash and due from banks	0		0
Federal funds sold, securities purchased under resale agreements and other short-term investments	223,913		249,438
Held-to-maturity securities	30,895		9,021
Mortgages held for sale	2,955		2,875
Loans held for sale	635		739
Loans	60,303		60,052
Nonmarketable equity investments (cost method)	36		0
Financial liabilities
Deposits	1,154,586		1,132,845
Short-term borrowings	82,963		63,518
Long-Term Debt	170,029		174,996
Estimated fair value [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets
Cash and due from banks	0		0
Federal funds sold, securities purchased under resale agreements and other short-term investments	343		0
Held-to-maturity securities	4,328		5,790
Mortgages held for sale	955		1,098
Loans held for sale	0		0
Loans	807,430		784,786
Nonmarketable equity investments (cost method)	8,172		8,377
Financial liabilities
Deposits	31,578		35,566
Short-term borrowings	0		0
Long-Term Debt	$ 10,456		$ 10,479

[1] Parenthetical amounts represent assets and liabilities for which we have elected the fair value option.