Loans and Allowance for Credit Losses, Allowance by Credit Impairment Methodology (Details) - USD ($) $ in Millions		Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Loans and Allowance for Credit Losses, by Credit Impairment Method [Abstract]
Allowance for Credit Losses, Collectively evaluated		$ 9,975		$ 9,945
Allowance for Credit Losses, Individually evaluated		2,171		2,593
Total allowance for credit losses		12,146	$ 12,287	12,540	$ 12,749	$ 12,668	$ 12,512
Financing Receivable, Collectively evaluated		922,588		928,496
Financing Receivable, Individually evaluated		20,562		22,377
Loans	[1]	957,423		967,604
Commercial Portfolio Segment [Member]
Loans and Allowance for Credit Losses, by Credit Impairment Method [Abstract]
Allowance for Credit Losses, Collectively evaluated		6,131		6,392
Allowance for Credit Losses, Individually evaluated		830		1,000
Total allowance for credit losses		6,961	7,142	7,394	7,441	7,348	6,872
Financing Receivable, Collectively evaluated		500,942		500,487
Financing Receivable, Individually evaluated		4,696		5,372
Loans		505,901		506,536
Consumer Portfolio Segment [Member]
Loans and Allowance for Credit Losses, by Credit Impairment Method [Abstract]
Allowance for Credit Losses, Collectively evaluated		3,844		3,553
Allowance for Credit Losses, Individually evaluated		1,341		1,593
Total allowance for credit losses		5,185	$ 5,145	5,146	$ 5,308	$ 5,320	$ 5,640
Financing Receivable, Collectively evaluated		421,646		428,009
Financing Receivable, Individually evaluated		15,866		17,005
Loans		451,522		461,068
PCI Loans Carrying Value [Member]
Loans and Allowance for Credit Losses, by Credit Impairment Method [Abstract]
Financing Receivable, Recorded Investment, Current		14,273		16,731
PCI Loans Carrying Value [Member] | Commercial Portfolio Segment [Member]
Loans and Allowance for Credit Losses, by Credit Impairment Method [Abstract]
Financing Receivable, Recorded Investment, Current		263		677
PCI Loans Carrying Value [Member] | Consumer Portfolio Segment [Member]
Loans and Allowance for Credit Losses, by Credit Impairment Method [Abstract]
Financing Receivable, Recorded Investment, Current		14,010		16,054
Allowance for Doubtful Accounts [Member]
Loans and Allowance for Credit Losses, by Credit Impairment Method [Abstract]
Total allowance for credit losses		0		2
Allowance for Doubtful Accounts [Member] | Commercial Portfolio Segment [Member]
Loans and Allowance for Credit Losses, by Credit Impairment Method [Abstract]
Total allowance for credit losses		0		2
Allowance for Doubtful Accounts [Member] | Consumer Portfolio Segment [Member]
Loans and Allowance for Credit Losses, by Credit Impairment Method [Abstract]
Total allowance for credit losses		$ 0		$ 0

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