Loans and Allowance for Loan Losses - Loans in Consumer Portfolio Segment Based on Refreshed FICO Scores (Details) - Consumer - USD ($) $ in Millions		Sep. 30, 2017	Dec. 31, 2016
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements		$ 37,167	$ 33,099
Percentage of total		100.00%	100.00%
FICO Score 720 and Above
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements		$ 29,826	$ 25,970
Percentage of total		80.00%	78.00%
FICO Score Below 720
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements		$ 6,757	$ 6,574
Percentage of total		18.00%	20.00%
No FICO Available
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements	[1]	$ 584	$ 555
Percentage of total	[1]	2.00%	2.00%
Residential mortgage
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements		$ 33,859	$ 29,639
Residential mortgage | FICO Score 720 and Above
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements		27,548	23,598
Residential mortgage | FICO Score Below 720
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements		5,863	5,597
Residential mortgage | No FICO Available
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements	[1]	448	444
Home equity and other consumer loans
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements		3,308	3,460
Home equity and other consumer loans | FICO Score 720 and Above
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements		2,278	2,372
Home equity and other consumer loans | FICO Score Below 720
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements		894	977
Home equity and other consumer loans | No FICO Available
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements	[1]	$ 136	$ 111

[1] Represents loans for which management was not able to obtain an updated FICO score (e.g., due to recent profile changes).