Loans and Allowance for Loan Losses (Details 8) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2016	Dec. 31, 2015
Consumer
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements		$ 30,723	$ 30,436
Percentage of total		100.00%	100.00%
Consumer | 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		$ 23,713	$ 23,545
Percentage of total		77.00%	77.00%
Consumer | 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		$ 6,449	$ 6,306
Percentage of total		21.00%	21.00%
Consumer | No FICO Available
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements		$ 561	$ 585	[1]
Percentage of total	[1]	2.00%	2.00%
Consumer portfolio
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements		$ 30,584	$ 30,288
Consumer portfolio | 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		23,656	23,485
Consumer portfolio | 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		6,378	6,230
Consumer portfolio | 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]	550	573
Consumer portfolio | Residential mortgage
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements		27,260	27,109
Consumer portfolio | 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		21,311	21,209
Consumer portfolio | 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		5,482	5,412
Consumer portfolio | 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]	467	488
Consumer portfolio | 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		3,324	3,179
Consumer portfolio | 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		2,345	2,276
Consumer portfolio | 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		896	818
Consumer portfolio | 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]	83	85
Purchased credit-impaired loans | Consumer
Credit quality of consumer loans
Loan balances, excluding loans serviced by third parties and loans covered by FDIC loss share agreements		139	148
Purchased credit-impaired loans | Consumer | 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		57	60
Purchased credit-impaired loans | Consumer | 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		71	76
Purchased credit-impaired loans | Consumer | 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]	$ 11	$ 12

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