Allowance for Loan and Lease Losses Allowance for Loan and Lease Losses - Loss Sharing Arrangements (Details) - Loss Sharing Agreement [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Expected reimbursement from loss sharing partners	$ 263	$ 219	$ 263	$ 219	$ 235	$ 228	$ 197	$ 194
Impact to net charge-offs	(67)	(53)	(132)	(105)
Impact to provision for credit losses	$ 95	$ 75	$ 167	$ 130