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
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Expected reimbursement from loss sharing partners	$ 235	$ 197	$ 228	$ 194
Impact to net charge-offs	(65)	(52)
Impact to provision for credit losses	$ 72	$ 55