Allowance for Loan and Lease Losses Allowance for Loan and Lease Losses - Loss Sharing Arrangements (Details) - Loss Sharing Agreement [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Expected reimbursement from loss sharing partners	$ 228	$ 194	$ 143	$ 140
Impact to net charge-offs	(229)	(189)	(164)
Impact to provision for credit losses	$ 263	$ 240	$ 167