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, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Expected reimbursement from loss sharing partners, beginning balance	$ 380	$ 228	$ 194
Amounts due from partners which reduced net charge-offs	(382)	(285)	(229)
Amounts estimated to be charged to partners which reduced provision for credit losses	381	437	263
Expected reimbursement from loss sharing partners, ending balance	$ 379	$ 380	$ 228