Allowance for Loan and Lease Losses Allowance for Loan and Lease Losses - Loss Sharing Arrangements (Details) - Loss sharing agreements - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Expected reimbursement from loss sharing partners, beginning balance	$ 379	$ 380
Amounts due from partners which reduced net charge-offs	(108)	(97)
Amounts estimated to be charged to partners which reduced provision for credit losses	171	105
Expected reimbursement from loss sharing partners, ending balance	$ 442	$ 388