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, 2015	Dec. 31, 2014	Dec. 31, 2013
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reduction in Charge-offs due to loss sharing agreements	$ 189	$ 164	$ 151
Reduction in provision for loan and lease losses	240	167	111
Expected reimbursement netted in allowance for loan losses	$ 194	$ 143	$ 141