Allowance for Credit Losses and Allowance for Unfunded Commitments and Letters of Credit (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease)	$ 67,600,000
Minimum loan balance of nonaccrual, collateral dependent loans considered for ACL	500,000		$ 500,000
Provision for credit losses	$ 33,500,000	$ 218,000	$ 75,000,000	$ 1,580,000