Loans and the Allowance for Loan Losses (Details) - Loans receivable on nonaccrual status - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Loans and the Allowance for Loan and Lease Losses (Details) - Loans receivable on nonaccrual status [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 49,715	$ 65,613
Commercial Portfolio Segment [Member]
Loans and the Allowance for Loan and Lease Losses (Details) - Loans receivable on nonaccrual status [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	29,205	47,363
Commercial Real Estate Portfolio Segment [Member]
Loans and the Allowance for Loan and Lease Losses (Details) - Loans receivable on nonaccrual status [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	15,657	12,757
Residential Real Estate Portfolio Segment [Member]
Loans and the Allowance for Loan and Lease Losses (Details) - Loans receivable on nonaccrual status [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 4,853	$ 5,493