Loans and Leases (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Loans Receivable Held-for-sale, Amount	$ 1,500,000
Loans held for sale, at lower of cost or fair value	481,100	$ 0
Loan Receivable Held-For-Sale, Charge-offs	957	0	$ 0
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	10,800	8,000
Financing Receivable, Recorded Investment, Nonaccrual Status	155,784	170,599
Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	14,200	15,900
Financing Receivable Recorded Investment Thirty to Eighty Nine Days Past Due	3,200	3,000
Financing Receivable Recorded Investment Nonaccrual Status Current	138,400	151,700
Unfunded Commitments For Troubled Debt Restructurings	4,500	4,600
Cash Flow [Member]
Business Acquisition [Line Items]
Proceeds from Sale of Loans Held-for-sale	1,000,000
Cash Flow [Member]
Business Acquisition [Line Items]
Loan Receivable Held-For-Sale, Charge-offs	0
Non Purchased Credit Impaired Loans and Leases [Member]
Business Acquisition [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	155,784	170,599
Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	14,165	15,945
Financing Receivable Recorded Investment Thirty to Eighty Nine Days Past Due	$ 48,435	$ 31,569
Non Purchased Credit Impaired Loans and Leases [Member] | Credit Concentration Risk [Member]
Business Acquisition [Line Items]
Concentration Risk, Percentage	77.00%
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 120,000