Loans (Narrative) (Details) $ in Thousands, loan in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) contract	Dec. 31, 2015 USD ($) loan contract	Dec. 31, 2014 USD ($) contract
Financing Receivable, Recorded Investment [Line Items]
Loans to related parties	$ 10,100	$ 10,000
Loans and Leases Receivable, Related Parties, Additions	1,200
Repayments on related party loans	1,100
Financing Receivable, Recorded Investment, Nonaccrual Status	27,756
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	1,900	$ 1,300	$ 2,200
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing, Number of Loans	0
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing, Number of Loans | loan		0.0
Loans and Leases Receivable, Nonaccrual of Interest, Commitments of Additional Funds	293	$ 2,900
Financing Receivable Modifications Additional Commitment To Lend	$ 508	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | contract	0	0	0
Loans Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans pledged to collateralize Federal Home Loan Bank Advances	$ 2,290,000	$ 2,220,000
Commercial Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans pledged to collateralize Federal Reserve Bank Borrowings	$ 54,200	$ 50,100