Commitments and Contingencies (Financial Instruments with Off Balance Sheet Risk) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Interest rate lock commitments [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Notional amount	$ 45,139	$ 49,502
Commitments to sell mortgage loans [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Notional amount	71,539	78,896
Interest rate swaps with customers [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Notional amount	545,049	428,723
Mirror swaps with counterparties [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Notional amount	545,049	428,723
Risk participation-in agreement [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Notional amount	34,052	28,460
Foreign exchange contract [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Notional amount	3,005	0
Interest rate swaps [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Notional amount	60,000	60,000
Commitments to Extend Credit [Member] | Commitments to extend credit on commerical loans [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract Amount	537,310	430,710
Commitments to Extend Credit [Member] | Commitments to extend credit on home equity lines [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract Amount	254,855	232,375
Commitments to Extend Credit [Member] | Commitments to extend credit on other loans [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract Amount	48,819	49,708
Commitments to Extend Credit [Member] | Commitments to extend credit on standby letters of credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract Amount	$ 6,666	$ 6,250