Derivative Instruments and Hedging Activities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) Agreement	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount reclassified from AOCI, before tax	$ 609	$ 2,901	$ 0
Amount reclassified from AOCI, net of tax	372	1,772	0
Derivatives Not Designated as Hedging Instruments [Member]
Credit value adjustment recorded related to notional amount of derivatives outstanding and notional amount of risk participation agreements [Abstract]
Fair value adjustment	210	309
Derivatives Not Designated as Hedging Instruments [Member] | Interest Income [Member]
Gain or loss recognized in income on derivatives [Abstract]
Gain (loss) recognized in income on derivatives	179	95	33
Derivatives Not Designated as Hedging Instruments [Member] | Other Income [Member]
Gain or loss recognized in income on derivatives [Abstract]
Gain (loss) recognized in income on derivatives	$ 2,945	3,480	684
Derivatives Not Designated as Hedging Instruments [Member] | Interest Rate Derivatives [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of risk participation agreements held | Agreement	7
Credit value adjustment recorded related to notional amount of derivatives outstanding and notional amount of risk participation agreements [Abstract]
Notional amount	$ 481,185	371,101
Derivatives Not Designated as Hedging Instruments [Member] | Risk Participation Agreements [Member]
Credit value adjustment recorded related to notional amount of derivatives outstanding and notional amount of risk participation agreements [Abstract]
Notional amount	35,628	11,421
Derivatives Designated as Hedging Instruments [Member] | Interest Expense [Member]
Gain or loss recognized in income on derivatives [Abstract]
Gain (loss) recognized in income on derivatives	289	(70)	$ 0
Derivatives Designated as Hedging Instruments [Member] | Interest Rate Derivatives [Member]
Credit value adjustment recorded related to notional amount of derivatives outstanding and notional amount of risk participation agreements [Abstract]
Fair value adjustment	3,510	2,704
Notional amount	$ 250,000	$ 250,000