Derivatives - (Narrative) (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($) item	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) item	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) item
Derivative [Line Items]
Number of interest rate lock commitments | item					78
Number of forward contracts | item			13		11
Notional amount	$ 18,100		$ 18,100
Gain (loss) related to hedge ineffectiveness	400	$ (48)	800	$ (1,200)
Termination value of derivatives in net liability position	1,400		1,400		$ 1,300
Collateral Already Posted, Aggregate Fair Value	2,300		$ 2,300		800
Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Notional amount					13,800
Number OF Interest Rate Loack Commitments Member
Derivative [Line Items]
Number of interest rate lock commitments | item			81
Interest Rate Lock Commitments Notional Amount Member
Derivative [Line Items]
Notional amount	$ 14,000		$ 14,000
Forward Contract Notional [Member]
Derivative [Line Items]
Notional amount					$ 11,800
Designated as Hedging Instrument [Member] | Interest rate swap derivatives [Member]
Derivative [Line Items]
Number of interest rate swaps held | item	56		56		42
Notional amount	$ 398,100		$ 398,100		$ 313,000
Not Designated as Hedging Instrument, Economic Hedge [Member] | Interest rate swap derivatives [Member]
Derivative [Line Items]
Number of interest rate swaps held | item	45		45		36
Notional amount	$ 194,700		$ 194,700		$ 132,600