Derivatives and Hedging Activities - Narrative (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($) derivative	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) derivative	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Interest Rate Swap [Member]
Derivative [Line Items]
Amount of gain (loss) related to change in fair value and other ineffectiveness	$ (100,000)	$ (200,000)	$ (4,700)	$ (1,300,000)
Fair value interest rate derivatives	1,800,000		1,800,000
Aggregate termination value had provisions been breached	1,800,000		1,800,000
Interest Rate Swap [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Gain in earnings related to ineffective portion	700,000		1,400,000
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Interest Expense [Member]
Derivative [Line Items]
Reclassified from AOCI into interest expense	36,000		300,000
Reclassified from AOCI interest expense in relation to previously settled interest rate derivatives	200,000		400,000
Derivative gain (loss) to be reclassified during next 12 months	$ 400,000		$ 400,000
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Number of derivative instruments associated with loans | derivative	4		7
Notional amount	$ 578,917,000		$ 578,917,000		$ 690,816,000
Four Interest Rate Swaps [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Notional amount	58,200,000		58,200,000
Seven Interest Rate Swaps [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Notional amount	$ 111,500,000		$ 111,500,000