Derivative Instruments (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Interest Rate Derivatives [Abstract]
Number of interest rate swap contracts	3		3
aggregate notional amount	$ 102,000		$ 102,000		$ 103,600
Termination value of interest rate swap, including accrued interest	8,800		8,800
Interest Rate Cash Flow Hedges [Abstract]
Fair value of interest rate swaps	8,700		8,700		$ 8,500
Amount estimated to be reclassified from accumulated other comprehensive income as an increase to interest expense	1,200		1,200
Interest Rate Swap [Member] | Other Comprehensive Income (Loss) [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain related to the effective portion recognized in other comprehensive (loss) income	(1,570)	$ 299	(2,592)	$ (2,083)
Interest Rate Swap [Member] | Interest Expense [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain related to the effective portion subsequently reclassified to earnings	(350)	(367)	(1,053)	(1,093)
Amount of (loss) gain related to the ineffective portion	$ (51)	$ 13	$ (113)	$ (42)