Derivatives and Hedging Activities (Details) - USD ($)			3 Months Ended		6 Months Ended
	Apr. 09, 2015	Feb. 03, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Derivative instruments and hedging activities disclosures
Amount of gain (loss) recorded in accumulated other comprehensive income			$ 448,000	$ (1,271,000)	$ (861,000)	$ (754,000)
Interest Rate Swap | Designated as Hedging Instrument
Derivative instruments and hedging activities disclosures
Interest rate as of reporting date (as a percent)		3.23%
Amount borrowed under term loan or revolving credit facility		$ 100,000,000
Debt Instrument, Term		5 years
Interest Rate Swap | Designated as Hedging Instrument | Cash Flow Hedging
Derivative instruments and hedging activities disclosures
Interest rate as of reporting date (as a percent)	2.93%
Amount borrowed under term loan or revolving credit facility	$ 75,000,000
Debt Instrument, Term	5 years
Amount of gain (loss) recorded in accumulated other comprehensive income			400,000	(1,300,000)	(900,000)	(800,000)
Amount reclassified to interest expense			500,000	$ 300,000	800,000	$ 500,000
Amount estimated to be reclassified as an increase to interest expense			1,900,000
Amount recognized in prepaid rent and other liabilities			800,000		800,000		$ 300,000
Amount recognized in other assets relating to outstanding derivatives			$ 500,000		$ 500,000
Interest Rate Swap | LIBOR | Designated as Hedging Instrument
Derivative instruments and hedging activities disclosures
Reference rate	one-month LIBOR