Accumulated Other Comprehensive Loss (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Components of comprehensive income
Net income	$ 5,718	$ 4,626	$ 10,210	$ 7,382
Reclassification to interest expense	237	292	485	586
Deferred income tax expense	(79)	(122)	(163)	(229)
Mark to market of interest rate hedges	(19)	43	(37)	43
Comprehensive income	5,857	4,839	10,495	7,782
Accumulated other comprehensive loss
Mark to market of interest rate hedges, net of tax benefit	(692)		(692)		(977)
Minimum pension liability adjustments, net of tax benefit	(521)		(521)		(521)
Accumulated other comprehensive loss	$ (1,213)		$ (1,213)		$ (1,498)