Accumulated Other Comprehensive Loss (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Components of comprehensive income
Net income	$ 4,492	$ 2,757
Reclassification to interest expense	216	294
Deferred income tax expense	(83)	(107)
Mark to market of interest rate hedges	13
Comprehensive income	4,638	2,944
Accumulated other comprehensive loss
Mark to market of interest rate hedges, net of tax benefit	(831)		(977)
Minimum pension liability adjustments, net of tax benefit	(521)		(521)
Accumulated other comprehensive loss	$ (1,352)		$ (1,498)