Accumulated Other Comprehensive Loss (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Components of comprehensive income
Net income	$ 4,789	$ 3,947	$ 12,171	$ 12,631
Reclassification to interest expense	287	321	873	995
Deferred income tax expense	(81)	(59)	(310)	(193)
Mark to market of interest rate hedges	(64)	(158)	(21)	(464)
Comprehensive income	4,931	4,051	12,713	12,969
Accumulated other comprehensive loss
Mark to market of interest rate hedges, net of tax benefit	(1,132)		(1,132)		(1,674)
Minimum pension liability adjustments, net of tax benefit	(718)		(718)		(718)
Accumulated other comprehensive loss	$ (1,850)		$ (1,850)		$ (2,392)