Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 25,625	$ 27,122	$ 133,825
Other comprehensive income (loss), net of tax:
Change in fair value of interest rate swap agreements	(1,977)	(2,372)	234
Total other comprehensive income (loss)	(1,977)	(2,372)	234
Comprehensive income	$ 23,648	$ 24,750	$ 134,059