CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 14,624	$ 13,967
Other comprehensive income (loss) before taxes:
Change in fair value of interest rate swap agreements	(4,878)	(1,489)
Provision for income tax benefit (expense) related to components of other comprehensive income (loss)	1,853	566
Other comprehensive income (loss)	(3,025)	(923)
Comprehensive income (loss)	$ 11,599	$ 13,044