Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss) attributable to common stockholders	$ 16,878	$ (2,768)	$ 62,655	$ (13,223)
Other comprehensive income (loss):
Unrealized gain (loss) on derivatives, net of income taxes	421	(4,690)	(5,212)	(3,621)
Less: Interest expense on derivatives recognized into earnings, net of income taxes	(301)	(570)	(946)	(926)
Comprehensive income (loss)	$ 17,600	$ (6,888)	$ 58,389	$ (15,918)