Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss) attributable to common stockholders	$ 32,643	$ 7,540	$ 45,777	$ (10,455)
Other comprehensive income (loss):
Unrealized gain (loss) on derivatives, net of income taxes	165	2,861	(5,633)	1,069
Less interest expense on derivatives recognized into earnings, net of income taxes	(120)	(356)	(645)	(356)
Comprehensive income (loss)	$ 32,928	$ 10,757	$ 40,789	$ (9,030)