Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss) available to common stockholders	$ (2,896)	$ 28,007	$ 32,545	$ 56,235
Other comprehensive income:
Unrealized gain (loss) on derivatives, net of income taxes	8,495	(543)	30,328	(5,016)
Less interest income (expense) on derivatives recognized into earnings, net of income taxes	697	(138)	2,352	(1,042)
Comprehensive income	$ 4,902	$ 27,602	$ 60,521	$ 52,261