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
Comprehensive income:
Net income	$ 31,008	$ 22,325	$ 77,613	$ 58,985
Derivative instruments:
Reclassification of losses to net income, net of tax of $9, $13, $26 and $37, respectively	23	19	69	57
Other comprehensive income	23	19	69	57
Comprehensive income	$ 31,031	$ 22,344	$ 77,682	$ 59,042