CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Comprehensive income:
Net income	$ 22,325	$ 24,221	$ 58,985	$ 54,477
Derivative instruments:
Reclassification of losses to net income, net of tax of $13, $13, $37 and $38, respectively	19	19	57	57
Other comprehensive income	19	19	57	57
Comprehensive income	$ 22,344	$ 24,240	$ 59,042	$ 54,534