CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Comprehensive income:
Net income	$ 24,221	$ 26,232	$ 54,477	$ 61,011
Derivative instruments:
Reclassification of losses to net income, net of tax of $13, $13, $38 and $37, 2016 and 2015, respectively	19	19	57	57
Other comprehensive income	19	19	57	57
Comprehensive income	$ 24,240	$ 26,251	$ 54,534	$ 61,068