STATEMENTS OF COMPREHENSIVE INCOME STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net income	$ 12,737	$ 7,371	$ 97,781	$ 79,828
Other comprehensive income (loss), net of tax
Change in pension and postretirement benefit plan liability, net of tax of $(72), $(88), $(217) and $(264), respectively	116	141	347	423
Other comprehensive income (loss), net of tax	116	141	347	423
Comprehensive income	$ 12,853	$ 7,512	$ 98,128	$ 80,251