STATEMENTS OF COMPREHENSIVE INCOME STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net income	$ 17,457	$ 16,276	$ 135,587	$ 127,530
Other comprehensive income (loss), net of tax
Change in pension and postemployment benefit plan liability, net of tax of $(53), $(68), $(159) and $(487), respectively	160	203	480	326
Other comprehensive income, net of tax	160	203	480	326
Comprehensive income	$ 17,617	$ 16,479	$ 136,067	$ 127,856