STATEMENTS OF COMPREHENSIVE INCOME STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net income	$ 21,079	$ 17,457	$ 138,081	$ 135,587
Other comprehensive income (loss), net of tax
Change in pension and postemployment benefit plan liability, net of tax of $(75), $(53), $(149) and $(106), respectively	223	160	670	480
Other comprehensive income, net of tax	223	160	670	480
Comprehensive income	21,302	17,617	138,751	136,067
Pension and other postemployment benefit plans, tax	$ (75)	$ (53)	$ (224)	$ (159)