STATEMENTS OF COMPREHENSIVE INCOME STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income	$ 76,456	$ 64,743
Other comprehensive income (loss), net of tax
Change in pension and postemployment benefit plan liability, net of tax of $(80) and $(72), respectively	129	116
Other comprehensive income (loss), net of tax	129	116
Comprehensive income	$ 76,585	$ 64,859