STATEMENTS OF COMPREHENSIVE INCOME STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net income	$ 64,743	$ 60,381
Other comprehensive income (loss), net of tax
Change in pension and postemployment benefit plan liability, net of tax of $(72) and $(88), respectively	116	140
Other comprehensive income (loss), net of tax	116	140
Comprehensive income	$ 64,859	$ 60,521