STATEMENTS OF COMPREHENSIVE INCOME STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Net income	$ 60,381	$ 59,076
Other comprehensive income (loss), net of tax
Change in pension and postretirement benefit plan liability, net of tax of $(88) and $2,124, respectively	140	(3,393)
Other comprehensive income (loss), net of tax	140	(3,393)
Comprehensive income	$ 60,521	$ 55,683