CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net Income	$ 93,983	$ 98,406	$ 92,556
Other comprehensive (loss) income, net of tax:
Reclassification of net gains on derivative instruments to net income	(730)	(732)	(730)
Reclassification of deferred tax liability on net gains on derivative instruments	0	0	(3,572)
Postretirement medical liability adjustment	963	(553)	(581)
Foreign currency translation	166	(54)	25
Total Other Comprehensive Income (Loss)	399	(1,339)	(4,858)
Comprehensive Income	$ 94,382	$ 97,067	$ 87,698