CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 59,780		$ 76,522		$ 125,387		$ 93,249
Reclassification to earnings	0	[1]	746	[1]	0	[1]	807	[1]
Pension liability adjustment	330		0		330		(3)
Total other comprehensive income, net of tax	330		746		330		804
Total comprehensive income	$ 60,110		$ 77,268		$ 125,717		$ 94,053

[1] Reclassification from accumulated other comprehensive loss (“AOCL”) related to de-designated hedges. As of December 31, 2013, all commodity derivative contracts that had been designated as cash flow hedges were settled and reclassified into earnings from AOCL.