Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Statement of Other Comprehensive Income [Abstract]
Net Income:	$ 20,939	$ 98,821	$ 46,294
Other Comprehensive Income:
Unrealized gains (losses) related to price risk management transactions, before taxes	1,210	(520)	868
Provision (benefits) for income taxes	440	(190)	319
Unrealized gains (losses) related to price risk management transactions, net of taxes	770	(330)	549
Less: reclassification of (gains) losses on price risk management transactions to net income, before taxes	(1,210)	738	(732)
(Provision) benefit for income taxes	(440)	270	(269)
Reclassification of (gains) losses on price risk management transactions to net income, net of taxes	(770)	468	(463)
Other comprehensive income, before income taxes	0	218	136
Provision for income taxes	0	80	51
Other comprehensive income, net of taxes	0	138	85
Comprehensive Income	$ 20,939	$ 98,959	$ 46,379