Consolidated statements of cash flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities
Net income (loss)	$ 4,405	$ (1,190)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation, depletion & amortization	55,750	43,916
Deferred income taxes	2,485	(746)
Gain on hedge reclassification adjustments	0	(10,003)
Non-hedge derivative losses	29,199	15,546
Gain on sale of assets	(84)	(95)
Other	492	1,197
Change in assets and liabilities
Accounts receivable	(15,762)	(210)
Inventories	(4,234)	(4,985)
Prepaid expenses and other assets	669	923
Accounts payable and accrued liabilities	2,303	1,879
Revenue distribution payable	(1,679)	699
Stock-based compensation	695	1,245
Net cash provided by operating activities	74,239	48,176
Cash flows from investing activities
Expenditures for property, plant, and equipment	(138,669)	(109,779)
Proceeds from asset dispositions	16,997	6,833
Settlement of non-hedge derivative instruments	(8,755)	9,896
Net cash used in investing activities	(130,427)	(93,050)
Cash flows from financing activities
Proceeds from long-term debt	50,603	24,868
Repayment of long-term debt	(3,783)	(1,752)
Principal payments under capital lease obligations	(570)	0
Net cash provided by financing activities	46,250	23,116
Net decrease in cash and cash equivalents	(9,938)	(21,758)
Cash and cash equivalents at beginning of period	48,595	29,819
Cash and cash equivalents at end of period	$ 38,657	$ 8,061