Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash Flows from Operating Activities:
Net Income	$ 13,931	$ 6,598
Adjustments to reconcile net income to net cash provided by operation activities -
Depreciation, depletion, and amortization	119,578	122,651
Accretion of asset retirement obligation	3,254	2,274
Deferred income taxes	8,670	4,399
Stock-based compensation expenses	6,018	7,181
Other	(6,024)	(1,277)
Decrease in accounts receivable	601	12,501
Increase (decrease) in accounts payable and accrued liabilities	3,605	(3,313)
Decrease in income taxes payable	(178)	(198)
Increase (decrease) in accrued interest	76	4,863
Net Cash Provided by Operating Activities	149,531	155,679
Cash Flows from Investing Activities:
Additions to property and equipment	(265,317)	(374,753)
Proceeds from the sale of property and equipment	6,841	284
Net Cash Used in Investing Activities	(258,476)	(374,469)
Cash Flows from Financing Activities:
Proceeds from Lines of Credit	120,600	0
Net proceeds from issuances of common stock	946	1,451
Purchase of treasury shares	(1,433)	(2,686)
Net Cash Used in Financing Activities	120,113	(1,235)
Net Decrease in Cash and Cash Equivalents	11,168	(220,025)
Cash and Cash Equivalents at Beginning of Period	170	251,696
Cash and Cash Equivalents at End of Period	11,338	31,671
Supplemental Disclosures of Cash Flows Information:
Cash paid during period for interest, net of amounts capitalized	32,708	20,698
Cash paid during period for income taxes	$ 178	$ 198