Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Cash Flows from Operating Activities:
Net Income	$ 12,269	$ 15,587
Adjustments to reconcile net income to net cash provided by operation activities -
Depreciation, depletion, and amortization	135,741	120,229
Accretion of asset retirement obligation	2,801	3,254
Deferred income taxes	11,199	9,610
Stock-based compensation expenses	3,683	6,018
Other Noncash Income (Expense)	(2,439)	(6,321)
(Increase) Decrease in accounts receivable	1,360	(1,064)
Increase (decrease) in accounts payable and accrued liabilities	5,895	2,320
Increase (decrease) in income taxes payable	(150)	(178)
Increase (decrease) in accrued interest	(56)	76
Net Cash Provided by Operating Activities	170,303	149,531
Cash Flows from Investing Activities:
Additions to property and equipment	(208,979)	(265,317)
Proceeds from the sale of property and equipment	35	6,841
Net Cash Used in Investing Activities	(208,944)	(258,476)
Cash Flows from Financing Activities:
Proceeds from bank borrowings	257,100	568,200
Payments of bank borrowings	(221,100)	(447,600)
Net proceeds from issuances of common stock	824	946
Purchase of treasury shares	(896)	(1,433)
Net Cash Used in Financing Activities	35,928	120,113
Net Increase (Decrease) in Cash and Cash Equivalents	(2,713)	11,168
Cash and Cash Equivalents at Beginning of Period	3,277	170
Cash and Cash Equivalents at End of Period	564	11,338
Supplemental Disclosures of Cash Flows Information:
Cash paid during period for interest, net of amounts capitalized	36,031	32,708
Cash paid during period for income taxes	$ 150	$ 178