Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash Flows from Operating Activities:
Net Income (Loss)	$ (19,032)	$ 20,939	$ 98,821
Gain from discontinued operations, net of taxes	0	0	(14,211)
Adjustments to reconcile net income to net cash provided by operation activities -
Write-down of oil and gas properties	73,911	0	0
Depreciation, depletion, and amortization	252,043	247,178	221,230
Accretion of asset retirement obligation	6,181	5,121	4,570
Deferred income taxes	(6,766)	16,798	48,995
Stock-based compensation expenses	10,478	13,476	12,625
Other	(5,146)	976	2,143
Change in assets and liabilities-
(Increase) decrease in accounts receivable	(5,779)	3,235	(12,625)
Increase (decrease) in accounts payable and accrued liabilities	5,582	(2,102)	10,134
Increase (decrease) in income taxes payable	(224)	82	(73)
Increase in accrued interest	199	8,903	1,449
Cash provided by operating activities – continuing operations	311,447	314,606	373,058
Cash used by operating activities – discontinued operations	0	0	(2)
Net Cash Provided by Operating Activities	311,447	314,606	373,056
Cash Flows from Investing Activities:
Additions to property and equipment	(540,368)	(757,755)	(505,332)
Proceeds from the sale of property and equipment	6,991	528	50,284
Cash used in investing activities – continuing operations	(533,377)	(757,227)	(455,048)
Cash provided by investing activities – discontinued operations	0	0	5,000
Net Cash Used in Investing Activities	(533,377)	(757,227)	(450,048)
Cash Flows from Financing Activities:
Proceeds from long-term debt	0	157,500	247,890
Net proceeds from bank borrowings	225,600	39,400	0
Net proceeds from issuances of common stock	950	1,712	2,151
Purchase of treasury shares	(1,513)	(2,805)	(3,393)
Payments of debt issuance costs	0	(4,712)	(4,327)
Cash provided by financing activities – continuing operations	225,037	191,095	242,321
Cash provided by financing activities - discontinued operations	0	0	0
Net Cash Provided by Financing Activities	225,037	191,095	242,321
Net Increase (decrease) in Cash and Cash Equivalents	3,107	(251,526)	165,329
Cash and Cash Equivalents at Beginning of Period	170	251,696	86,367
Cash and Cash Equivalents at End of Period	3,277	170	251,696
Supplemental Disclosures of Cash Flows Information:
Cash paid during period for interest, net of amounts capitalized	67,070	46,911	32,078
Cash paid during period for income taxes	$ 217	$ 248	$ 1,770