Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Activities
Net income (loss)	$ (171,339)	$ 126,288	$ 99,659
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Loss from discontinued operations, net of income taxes	26,990	54,735	423
Depletion, depreciation, accretion and impairment	451,003	202,851	150,570
Deferred tax expense (recovery)	34,350	(28,865)	26,814
Non-cash stock-based compensation	5,451	8,002	10,999
Unrealized loss on financial instruments	9,383	0	0
Unrealized foreign exchange (gain) loss	(38,441)	(18,799)	17,150
Cash settlement of asset retirement obligation	(796)	(2,068)	0
Other loss	0	4,400	0
Other gain	(2,000)	0	(9,336)
Equity tax	(3,283)	(3,345)	(3,534)
Net change in assets and liabilities from operating activities of continuing operations
Accounts receivable and other long-term assets	(34,473)	58,955	(46,764)
Inventory	(2,891)	14,168	(18,253)
Prepaids	4	(2,458)	(416)
Accounts payable and accrued and other long-term liabilities	558	(8,754)	(10,178)
Taxes receivable and payable	(61,064)	84,687	(88,253)
Net cash provided by operating activities of continuing operations	213,452	489,797	128,881
Net cash (used in) provided by operating activities of discontinued operations	(4,792)	31,064	27,438
Net cash provided by operating activities	208,660	520,861	156,319
Investing Activities
(Increase) decrease in restricted cash	(96)	(1,590)	10,954
Additions to property, plant and equipment	(347,027)	(343,591)	(238,205)
Proceeds from oil and gas properties	0	55,524	0
Cash paid for acquisition	0	0	(35,495)
Net cash used in investing activities of continuing operations	(347,123)	(289,657)	(262,746)
Proceeds from sale of Argentina business unit, net of cash sold and transaction costs	42,755	0	0
Net cash used in investing activities of discontinued operations	(12,384)	(18,799)	(36,974)
Net cash provided by (used in) investing activities of discontinued operations	30,371	(18,799)	(36,974)
Net cash used in investing activities	(316,752)	(308,456)	(299,720)
Financing Activities
Proceeds from issuance of shares of Common Stock	11,140	3,771	4,340
Net cash provided by financing activities	11,140	3,771	4,340
Net (decrease) increase in cash and cash equivalents	(96,952)	216,176	(139,061)
Cash and cash equivalents, beginning of year	428,800	212,624	351,685
Cash and cash equivalents, end of year	331,848	428,800	212,624
Supplemental cash flow disclosures:
Cash paid for income taxes	101,179	51,183	143,498
Non-cash investing activities:
Net liabilities related to property, plant and equipment, end of year	113,874	75,580	75,393
Acquisition of marketable securities as proceeds from sale of Argentina business unit	$ 13,912	$ 0	$ 0