CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net income (loss)	$ (70,503)	$ 9,125
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion, amortization and impairment	176,770	175,382
Dry holes and abandonments		46
Deferred income tax benefit	(11,616)	(23,800)
Stock-based compensation expense	7,211	6,855
Net gain on asset disposals	(2,445)	(2,916)
Tax expense on stock based compensation	(323)	(34)
Amortization of debt issuance costs	362	163
Changes in operating assets and liabilities:
Accounts receivable	37,362	176,672
Income taxes receivable/payable	(3,346)	112,711
Inventory and other assets	2,973	9,561
Accounts payable	(14,888)	(65,196)
Accrued expenses	(7,196)	5,559
Other liabilities	(628)	857
Net cash provided by operating activities	113,733	404,985
Cash flows from investing activities:
Purchases of property and equipment	(21,301)	(241,466)
Proceeds from disposal of assets	5,100	5,827
Net cash used in investing activities	(16,201)	(235,639)
Cash flows from financing activities:
Dividends paid	(14,712)	(14,640)
Debt issuance costs		(1,940)
Proceeds from long-term debt		200,000
Repayment of long-term debt	(10,000)	(2,500)
Proceeds from borrowings under revolving credit facility		54,000
Repayment of borrowings under revolving credit facility		(357,000)
Net cash used in financing activities	(24,712)	(122,080)
Effect of foreign exchange rate changes on cash	391	(3,361)
Net increase in cash and cash equivalents	73,211	43,905
Cash and cash equivalents at beginning of period	113,346	43,012
Cash and cash equivalents at end of period	186,557	86,917
Net cash (paid) received during the period for:
Interest, net of capitalized interest of $185 in 2016 and $1,667 in 2015	(3,773)	(783)
Income taxes	19,625	83,135
Non-cash investing and financing activities:
Net increase (decrease) in payables for purchases of property and equipment	14,063	(884)
Net decrease in deposits on equipment purchases	$ 3,972	$ 32,220