CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income (loss)	$ (318,634)	$ (294,486)	$ 162,664
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion, amortization and impairment	668,434	864,759	718,730
Impairment of goodwill		124,561
Dry holes and abandonments	58	1,224	550
Deferred income tax expense (benefit)	(152,160)	(99,873)	43,673
Stock-based compensation expense	28,324	28,510	27,032
Net gain on asset disposals	(14,771)	(10,613)	(15,781)
Tax expense related to stock-based compensation	(4,868)	(1,362)
Amortization of debt issuance costs	2,270	1,245	653
Changes in operating assets and liabilities:
Accounts receivable	72,327	440,884	(214,059)
Income taxes receivable/payable	30,379	49,895	(92,352)
Inventory and other assets	5,664	38,993	(6,390)
Accounts payable	12,024	(131,649)	86,621
Accrued expenses	(24,573)	(10,303)	12,838
Other liabilities	560	(2,348)	4,547
Net cash provided by operating activities	305,034	999,437	728,726
Cash flows from investing activities:
Acquisitions	155		(176,301)
Purchases of property and equipment	(119,799)	(743,776)	(1,052,341)
Proceeds from disposal of assets	21,889	20,814	33,233
Net cash used in investing activities	(97,755)	(722,962)	(1,195,409)
Cash flows from financing activities:
Purchases of treasury stock	(3,610)	(8,010)	(13,554)
Dividends paid	(23,579)	(58,775)	(58,288)
Tax benefit related to stock-based compensation			8,729
Proceeds from long-term debt		200,000
Repayment of long-term debt	(255,000)	(27,500)	(10,000)
Proceeds from borrowings under revolving credit facility	200,500	54,000	349,500
Repayment of borrowings under revolving credit facility	(200,500)	(357,000)	(46,500)
Debt issuance costs	(3,357)	(1,979)
Proceeds from exercise of stock options	268		30,842
Net cash provided by (used in) financing activities	(285,278)	(199,264)	260,729
Effect of foreign exchange rate changes on cash	(195)	(6,877)	(543)
Net increase (decrease) in cash and cash equivalents	(78,194)	70,334	(206,497)
Cash and cash equivalents at beginning of year	113,346	43,012	249,509
Cash and cash equivalents at end of year	35,152	113,346	43,012
Net cash (paid) received during the year for:
Interest, net of capitalized interest of $398 in 2016, $6,332 in 2015 and $6,883 in 2014	(36,551)	(33,452)	(27,813)
Income taxes	52,716	97,333	(125,953)
Non-cash investing and financing activities:
Net increase (decrease) in payables for purchases of property and equipment	28,926	(167,308)	122,148
Issuance of common stock for business acquisition	6,733
Net decrease (increase) in deposits on equipment purchases	$ 6,317	$ 90,012	$ (59,819)