CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income (loss)	$ (425,703,000)	$ (321,421,000)	$ 5,910,000
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion, amortization and impairment	1,003,873,000	916,318,000	783,341,000
Impairment of goodwill	17,800,000	211,129,000
Dry holes and abandonments	109,000	915,000	1,929,000
Deferred income tax benefit	(103,202,000)	(41,185,000)	(330,346,000)
Stock-based compensation expense	39,328,000	37,925,000	44,483,000
Net gain on asset disposals	(13,904,000)	(28,958,000)	(33,510,000)
Write-down of capacity reservation contract	12,673,000
Provision for bad debts	5,683,000	0	0
Loss on early debt extinguishment	24,023,000
Amortization of debt discount and issuance costs	937,000	830,000	346,000
Changes in operating assets and liabilities:
Accounts receivable	213,588,000	23,515,000	(239,482,000)
Income taxes receivable/payable	(3,353,000)	(1,555,000)	990,000
Inventory and other assets	29,394,000	(1,470,000)	(23,449,000)
Accounts payable	(77,686,000)	(69,453,000)	104,072,000
Accrued expenses	(18,218,000)	4,136,000	(14,190,000)
Other liabilities	(9,139,000)	(56,000)	617,000
Net cash provided by operating activities	696,203,000	730,670,000	300,711,000
Cash flows from investing activities:
Acquisitions, net of cash acquired	(13,000)	(14,211,000)	(501,954,000)
Purchases of property and equipment	(347,512,000)	(641,458,000)	(567,087,000)
Proceeds from disposal of assets and insurance claims	45,761,000	47,357,000	60,945,000
Collection of note receivable		23,760,000
Other investments			(2,520,000)
Net cash used in investing activities	(301,764,000)	(584,552,000)	(1,010,616,000)
Cash flows from financing activities:
Proceeds from equity offering			471,570,000
Purchases of treasury stock	(255,467,000)	(161,737,000)	(6,809,000)
Dividends paid	(32,428,000)	(30,589,000)	(16,315,000)
Proceeds from long-term debt	496,969,000	521,194,000
Repayment of long-term debt	(673,443,000)
Proceeds from borrowings under revolving credit facility		79,000,000	599,000,000
Repayment of borrowings under revolving credit facility		(347,000,000)	(331,000,000)
Debt issuance costs	(852,000)	(4,489,000)
Proceeds from exercise of stock options		485,000	123,000
Net cash provided by (used in) financing activities	(465,221,000)	56,864,000	716,569,000
Effect of foreign exchange rate changes on cash	(62,000)	(781,000)	1,012,000
Net increase (decrease) in cash and cash equivalents	(70,844,000)	202,201,000	7,676,000
Cash and cash equivalents at beginning of year	245,029,000	42,828,000	35,152,000
Cash and cash equivalents at end of year	174,185,000	245,029,000	42,828,000
Net cash (paid) received during the year for:
Interest, net of capitalized interest of $732 in 2019, $1,435 in 2018 and $1,175 in 2017	(76,870,000)	(41,184,000)	(34,953,000)
Income taxes	(1,452,000)	3,172,000	3,947,000
Non-cash investing and financing activities:
Receivable from property and equipment insurance		15,000,000
Net increase (decrease) in payables for purchases of property and equipment	(40,857,000)	36,241,000	17,228,000
Issuance of common stock for business acquisitions		2,932,000	1,226,890,000
Net decrease (increase) in deposits on equipment purchases	3,974,000	$ 4,311,000	$ (301,000)
Cashless exercise of stock options	$ 9,219,000