Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net loss	$ (155,465)	$ (557,660)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation, depletion, amortization and accretion	222,400	268,709
Deferred income taxes	(61,322)	(137,753)
Reduction in value of assets		462,461
Stock based compensation expense	20,027	22,496
Other reconciling items, net	(1,603)	(10,146)
Changes in operating assets and liabilities:
Accounts receivable	(89,324)	121,044
Inventory and other current assets	(10,192)	(4,495)
Accounts payable	26,499	(22,779)
Accrued expenses	(11,202)	(60,033)
Income taxes	98,561	(5,062)
Other, net	(21,358)	20,920
Net cash provided by operating activities	17,021	97,702
Cash flows from investing activities:
Payments for capital expenditures	(56,649)	(67,402)
Decrease in cash held in escrow	30,600
Other	4,090	1,980
Net cash used in investing activities	(21,959)	(65,422)
Cash flows from financing activities:
Proceeds from revolving line of credit		325,000
Payments on revolving line of credit		(75,000)
Principal payments on long-term debt		(334,664)
Tax withholdings for vested restricted stock units	(8,298)	(3,480)
Cash dividends		(12,111)
Other	1,324	(4,139)
Net cash used in financing activities	(6,974)	(104,394)
Effect of exchange rate changes on cash	2,093	(6,056)
Net decrease in cash and cash equivalents	(9,819)	(78,170)
Cash and cash equivalents at beginning of period	187,591	564,017
Cash and cash equivalents at end of period	$ 177,772	$ 485,847