Condensed Consolidated Statements Of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities:
Net income (loss)	$ 50,287	$ (488,585)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation	262,492	295,729
Loss on impairment of assets	71,268	678,145
Loss on extinguishment of senior notes	35,366
Gain on disposition of assets	(2,085)	(2,265)
Loss on sale of marketable securities		12,146
Deferred tax provision	(73,873)	(114,405)
Stock-based compensation expense	4,806	3,754
Deferred income, net	8,379	(23,381)
Deferred expenses, net	32,701	(1,099)
Other assets, noncurrent	(2,806)	(677)
Other liabilities, noncurrent	(212)	3,021
Other	2,387	1,997
Changes in operating assets and liabilities:
Accounts receivable	(25,743)	131,388
Prepaid expenses and other current assets	(4,831)	3,950
Accounts payable and accrued liabilities	17,787	(32,762)
Taxes payable	(9,288)	25,038
Net cash provided by operating activities	366,635	491,994
Investing activities:
Capital expenditures (including rig construction)	(100,613)	(598,236)
Proceeds from disposition of assets, net of disposal costs	4,017	169,038
Proceeds from sale and maturities of marketable securities	31	4,603
Net cash used in investing activities	(96,565)	(424,595)
Financing activities:
Redemption of senior notes	(500,000)
Payment of debt extinguishment costs	(34,395)
Proceeds from issuance of senior notes	496,360
Debt issuance costs and arrangement fees	(7,226)
Net repayment of short-term borrowings	(104,200)	(104,489)
Other	(156)	(609)
Net cash used in financing activities	(149,617)	(105,098)
Net change in cash and cash equivalents	120,453	(37,699)
Cash and cash equivalents, beginning of period	156,233	119,028
Cash and cash equivalents, end of period	$ 276,686	$ 81,329