Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities:
Net (loss) income	$ (357,214)	$ (180,272)	$ 18,346
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation	355,596	331,789	348,695
Loss on impairment of assets		27,225	99,313
Loss on extinguishment of senior notes			35,366
Restructuring and separation costs		1,478	14,146
Loss (gain) on disposition of assets	1,072	241	(10,500)
Deferred tax provision	(56,908)	(75,993)	(72,127)
Stock-based compensation expense	6,208	6,749	6,250
Contract liabilities, net	27,578	183	8,676
Contract assets, net	2,625	(6,221)
Deferred contract costs, net	59,141	22,765	46,337
Long-term employee remuneration programs	3,169	547	3,801
Other assets, noncurrent	52	(1,307)	(326)
Other liabilities, noncurrent	6,514	(3,217)	(963)
Other	2,380	1,013	3,907
Changes in operating assets and liabilities:
Accounts receivable	(37,832)	87,970	(11,049)
Prepaid expenses and other current assets	(1,170)	6,211	(1,291)
Accounts payable and accrued liabilities	3,897	(7,587)	19,803
Taxes payable	(6,019)	20,484	(14,576)
Net cash provided by operating activities	9,089	232,058	493,808
Investing activities:
Capital expenditures (including rig construction)	(326,090)	(222,406)	(139,581)
Proceeds from disposition of assets, net of disposal costs	16,217	70,067	15,196
Proceeds from sale and maturities of marketable securities	2,300,000	1,600,000	35
Purchase of marketable securities	(1,996,996)	(1,895,997)
Net cash used in investing activities	(6,869)	(448,336)	(124,350)
Financing activities:
Redemption of senior notes			(500,000)
Payment of debt extinguishment costs			(34,395)
Proceeds from issuance of senior notes			496,360
Repayment of short-term borrowings, net			(104,200)
Debt issuance costs and arrangement fees	(12)	(5,651)	(7,263)
Other		(35)	(156)
Net cash used in financing activities	(12)	(5,686)	(149,654)
Net change in cash and cash equivalents	2,208	(221,964)	219,804
Cash and cash equivalents, beginning of year	154,073	376,037	156,233
Cash and cash equivalents, end of year	$ 156,281	$ 154,073	$ 376,037