Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended			4 Months Ended	5 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Apr. 23, 2021	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Operating activities:
Net loss				$ (1,961,989)	$ (52,475)		$ (1,105,366)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	$ 25,150		$ 75,330	92,758	43,885		243,208
Loss on impairment of assets				197,027			774,028
Reorganization items, net				1,587,392			22,107
Gain on disposition of assets	(767)		(479)	(5,486)	(943)		(4,132)
Deferred tax provision				(35,894)	9,122		(16,865)
Stock-based compensation expense					5,822		5,637
Contract liabilities, net				10,617	51,275		9,814
Contract assets, net				(742)	(974)		3,048
Deferred contract costs, net				(12,034)	(14,971)		(2,578)
Long-term employee remuneration programs				475	164		(4,803)
Collateral deposits					4,939		(18,262)
Other assets, noncurrent				2,685	(72)		(8,513)
Other liabilities, noncurrent				(371)	(1,354)		(3,240)
Other				2,683	965		2,964
Changes in operating assets and liabilities:
Accounts receivable				2,108	(40,668)		107,148
Prepaid expenses and other current assets				(2,791)	2		3,957
Accounts payable and accrued liabilities				29,302	(54,447)		(10,440)
Taxes payable				(5,804)	8,759		9,728
Net cash (used in) provided by operating activities				(100,064)	(40,971)		7,440
Investing activities:
Capital expenditures				(49,119)	(37,845)		(162,621)
Proceeds from sale of foreign bonds							5,915
Proceeds from disposition of assets, net of disposal costs				7,484	960		5,378
Net cash used in investing activities				(41,635)	(36,885)		(151,328)
Financing activities:
(Repayments of) borrowings under Predecessor credit facility				(442,034)			436,000
Borrowings on exit facilities				200,000	50,000
Repayments of exit facilities					(30,000)
Issuance of exit notes				75,000
Debt issuance costs and arrangement fees				(6,218)
Principal payments of finance lease liabilities					(6,011)
Net cash provided by (used in) financing activities				(173,252)	13,989		436,000
Net change in cash, cash equivalents and restricted cash				(314,951)	(63,867)		292,112
Cash, cash equivalents and restricted cash, beginning of period		$ 448,393		430,380	115,429	$ 430,380	156,281	$ 156,281
Cash, cash equivalents and restricted cash, end of period	$ 51,562	$ 430,380	$ 448,393	$ 115,429	$ 51,562	$ 51,562	$ 448,393	$ 430,380