Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash Flows From Operating Activities:
Net income (loss)	$ 82,878	$ (187,548)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	72,805	75,954
Amortization of debt issuance costs and discounts	3,323	1,876
Deferred income tax provision (benefit)	682	(12,913)
Equity-based compensation	10,107	(281)
Other, including loss on sale or disposal of assets, net	2,112	322
Changes in assets and liabilities:
Accounts receivable	(75,345)	26,349
Inventories	5,647	(2,655)
Prepaid expenses and other current assets	(3,896)	(5,294)
Accounts payable and accrued expenses	20,361	24,624
Accrued salaries, wages and benefits	8,464	(7,929)
Deferred revenue	121,815	36,234
Other accrued liabilities	845	(17,616)
Right-of-use assets and operating lease liabilities	224	253
Other assets and liabilities	(1,944)	298
Net cash provided by (used in) operating activities	248,078	(68,326)
Cash Flows From Investing Activities:
Capital expenditures	(44,981)	(53,699)
Net cash used in investing activities	(44,981)	(53,699)
Cash Flows From Financing Activities:
Proceeds from issuance of senior secured notes, net		222,335
Repayments of long-term debt	(7,752)	(7,752)
Proceeds from draws on revolving credit facility		272,500
Repayments of revolving credit facility		(11,500)
Purchase of treasury stock		(12,406)
Payment of tax withholdings on equity-based compensation through shares withheld	(12,528)	(3,314)
Exercise of stock options	4,032	218
Debt issuance costs		(1,089)
Other financing activities	(4,357)	(719)
Net cash (used in) provided by financing activities	(20,605)	458,273
Change in Cash and Cash Equivalents, including Restricted Cash	182,492	336,248
Cash and Cash Equivalents, including Restricted Cash—Beginning of period	435,225	40,925
Cash and Cash Equivalents, including Restricted Cash—End of period	617,717	377,173
Supplemental Disclosure of Noncash Investing and Financing Activities:
Capital expenditures in accounts payable	18,737	48,550
Other financing arrangements	$ 4,239	$ 2,837