Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Operating Activities:
Net income		$ 179,474	$ 98,104
Noncash items included in net income:
Depreciation and amortization		105,773	100,478
Deferred income taxes		5,086	10,607
Other, net		4,290	10,907
Changes in operating assets and liabilities, net		(26,937)	18,865
Net cash provided by operating activities		267,686	238,961
Investing Activities:
Acquisition of property and equipment		(154,884)	(205,307)
Proceeds from disposal of property and equipment		6,460	7,797
Other		(500)
Net cash used in investing activities		(148,924)	(197,510)
Financing Activities:
Repayments of revolving credit agreement		(36,410)	(303,108)
Borrowings of revolving credit agreement		36,410	302,179
Proceeds from stock option exercises		3,678	2,878
Shares withheld for taxes		(6,571)	(3,599)
Repayment of finance leases		(15,805)	(14,580)
Net cash used in financing activities		(18,698)	(16,230)
Net Increase in Cash, Cash Equivalents and Restricted Cash	[1]	100,064	25,221
Cash, Cash Equivalents and Restricted Cash, beginning of period	[1]	25,308	248
Cash, Cash Equivalents and Restricted Cash, end of period	[1]	$ 125,372	$ 25,469

[1] Cash, cash equivalents and restricted cash at the end of the period includes $3.7 million of restricted cash included in accounts receivable, net on the Condensed Consolidated Balance Sheet ending September 30, 2021.