Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating Activities:
Net income	$ 188,669	$ 99,765
Noncash items included in net income:
Depreciation and amortization	76,896	70,031
Deferred income taxes	(907)	3,183
Other, net	3,862	5,640
Changes in operating assets and liabilities, net	(60,615)	(38,479)
Net cash provided by operating activities	207,905	140,140
Investing Activities:
Acquisition of property and equipment	(156,351)	(100,202)
Proceeds from disposal of property and equipment	1,060	236
Net cash used in investing activities	(155,291)	(99,966)
Financing Activities:
Repayments of revolving credit agreement	(1,000)	(27,614)
Borrowings of revolving credit agreement	1,000	27,614
Proceeds from stock option exercises	1,008	3,678
Shares withheld for taxes	(11,230)	(6,350)
Repayment of finance leases	(11,109)	(9,950)
Net cash used in financing activities	(21,331)	(12,622)
Net Increase in Cash and Cash Equivalents	31,283	27,552
Cash and Cash Equivalents, beginning of period	106,588	25,308
Cash and Cash Equivalents, end of period	$ 137,871	$ 52,860