Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities:
Net income	$ 354,857	$ 357,422	$ 253,235
Noncash items included in net income:
Depreciation and amortization	178,845	157,203	141,700
Allowance for credit losses	1,955	3,074	3,559
Deferred income taxes	10,070	21,634	4,319
Loss (gain) from property disposals, net	910	50	(3,894)
Stock-based compensation	11,636	8,827	8,703
Changes in operating assets and liabilities:
Accounts receivable	(23,391)	(16,624)	(63,415)
Accounts payable	10,752	(9,523)	16,729
Change in other assets and liabilities, net	32,311	(49,037)	21,656
Net cash provided by operating activities	577,945	473,026	382,592
Investing Activities:
Acquisition of property and equipment	(439,879)	(367,429)	(285,746)
Proceeds from disposal of property and equipment	2,727	1,917	8,398
Other	(11,544)	0	(500)
Net cash used in investing activities	(448,696)	(365,512)	(277,848)
Financing Activities:
Repayment of credit and private shelf agreements	0	(1,000)	(43,175)
Borrowing of credit and private shelf agreements	0	1,000	43,175
Proceeds from stock option exercises	4,875	4,511	3,678
Shares withheld for taxes	(9,216)	(11,752)	(6,571)
Repayment of finance leases	(14,520)	(19,471)	(20,571)
Other financing activity	(1,563)	0	0
Net cash used in financing activities	(20,424)	(26,712)	(23,464)
Net Increase in Cash and Cash Equivalents	108,825	80,802	81,280
Cash and cash equivalents, beginning of year	187,390	106,588	25,308
Cash and cash equivalents, end of year	$ 296,215	$ 187,390	$ 106,588