Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Cash flows from operating activities:
Net income	$ (2,993)	$ 103,713
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation and amortization of property, equipment, and intangibles	200,408	172,149
Gain on sale of property and equipment	(6,651)	(20,879)
Impairments	3,982	0
Deferred income taxes	(13,673)	(1,316)
Non-cash lease expense	46,885	10,651
Gain on equity securities	(110)	(1,364)
Other adjustments to reconcile net (loss) income to net cash provided by operating activities	1,929	14,777
Increase (decrease) in cash resulting from changes in:
Trade receivables	17,995	35,614
Income tax receivable	7,542	28,753
Accounts payable	(25,564)	11,960
Accrued liabilities and claims accrual	(148,098)	8,194
Operating lease liabilities	(54,270)	(10,489)
Other assets and liabilities	9,893	(6,604)
Net cash provided by operating activities	37,275	345,159
Cash flows from investing activities:
Proceeds from maturities of held-to-maturity investments	530	3,620
Purchases of held-to-maturity investments	0	(525)
Proceeds from sale of property and equipment, including assets held for sale	50,605	59,345
Purchases of property and equipment	(191,905)	(260,339)
Expenditures on assets held for sale	(32)	(360)
Net cash, restricted cash, and equivalents invested in acquisitions	0	(275)
Other cash flows from investing activities	1,055	1,229
Net cash used in investing activities	(139,747)	(197,305)
Cash flows from financing activities:
Repayments of finance leases and long-term debt	(58,781)	(22,946)
Borrowings (repayments) on revolving lines of credit, net	135,000	(43,000)
Borrowings under accounts receivable securitization	12,000	0
Repayments of accounts receivable securitization	(85,000)	(35,000)
Proceeds from common stock issued	953	1,086
Dividends paid	(25,909)	(22,983)
Other cash flows from financing activities	(486)	(11,748)
Net cash used in financing activities	(22,223)	(134,591)
Net (decrease) increase in cash, restricted cash, and equivalents	(124,695)	13,263
Cash, restricted cash, and equivalents at beginning of period	469,686	385,345	$ 385,345
Cash, restricted cash, and equivalents at end of period	344,991	398,608	$ 469,686
Cash paid (received) during the period for:
Interest	41,264	21,920
Income taxes	(717)	1,295
Other Significant Noncash Transactions [Line Items]
Equipment acquired included in accounts payable	1,345	15,232
Right-of-use assets obtained in exchange for operating lease liabilities	5,102	16,281
Property and equipment obtained in exchange for finance lease liabilities	21,401	7,174
Financing provided to independent contractors for equipment sold
Other Significant Noncash Transactions [Line Items]
Other non-cash investing and financing activities	542	2,349
Transfers from property and equipment to assets held for sale [Member]
Other Significant Noncash Transactions [Line Items]
Other non-cash investing and financing activities	28,366	40,666
Property and equipment obtained in exchange for debt and finance lease liabilities from operating lease liabilities
Other Significant Noncash Transactions [Line Items]
Property and equipment obtained in exchange for finance lease liabilities	$ 20,025	$ 0