Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Cash flows from operating activities:
Net income	$ 19,893	$ 62,904	$ 16,900	$ 166,617
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation and amortization of property, equipment, and intangibles			397,802	345,035
Gain on sale of property and equipment			(12,604)	(35,180)
Impairments	5,877	0	9,859	0
Deferred income taxes			(30,970)	(8,002)
Non-cash lease expense			82,263	22,138
Gain on equity securities			(288)	(1,870)
Other adjustments to reconcile net income to net cash provided by operating activities			1,324	36,277
Increase (decrease) in cash resulting from changes in:
Trade receivables			32,115	126,429
Income tax receivable			26,549	41,671
Accounts payable			(39,647)	5,072
Accrued liabilities and claims accrual			(132,943)	46,408
Operating lease liabilities			(91,427)	(22,187)
Other assets and liabilities			51,767	(218)
Net cash provided by operating activities			310,700	722,190
Cash flows from investing activities:
Proceeds from maturities of held-to-maturity investments			530	3,620
Purchases of held-to-maturity investments			0	(30)
Proceeds from sale of property and equipment, including assets held for sale			114,033	98,755
Purchases of property and equipment			(372,661)	(517,856)
Expenditures on assets held for sale			(79)	(634)
Other cash flows from investing activities			(664)	155
Net cash used in investing activities			(258,841)	(415,990)
Cash flows from financing activities:
Repayments of finance leases and long-term debt			(100,147)	(38,148)
Proceeds from long-term debt			0	250,000
Borrowings on revolving lines of credit, net			53,000	167,000
Borrowings under accounts receivable securitization			22,000	0
Repayments of accounts receivable securitization			(96,600)	(80,000)
Proceeds from common stock issued			3,108	3,222
Dividends paid			(52,342)	(45,940)
Other cash flows from financing activities			(11,307)	(19,510)
Net cash (used in) provided by financing activities			(182,288)	236,624
Net (decrease) increase in cash, restricted cash, and equivalents			(130,429)	542,824
Cash, restricted cash, and equivalents at beginning of period			469,686	385,345	$ 385,345
Cash, restricted cash, and equivalents at end of period	$ 339,257	$ 928,169	339,257	928,169	$ 469,686
Cash paid during the period for:
Interest			86,931	45,851
Income taxes			7,695	16,870
Other Significant Noncash Transactions [Line Items]
Equipment acquired included in accounts payable			29,444	30,789
Right-of-use assets obtained in exchange for operating lease liabilities			25,247	30,564
Property and equipment obtained in exchange for finance lease liabilities			77,472	19,797
Financing provided to independent contractors for equipment sold
Other Significant Noncash Transactions [Line Items]
Other non-cash investing and financing activities			1,636	3,778
Transfers from property and equipment to assets held for sale [Member]
Other Significant Noncash Transactions [Line Items]
Other non-cash investing and financing activities			49,673	80,947
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