CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities:
Net income	$ 89,058,000	$ 184,569,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	223,797,000	206,097,000
Deferred income taxes	23,775,000	10,262,000
Gain on disposal of property and equipment	(39,346,000)	(62,659,000)
Non-cash equity compensation	8,671,000	9,120,000
Insurance and claims accruals, net of current portion	(6,866,000)	1,469,000
Loss (gain) on investments in equity securities, net	36,000	(14,403,000)
Loss from equity method investment	954,000	0
Other	(4,741,000)	(5,056,000)
Changes in certain working capital items:
Accounts receivable, net	69,079,000	(32,258,000)
Other current assets	(12,135,000)	3,922,000
Accounts payable	5,844,000	21,061,000
Other current liabilities	(2,107,000)	10,592,000
Net cash provided by operating activities	356,019,000	332,716,000
Cash flows from investing activities:
Additions to property and equipment	(530,085,000)	(379,902,000)
Proceeds from sales of property and equipment	155,924,000	125,830,000
Net cash invested in acquisition	(188,000)	705,000
Investment in equity securities, net	(2,865,000)	(20,250,000)
Payment to acquire equity method investment	(2,645,000)	0
Issuance of notes receivable	(25,000,000)	0
Decrease in notes receivable	2,809,000	4,870,000
Net cash used in investing activities	(402,050,000)	(268,747,000)
Cash flows from financing activities:
Repayments of short-term debt	(33,750,000)	(3,750,000)
Proceeds from issuance of short-term debt	30,000,000	0
Repayments of long-term debt	(50,000,000)	(100,000,000)
Proceeds from issuance of long-term debt	50,000,000	250,000,000
Change in checks issued in excess of cash balances	14,659,000	0
Dividends on common stock	(25,333,000)	(23,946,000)
Repurchases of common stock	0	(110,400,000)
Tax withholding related to net share settlements of restricted stock awards	(5,554,000)	(3,704,000)
Other cash flows from financing activities	0	(750,000)
Net cash provided by (used in) financing activities	(19,978,000)	7,450,000
Effect of exchange rate fluctuations on cash	1,523,000	68,000
Net increase (decrease) in cash and cash equivalents	(64,486,000)	71,487,000
Cash and cash equivalents, beginning of period	107,240,000	54,196,000
Cash and cash equivalents, end of period	42,754,000	125,683,000
Supplemental disclosures of cash flow information:
Interest paid	25,299,000	5,664,000
Income taxes paid	17,140,000	38,797,000
Supplemental schedule of non-cash investing and financing activities:
Notes receivable issued upon sale of property and equipment	1,968,000	3,771,000
Change in fair value of interest rate swaps	(1,768,000)	6,772,000
Property and equipment acquired included in accounts payable	4,701,000	7,143,000
Property and equipment disposed included in other receivables	0	190,000
Dividends accrued but not yet paid at end of period	8,875,000	8,216,000
Contingent consideration associated with acquisitions	$ (800,000)	$ 0