CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net income	$ 112,290	$ 245,580	$ 261,478
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	299,509	279,923	267,700
Deferred income taxes	8,153	42,553	29,488
Gain on disposal of property and equipment	(42,440)	(88,564)	(60,528)
Non-cash equity compensation	11,943	12,486	10,807
Insurance and claims accruals, net of current portion	(5,246)	7,726	5,582
Loss (gain) on investments in equity securities, net	278	(12,195)	(40,317)
Loss from equity method investment	1,046	0	0
Other	(7,612)	(13,295)	(3,105)
Changes in certain working capital items:
Accounts receivable, net	73,921	3,174	(101,007)
Other current assets	10,266	(18,333)	(27,903)
Accounts payable	3,288	(3,665)	14,742
Other current liabilities	8,970	(6,679)	(24,118)
Net cash provided by operating activities	474,366	448,711	332,819
Cash flows from investing activities:
Additions to property and equipment	(598,785)	(507,252)	(370,850)
Proceeds from sales of property and equipment	190,087	189,673	177,801
Net cash invested in acquisitions	(188)	(184,118)	(201,845)
Investment in equity securities, net	(2,931)	(20,250)	(10,000)
Payments to acquire equity method investment	(3,385)	0	0
Purchase of promissory note	(25,000)	0	0
Decrease in notes receivable	5,258	7,614	7,593
Net cash used in investing activities	(434,944)	(514,333)	(397,301)
Cash flows from financing activities:
Repayments of short-term debt	(50,000)	(3,750)	(27,500)
Proceeds from issuance of short-term debt	45,000	0	5,000
Repayments of long-term debt	(90,000)	(100,000)	0
Proceeds from issuance of long-term debt	50,000	370,000	250,000
Dividends on common stock	(34,208)	(32,162)	(29,083)
Repurchases of common stock	0	(110,400)	(104,444)
Tax withholding related to net share settlements of restricted stock awards	(6,359)	(4,082)	(4,270)
Distribution to noncontrolling interest	0	(1,572)	(35)
Other	(1,500)	0	0
Net cash provided by (used in) financing activities	(87,067)	118,034	89,668
Effect of exchange rate fluctuations on cash	2,128	632	(324)
Net increase (decrease) in cash and cash equivalents	(45,517)	53,044	24,862
Cash and cash equivalents, beginning of period	107,240	54,196	29,334
Cash and cash equivalents, end of period	61,723	107,240	54,196
Supplemental disclosures of cash flow information:
Interest paid	27,212	11,186	4,228
Income taxes paid	17,892	40,313	81,185
Supplemental schedule of non-cash investing and financing activities:
Notes receivable issued upon sale of property and equipment	3,145	5,577	5,953
Change in fair value of interest rate swaps	(4,512)	6,886	3,610
Property and equipment acquired included in accounts payable	14,239	5,937	7,124
Property and equipment disposed included in other receivables	0	110	0
Dividends accrued but not yet paid at end of period	8,882	8,220	7,895
Noncontrolling interest associated with acquisition	0	0	33,556
Contingent consideration associated with acquisition	$ (800)	$ 13,400	$ 2,500