CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net income	$ 245,580	$ 261,478	$ 169,078
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	279,923	267,700	263,286
Deferred income taxes	42,553	29,488	(10,233)
Gain on disposal of property and equipment	(88,564)	(60,528)	(11,271)
Non-cash equity compensation	12,486	10,807	8,903
Insurance and claims accruals, net of current portion	7,726	5,582	3,420
Gain on investments in equity securities, net	(12,195)	(40,317)	0
Other	(13,295)	(3,105)	13,641
Changes in certain working capital items:
Accounts receivable, net	3,174	(101,007)	(18,258)
Other current assets	(18,333)	(27,903)	(7,390)
Accounts payable	(3,665)	14,742	(2,483)
Other current liabilities	(6,679)	(24,118)	37,216
Net cash provided by operating activities	448,711	332,819	445,909
Cash flows from investing activities:
Additions to property and equipment	(507,252)	(370,850)	(413,065)
Proceeds from sales of property and equipment	189,673	177,801	146,824
Net cash invested in acquisitions	(184,118)	(201,845)	0
Investment in equity securities	(20,250)	(10,000)	(5,000)
Decrease in notes receivable	7,614	7,593	7,966
Net cash used in investing activities	(514,333)	(397,301)	(263,275)
Cash flows from financing activities:
Repayments of short-term debt	(3,750)	(27,500)	(90,000)
Proceeds from issuance of short-term debt	0	5,000	40,000
Repayments of long-term debt	(100,000)	0	(50,000)
Proceeds from issuance of long-term debt	370,000	250,000	0
Dividends on common stock	(32,162)	(29,083)	(24,888)
Repurchases of common stock	(110,400)	(104,444)	(56,521)
Tax withholding related to net share settlements of restricted stock awards	(4,082)	(4,270)	(4,553)
Distribution to noncontrolling interest	(1,572)	(35)	0
Net cash provided by (used in) financing activities	118,034	89,668	(185,962)
Effect of exchange rate fluctuations on cash	632	(324)	(780)
Net increase (decrease) in cash and cash equivalents	53,044	24,862	(4,108)
Cash and cash equivalents, beginning of period	54,196	29,334	33,442
Cash and cash equivalents, end of period	107,240	54,196	29,334
Supplemental disclosures of cash flow information:
Interest paid	11,186	4,228	4,415
Income taxes paid	40,313	81,185	54,173
Supplemental schedule of non-cash investing and financing activities:
Notes receivable issued upon sale of property and equipment	5,577	5,953	3,441
Change in fair value of interest rate swaps	6,886	3,610	(5,238)
Property and equipment acquired included in accounts payable	5,937	7,124	12,250
Property and equipment disposed included in other receivables	110	0	30
Dividends accrued but not yet paid at end of period	8,220	7,895	6,114
Noncontrolling interest associated with acquisition	0	33,556	0
Contingent consideration associated with acquisition	$ 13,400	$ 2,500	$ 0