Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income	$ 108,522	$ 118,448
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	199,487	184,816
Deferred income taxes	(2,358)	8,413
Gain on disposal of property and equipment	(7,293)	(14,530)
Non-cash equity compensation	6,003	6,346
Insurance and claims accruals, net of current portion	6,579	15,840
Other	21,771	(4,527)
Changes in certain working capital items:
Accounts receivable, net	(15,051)	14,552
Other current assets	(1,335)	5,667
Accounts payable	6,477	(532)
Other current liabilities	23,594	(2,308)
Net cash provided by operating activities	346,396	332,185
Cash flows from investing activities:
Additions to property and equipment	(294,448)	(375,202)
Proceeds from sales of property and equipment	107,185	103,543
Decrease in notes receivable	6,277	9,247
Net cash used in investing activities	(180,986)	(262,412)
Cash flows from financing activities:
Repayments of short-term debt	(75,000)	0
Repayments of long-term debt	(50,000)	(50,000)
Proceeds from issuance of long-term debt	0	275,000
Change in net checks issued in excess of cash balances	0	8,902
Dividends on common stock	(18,669)	(279,962)
Repurchases of common stock	(8,798)	(42,301)
Tax withholding related to net share settlements of restricted stock awards	(3,941)	(1,191)
Stock options exercised	0	171
Net cash used in financing activities	(156,408)	(89,381)
Effect of exchange rate fluctuations on cash	(1,968)	32
Net increase (decrease) in cash, cash equivalents and restricted cash	7,034	(19,576)
Cash, cash equivalents and restricted cash, beginning of period	33,442	33,930
Cash, cash equivalents and restricted cash, end of period	40,476	14,354
Supplemental disclosures of cash flow information:
Interest paid	3,882	4,361
Income taxes paid	36,880	41,038
Supplemental schedule of non-cash investing and financing activities:
Notes receivable issued upon sale of property and equipment	2,283	5,542
Change in fair value of interest rate swaps	(5,819)	(1,651)
Property and equipment acquired included in accounts payable	24,068	8,847
Property and equipment disposed included in other receivables	5,183	1,486
Dividends accrued but not yet paid at end of period	$ 6,219	$ 6,229