Consolidated Statements of Cash Flow - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating activities
Net income	$ 72,140	$ 61,290	$ 65,699
Adjustments to reconcile net income to net cash provided by operating activities net of assets/liabilities acquired:
Depreciation	53,571	51,969	52,927
Amortization	5,072	3,228	3,044
Gain on sale of assets	(7,169)	(8,586)	(5,653)
Deferred income taxes	1,175	(2,070)	(1,652)
Other	2,790	5,593	4,091
Changes in operating assets and liabilities, net of assets acquired:
Accounts receivable	(38,086)	(33,714)	(24,853)
Accounts payable and accrued expenses	7,720	4,812	(26,349)
Increase (Decrease) in Self Insurance Reserve	284	8,185	16,685
Increase (Decrease) in Inventories	17,664	0	0
Other assets and liabilities, net	(8,383)	(12,809)	(7,970)
Adjustments to reconcile net income to net cash provided by operating activities	(690)	16,608	10,270
Net cash provided by operating activities	71,450	77,898	75,969
Capital expenditures:
Equipment	(65,286)	(68,802)	(50,929)
Land and buildings	(22,036)	(20,438)	(16,599)
Purchases of businesses, net of cash acquired and debt incurred	(21,497)	(21,826)	(11,725)
Proceeds from sales of property and equipment	12,231	10,557	6,955
Purchases of marketable securities	(47,199)	(46,833)	(14,888)
Proceeds from sale of marketable securities	43,912	15,826	8
Net cash used in investing activities	(99,875)	(131,516)	(87,178)
Financing activities
Revolving credit facility borrowings	788,165	662,531	420,443
Revolving credit facility payments	796,982	558,930	374,324
Proceeds from notes payable	164,107	71,152	235,083
Payments of notes payable	(93,327)	(78,903)	(235,087)
Payments of financing leases	(3,973)	(2,987)	(3,348)
Purchases of common shares for treasury	(78,076)	(75,694)	(50,946)
Sales of common shares from treasury	41,172	35,588	25,520
Cash received on common-share subscriptions	3,682	3,610	0
Dividends	(3,850)	(3,540)	(2,898)
Net cash provided by financing activities	20,918	52,827	14,443
Effect of exchange rate changes on cash	51	(143)	25
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	(7,456)	(934)	3,259
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents		18,526	19,460
Cash, beginning of year	18,526	19,460
Cash, end of year	$ 11,070	$ 18,526	$ 19,460