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	$ 38,386	$ 34,243	$ 48,543
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	14,344	15,316	14,667
Bad debt provision	35,604	31,969	10,483
Deferred income tax (benefit) expense	(4,820)	4,907	4,083
Share-based compensation expense	8,985	9,214	8,827
Amortization of premium on marketable securities	2,144	2,219	2,275
Unrealized (gain) loss on deferred compensation fund investments	(6,645)	9,422	(6,397)
Changes in fair value of other long-term liabilities	(1,154)	(2,353)	0
Net loss on disposals of property and equipment	818	1,138	1,469
Changes in operating assets and liabilities:
Accounts and notes receivable	(74,559)	(78,707)	(37,185)
Inventories and supplies	2,685	4,851	5,599
Prepaid expenses and other assets	12,750	9,935	(12,250)
Deferred compensation funding, net	(674)	3,913	6,661
Accounts payable and other accrued expenses	7,430	(13,748)	10,244
Accrued payroll, accrued and withheld payroll taxes	4,186	(23,859)	(25,878)
Income taxes receivable and payable	572	2,184	(8,420)
Accrued insurance claims	(4,329)	(687)	6,966
Deferred compensation liability	7,775	(18,124)	7,421
Net cash provided by (used in) operating activities	43,498	(8,167)	37,108
Cash flows (used in) from investing activities:
Disposals of property and equipment	121	393	211
Additions to property and equipment	(5,406)	(5,210)	(5,687)
Purchases of marketable securities	0	(2,875)	(20,335)
Sales of marketable securities	1,992	10,386	26,697
Cash paid for acquisitions	0	(114)	(23,876)
Net cash (used in) provided by investing activities	(3,293)	2,580	(22,990)
Cash flows used in financing activities:
Dividends paid	0	(63,373)	(62,226)
Reissuance of treasury stock pursuant to Dividend Reinvestment Plan	0	106	92
Proceeds from the exercise of stock options	0	410	2,425
Purchases of treasury stock	(11,283)	0	(21,535)
Short-term borrowings, net of repayments	0	25,000	0
Payments of statutory withholding on net issuance of restricted stock units	(871)	(1,071)	(1,410)
Net cash used in financing activities	(12,154)	(38,928)	(82,654)
Net change in cash and cash equivalents	28,051	(44,515)	(68,536)
Cash and cash equivalents at beginning of the period	26,279	70,794	139,330
Cash and cash equivalents at end of the period	54,330	26,279	70,794
Supplementary cash flow information:
Cash paid for interest	7,809	2,822	1,385
Cash paid for income taxes	5,585	3,309	21,233
Accrued variable consideration for acquisition of businesses	$ 0	$ 0	$ 10,456