Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net income	$ 24,653	$ 20,190
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3,607	3,556
Bad debt provision	3,415	2,060
Share-based compensation expense	2,271	1,973
Amortization of premium on marketable securities	536	450
Unrealized (gain) loss on deferred compensation fund investments	(1,146)	5,761
Loss on sale of assets	268	0
Changes in operating assets and liabilities:
Accounts and notes receivable	1,903	(9,645)
Inventories and supplies	2,416	(421)
Prepaid expenses and other assets	(19,814)	(4,574)
Deferred compensation funding	990	1,478
Accounts payable and other accrued expenses	6,064	(379)
Accrued payroll, accrued and withheld payroll taxes	(30,747)	(4,626)
Income taxes payable	7,908	2,480
Accrued insurance claims	622	1,379
Deferred compensation liability	556	(6,994)
Net cash provided by operating activities	3,502	12,688
Cash flows from investing activities:
Disposals of fixed assets	54	129
Additions to property and equipment	(850)	(788)
Purchases of marketable securities	(7,902)	(2,670)
Sales of marketable securities	4,995	1,757
Net cash used in investing activities	(3,703)	(1,572)
Cash flows from financing activities:
Dividends paid	(15,472)	(15,033)
Reissuance of treasury stock pursuant to Dividend Reinvestment Plan	23	23
Proceeds from the exercise of stock options	1,475	1,724
Proceeds from short-term borrowings	0	40,000
Payments of statutory withholding on net issuance of restricted stock units	(1,501)	(661)
Net cash (used in) provided by financing activities	(15,475)	26,053
Net change in cash and cash equivalents	(15,676)	37,169
Cash and cash equivalents at beginning of the period	139,330	27,329
Cash and cash equivalents at end of the period	$ 123,654	$ 64,498