Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net income	$ 34,218	$ 43,291
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	7,302	7,146
Bad debt provision	6,709	5,921
Deferred income tax benefit	0	(3,923)
Share-based compensation expense	4,569	3,925
Amortization of premium on marketable securities	1,138	950
Unrealized gain on deferred compensation fund investments	(4,053)	(961)
Loss on sale of assets	597	0
Changes in operating assets and liabilities:
Accounts and notes receivable	(23,054)	2,635
Inventories and supplies	3,578	2,840
Prepaid expenses and other assets	(19,972)	(3,931)
Deferred compensation funding	444	990
Accounts payable and other accrued expenses	17,827	(964)
Accrued payroll, accrued and withheld payroll taxes	(10,088)	16,104
Income taxes payable	2,595	12,847
Accrued insurance claims	2,945	5,396
Deferred compensation liability	4,087	117
Net cash provided by operating activities	28,842	92,383
Cash flows from investing activities:
Disposals of fixed assets	84	307
Additions to property and equipment	(2,093)	(1,835)
Purchases of marketable securities	(15,138)	(6,939)
Sales of marketable securities	12,031	5,779
Cash paid for acquisition	(6,000)	0
Net cash used in investing activities	(11,116)	(2,688)
Cash flows from financing activities:
Dividends paid	(31,034)	(30,161)
Reissuance of treasury stock pursuant to Dividend Reinvestment Plan	46	45
Proceeds from the exercise of stock options	1,855	1,862
Purchases of treasury stock	(1,835)	0
Repayments of short-term borrowings	0	(10,000)
Payments of statutory withholding on net issuance of restricted stock units	(1,501)	(661)
Net cash used in financing activities	(32,469)	(38,915)
Net change in cash and cash equivalents	(14,743)	50,780
Cash and cash equivalents at beginning of the period	139,330	27,329
Cash and cash equivalents at end of the period	124,587	78,109
Supplemental disclosure of non-cash investing activities
Accrued variable consideration from acquisition of a business	$ 5,703	$ 0