Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income	$ 70,935	$ 45,686
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	10,752	10,397
Bad debt provision	6,756	22,980
Deferred income tax (benefit) expense	(8,247)	119
Share-based compensation expense	5,917	5,468
Amortization of premium on marketable securities	1,409	1,019
Unrealized gain on deferred compensation fund investments	(4,210)	(5,048)
Changes in operating assets and liabilities:
Accounts and notes receivable	22,440	(24,636)
Inventories and supplies	3,825	2,394
Prepaid expenses and other assets	(3,588)	641
Deferred compensation funding	488	(223)
Accounts payable and other accrued expenses	(9,104)	(9,420)
Accrued payroll, accrued and withheld payroll taxes	14,356	21,197
Income taxes payable	17,420	(4,074)
Accrued insurance claims	8,450	8,001
Deferred compensation liability	3,950	5,721
Net cash provided by operating activities	141,549	80,222
Cash flows from investing activities:
Disposals of fixed assets	475	127
Additions to property and equipment	(3,074)	(3,384)
Purchases of marketable securities	(8,242)	(18,627)
Sales of marketable securities	5,979	17,628
Net cash used in investing activities	(4,862)	(4,256)
Cash flows from financing activities:
Dividends paid	(45,383)	(44,065)
Reissuance of treasury stock pursuant to Dividend Reinvestment Plan	69	67
Proceeds from the exercise of stock options	1,893	3,166
Repayments of short-term borrowings	(10,000)	(20,000)
Payments of statutory withholding on net issuance of restricted stock units	(675)	(587)
Net cash used in financing activities	(54,096)	(61,419)
Net change in cash and cash equivalents	82,591	14,547
Cash and cash equivalents at beginning of the period	27,329	26,025
Cash and cash equivalents at end of the period	$ 109,920	$ 40,572