Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income	$ 45,686	$ 51,972
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	10,397	7,022
Bad debt provision	22,980	42,387
Stock-based compensation expense	5,468	4,606
Deferred income tax benefit	119	0
Amortization of premium on marketable securities	1,019	1,007
Unrealized gain on deferred compensation fund investments	(5,048)	(3,071)
Changes in operating assets and liabilities:
Accounts and notes receivable	(24,636)	(49,873)
Inventories and supplies	2,394	798
Prepaid expenses and other assets	641	725
Deferred compensation funding	(223)	(1,141)
Accounts payable and other accrued expenses	(9,420)	55
Accrued payroll, accrued and withheld payroll taxes	21,197	23,202
Income taxes payable	(4,074)	(15,713)
Accrued insurance claims	8,001	8,249
Deferred compensation liability	5,721	4,284
Net cash provided by operating activities	80,222	74,509
Cash flows from investing activities:
Disposals of fixed assets	127	481
Additions to property and equipment	(3,384)	(3,739)
Purchases of marketable securities	(18,627)	(13,069)
Sales of marketable securities	17,628	8,706
Net cash used in investing activities	(4,256)	(7,621)
Cash flows from financing activities:
Dividends paid	(44,065)	(42,748)
Reissuance of treasury stock pursuant to Dividend Reinvestment Plan	67	68
Proceeds from the exercise of stock options	3,166	7,167
Net repayments from short-term borrowings	(20,000)	(25,423)
Payments of statutory withholding on net issuance of restricted stock units	(587)	(312)
Net cash used in financing activities	(61,419)	(61,248)
Net change in cash and cash equivalents	14,547	5,640
Cash and cash equivalents at beginning of the period	26,025	9,557
Cash and cash equivalents at end of the period	$ 40,572	$ 15,197