Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income	$ 27,342	$ 25,886
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	6,997	4,836
Bad debt provision	21,465	39,387
Stock-based compensation expense	3,659	3,095
Deferred income tax benefit	(18)	0
Amortization of premium on marketable securities	712	653
Unrealized gain on deferred compensation fund investments	(5,041)	(1,259)
Changes in operating assets and liabilities:
Accounts and notes receivable	(25,305)	(26,242)
Inventories and supplies	1,305	969
Prepaid expenses and other assets	(2,847)	(2,458)
Deferred compensation funding	89	(531)
Accounts payable and other accrued expenses	(8,824)	(6,628)
Accrued payroll, accrued and withheld payroll taxes	(2,678)	(1,690)
Income taxes payable	(7,140)	(17,024)
Accrued insurance claims	5,423	6,461
Deferred compensation liability	5,200	1,940
Net cash provided by operating activities	20,339	27,395
Cash flows from investing activities:
Disposals of fixed assets	87	222
Additions to property and equipment	(2,496)	(2,572)
Purchases of marketable securities	(8,234)	(9,453)
Sales of marketable securities	7,145	5,775
Net cash used in investing activities	(3,498)	(6,028)
Cash flows from financing activities:
Dividends paid	(29,276)	(28,398)
Reissuance of treasury stock pursuant to Dividend Reinvestment Plan	46	46
Proceeds from the exercise of stock options	3,099	5,755
Net repayments from short-term borrowings	0	5,123
Payments of statutory withholding on net issuance of restricted stock units	(579)	(295)
Net cash used in financing activities	(26,710)	(17,769)
Net change in cash and cash equivalents	(9,869)	3,598
Cash and cash equivalents at beginning of the period	26,025	9,557
Cash and cash equivalents at end of the period	$ 16,156	$ 13,155