Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income	$ 25,886	$ 44,568
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	4,836	4,239
Bad debt provision	39,387	2,100
Stock-based compensation expense, net of tax benefit from equity compensation plans	2,026	315
Amortization of premium on marketable securities	653	569
Unrealized gain on deferred compensation fund investments	(1,259)	(2,304)
Changes in operating assets and liabilities:
Accounts and notes receivable	(26,242)	(69,187)
Inventories and supplies	969	(238)
Prepaid expenses and other assets	(2,458)	(6,089)
Deferred compensation funding	(531)	98
Accounts payable and other accrued expenses	(6,628)	5,550
Accrued payroll, accrued and withheld payroll taxes	(1,690)	1,572
Income taxes payable	(15,955)	7,343
Accrued insurance claims	6,461	2,399
Deferred compensation liability	1,940	2,504
Net cash provided by (used in) operating activities	27,395	(6,561)
Cash flows from investing activities:
Disposals of fixed assets	222	169
Additions to property and equipment	(2,572)	(2,674)
Purchases of marketable securities	(9,453)	(15,939)
Sales of marketable securities	5,775	14,681
Cash paid for acquisitions	0	(2,584)
Net cash used in investing activities	(6,028)	(6,347)
Cash flows from financing activities:
Dividends paid	(28,398)	(27,374)
Reissuance of treasury stock pursuant to Dividend Reinvestment Plan	46	48
Proceeds from the exercise of stock options	5,460	7,257
Net proceeds from short-term borrowings	5,123	16,182
Net cash used in financing activities	(17,769)	(3,887)
Net change in cash and cash equivalents	3,598	(16,795)
Cash and cash equivalents at beginning of the period	9,557	23,853
Cash and cash equivalents at end of the period	$ 13,155	$ 7,058