Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income	$ 20,190	$ 9,156
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3,556	3,489
Bad debt provision	2,060	18,470
Share-based compensation expense	1,973	1,838
Amortization of premium on marketable securities	450	382
Unrealized loss (gain) on deferred compensation fund investments	5,761	(3,445)
Changes in operating assets and liabilities:
Accounts and notes receivable	(9,645)	(25,986)
Inventories and supplies	(421)	300
Prepaid expenses and other assets	(4,574)	(323)
Deferred compensation funding	1,478	744
Accounts payable and other accrued expenses	(379)	(5,322)
Accrued payroll, accrued and withheld payroll taxes	(4,626)	18,465
Income taxes payable	2,480	(5,730)
Accrued insurance claims	1,379	2,622
Deferred compensation liability	(6,994)	2,917
Net cash provided by operating activities	12,688	17,577
Cash flows from investing activities:
Disposals of fixed assets	129	64
Additions to property and equipment	(788)	(1,336)
Purchases of marketable securities	(2,670)	(4,277)
Sales of marketable securities	1,757	3,539
Net cash used in investing activities	(1,572)	(2,010)
Cash flows from financing activities:
Dividends paid	(15,033)	(14,588)
Reissuance of treasury stock pursuant to Dividend Reinvestment Plan	23	24
Proceeds from the exercise of stock options	1,724	1,913
Proceeds from short-term borrowings	40,000	0
Payments of statutory withholding on net issuance of restricted stock units	(661)	(579)
Net cash provided by (used in) financing activities	26,053	(13,230)
Net change in cash and cash equivalents	37,169	2,337
Cash and cash equivalents at beginning of the period	27,329	26,025
Cash and cash equivalents at end of the period	$ 64,498	$ 28,362