Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 124,587	$ 139,330
Marketable securities, at fair value	125,843	125,012
Accounts and notes receivable, less allowance for doubtful accounts of $57,485 and $59,906 as of June 30, 2021 and December 31, 2020, respectively	271,081	255,474
Inventories and supplies	28,008	31,586
Prepaid expenses and other assets	40,973	21,001
Total current assets	590,492	572,403
Property and equipment, net	26,922	26,561
Goodwill	61,659	51,084
Other intangible assets, less accumulated amortization of $25,573 and $23,466 as of June 30, 2021 and December 31, 2020, respectively	17,208	18,187
Notes receivable — long–term portion, less allowance for doubtful accounts of $6,875 and $7,895 as of June 30, 2021 and December 31, 2020, respectively	35,156	34,417
Deferred compensation funding, at fair value	50,434	46,825
Deferred income taxes	36,123	35,554
Total assets	817,994	785,031
Current liabilities:
Accounts payable	51,341	52,239
Accrued payroll and related taxes	58,348	70,614
Other accrued expenses	40,971	17,797
Income taxes payable	2,595	0
Accrued insurance claims	23,368	21,610
Total current liabilities	176,623	162,260
Accrued insurance claims — long-term portion	62,005	60,818
Deferred compensation liability	50,406	46,827
Accrued payroll and related taxes - noncurrent	23,302	23,302
Lease liability — long-term portion	11,651	11,363
Other long-term liabilities	5,703	0
Commitments and contingencies (Note 14)
STOCKHOLDERS’ EQUITY:
Common stock, $0.01 par value; 100,000 shares authorized; 75,969 and 75,798 shares issued, and 74,670 and 74,485 shares outstanding as of June 30, 2021 and December 31, 2020, respectively	760	758
Additional paid-in capital	289,138	282,206
Retained earnings	203,793	200,893
Accumulated other comprehensive income, net of taxes	4,995	5,563
Common stock in treasury, at cost, 1,299 and 1,313 shares as of June 30, 2021 and December 31, 2020, respectively	(10,382)	(8,959)
Total stockholders’ equity	488,304	480,461
Total liabilities and stockholders’ equity	$ 817,994	$ 785,031