CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
CURRENT ASSETS:
Accounts receivable, allowance	$ 25,987	$ 26,837
PROPERTY, EQUIPMENT AND FACILITIES - accumulated depreciation and amortization	148,132	153,335
OTHER ASSETS:
Noncurrent receivables, allowance	$ 5,591	$ 5,084
STOCKHOLDERS' EQUITY:
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	26,924,020	27,000,687
Common stock, shares outstanding (in shares)	26,924,020	27,000,687
Treasury stock, shares (in shares)	0	5,910,541
Series A Convertible Preferred Stock [Member]
SERIES A CONVERTIBLE PREFERRED STOCK
Preferred stock, par value (in dollars per share)	$ 0	$ 0
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	12,700	12,700
Preferred stock, shares outstanding (in shares)	12,700	12,700