Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Receivables, allowance for credit loss	$ 4,959	$ 15,057
Long-term receivables, allowance for credit loss	$ 6,897	$ 7,999
Stockholders' deficit:
Preferred stock, par or stated value per share (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	40,000,000	40,000,000
Common stock, shares issued (in shares)	24,992,275	24,882,122
Common stock, shares outstanding (in shares)	17,163,946	16,452,174
Treasury stock, shares outstanding (in shares)	7,828,329	8,429,948