Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Receivables, allowance for credit loss	$ 10,095	$ 15,057
Long-term receivables, allowance for credit loss	$ 5,503	$ 7,999
Preferred stock, par value (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 (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)	25,011,253	24,882,122
Common stock, shares outstanding (in shares)	17,177,950	16,452,174
Treasury stock, shares (in shares)	7,833,303	8,429,948