Condensed Consolidated Balance Sheet (Parentheticals) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for parts and supplies	$ 274	$ 274
Preferred stock, par value (in dollars per share)	$ 0.10	$ 0.10
Preferred stock, authorized	10,000	10,000
Preferred stock, issued	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	100,000	100,000
Common stock, outstanding	30,420	30,245