Note 3 - Contracts in Progress - Changes in Estimates (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Increase in revenue from net changes in transaction prices	$ 254,000	$ 148,000
Decrease in revenue from net changes in input cost estimates	(268,000)	(126,000)
Net (decrease) increase in revenue from net changes in estimates	$ (14,000)	$ 22,000
Number of projects	10	2
Net change in estimate as a percentage of aggregate revenue for associated projects	(0.08%)	0.06%