XML 41 R27.htm IDEA: XBRL DOCUMENT

Note 4 - Revenue From Contracts With Customers - Changes in Estimates (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Increase in revenue from net changes in transaction prices	$ 0	$ 34,000	$ 9,000	$ 75,000
(Decrease) increase in revenue from net changes in input cost estimates	(61,000)	(479,000)	(240,000)	(570,000)
Net (decrease) increase in revenue from net Changes in estimates	$ (61,000)	$ (445,000)	$ (231,000)	$ (495,000)
Number of projects	26	15	26	10
Net change in estimate as a percentage of aggregate revenue for associated projects	(0.90%)	(9.20%)	(0.50%)	(8.80%)