Costs and Estimated Earnings on Uncompleted Contracts (Costs and Estimated Earnings on Uncompleted Contracts Accompanying Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Costs and Estimated Earnings on Uncompleted Contracts [Abstract]
Costs and estimated earnings in excess of billings on uncompleted contracts	$ 27,109	$ 26,313
Billings in excess of costs and estimated earnings on uncompleted contracts (included in Other current liabilities)	(1,040)	(1,421)
Costs and estimated earnings on uncompleted contracts	$ 26,069	$ 24,892