Construction Contracts (Summary of Costs in Excess of Billings and Billings in Excess of Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Change In Contract With Customer, Asset [Roll Forward]
Beginning balance	$ 1,358	$ 245
Transferred to receivables	(2,557)	(245)
Construction contract costs and estimated earnings not billed during the period	249	352
Changes due to cumulative catch-up adjustment arising from changes in the estimate of the stage of completion	1,199	1,006
Ending balance	249	1,358
Change In Contract With Customer, Liability [Roll Forward]
Beginning balance	3,037	3,591
Revenue recognized that was included in the balance at the beginning of the period	(3,037)	(3,591)
Increases due to new billings, excluding amounts recognized as revenue during the period	6,283	4,243
Changes due to cumulative catch-up adjustment arising from changes in the estimate of the stage of completion	(977)	(1,206)
Ending balance	$ 5,306	$ 3,037