Costs and Estimated Earnings on Uncompleted Contracts (Summary of Costs and Estimated Earnings on Uncompleted Contracts) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Costs and Estimated Earnings on Uncompleted Contracts [Abstract]
Costs incurred on uncompleted contracts	$ 62,753	$ 54,949
Estimated earnings	25,149	21,778
Billings to date	(51,333)	(43,725)
Costs and estimated earnings on uncompleted contracts	$ 36,569	$ 33,002

Amount, after accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=68051541&loc=SL49131252-203054

Name:	us-gaap_CapitalizedContractCostNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant