Amount of cost incurred on construction contract for unapproved change order, claim, or similar item subject to uncertainty.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 910
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6471471&loc=d3e48698-109348

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

Revenue From Customers - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Costs and Estimated Earnings in Excess of Billings
Disaggregation of Revenue [Line Items]
Contracts receivable unpaid project contract price	$ 7,900		$ 7,900		$ 3,000
Operating income (Loss)
Disaggregation of Revenue [Line Items]
Estimated construction gain (loss) before tax	$ 2,700	$ 500	$ 5,000	$ 3,700