Organization, Business and Basis of Presentation (Details) $ / shares in Units, $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020 USD ($) $ / shares	Mar. 31, 2020	Sep. 30, 2019 USD ($) $ / shares	Sep. 30, 2020 USD ($) segment $ / shares	Sep. 30, 2019 USD ($) $ / shares	Jan. 01, 2020 USD ($)	Dec. 31, 2019 USD ($)
Organization Consolidation and Presentation of Financial Statements [Line Items]
Number of business segments (segment) | segment				2
Foreign currency gains				$ 0	$ 100
Revenue recognized, related to change orders and claims included as contract price adjustments				19,100	31,100
Increase (decrease) in operating income	$ 24,929		$ 17,262	60,679	36,298
Increase (decrease) in net income	$ 17,292		$ 10,355	$ 40,609	$ 24,915
Increase (decrease) in diluted earnings per common share (in dollars per share) | $ / shares	$ 1.02		$ 0.62	$ 2.42	$ 1.49
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201613Member		us-gaap:AccountingStandardsUpdate201613Member
Decrease in retained earnings	$ 252,375			$ 252,375			$ 212,219
Total allowance for doubtful accounts	$ 502			$ 502		$ 400	147
Cumulative Effect Adjustment
Organization Consolidation and Presentation of Financial Statements [Line Items]
Decrease in retained earnings							$ (300)
Contracts Accounted for under Percentage of Completion
Organization Consolidation and Presentation of Financial Statements [Line Items]
Increase (decrease) in consolidated gross margin	(0.30%)		0.20%	(0.40%)	(0.50%)
Increase (decrease) in operating income	$ (1,900)		$ 900	$ (7,600)	$ (7,800)
Increase (decrease) in net income	$ (1,500)		$ 800	$ (5,500)	$ (3,300)
Increase (decrease) in diluted earnings per common share (in dollars per share) | $ / shares	$ (0.09)		$ 0.05	$ (0.33)	$ (0.20)