Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Revenue, Major Customer [Line Items]
Costs and estimated earnings in excess of billings on uncompleted contracts	$ 31,433		$ 41,389
Billings in excess of costs and estimated earnings on uncompleted contracts	53,412		48,781
Deferred income tax liability	213		205
Retained earnings	(34,497)		(37,220)
Contract revenues	166,620	$ 143,105
Costs of contract revenues	146,862	134,023
Gross profit	19,758	9,082
Income tax (benefit) expense	377	593
Net (loss) income	$ 2,723	$ (7,924)
Basic (loss) income per share (in dollars per share)	$ 0.09	$ (0.27)
Diluted (loss) income per share (in dollars per share)	$ 0.09	$ (0.27)
Costs And Estimated Earnings In Excess Of Billings On Uncompleted Contracts
Revenue, Major Customer [Line Items]
Costs and estimated earnings in excess of billings on uncompleted contracts	$ 200		$ 100