Revenue Recognition - Schedule of Net Under (Over) Billings (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Costs and estimated earnings in excess of billings on uncompleted contracts (contract assets)	$ 28,370	$ 24,334
Billings in excess of costs and estimated earnings on uncompleted contracts (contract liabilities)	(4,741)	(4,718)
Net under billings	$ 23,629	$ 19,616