Contract Assets and Liabilities - Activity (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Costs incurred on uncompleted contracts	$ 91,513	$ 65,343
Estimated earnings	12,827	9,618
Total costs and estimated earnings	104,340	74,961
Less billings to date	(102,862)	(55,782)
Costs and estimated earnings in excess of billings	$ 1,478	$ 19,179