Costs and Estimated Earnings on Uncompleted Contracts - Balance Sheet Classification (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Revenue Recognition and Deferred Revenue [Abstract]
Costs and estimated earnings in excess of billings	$ 90,375	$ 86,710
Billings in excess of costs and estimated earnings	(160)	(1,352)
Costs and estimated earnings in excess of billings	90,215	85,358
Long term contracts, loss accrual	$ 425	$ 677

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Balance Type:	credit
Period Type:	instant