Contracts in Progress (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Contractors [Abstract]
Contract revenues	$ 159,767	$ 137,420	$ 296,610	$ 276,177
Costs incurred on uncompleted contracts	739,863		739,863			$ 668,848
Estimated earnings	140,773		140,773			120,751
Costs incurred and estimated earnings on uncompleted contracts	880,636		880,636			789,599
Less: Billings to date	(852,418)		(852,418)			(777,516)
Costs and estimated earnings in excess of billings on uncompleted contracts, net	28,218		28,218			12,083
Costs and estimated earnings in excess of billings on uncompleted contracts	53,287		53,287		$ 47,389	46,006
Billings in excess of costs and estimated earnings on uncompleted contracts	(25,069)		(25,069)		$ (35,668)	$ (33,923)
Contract with customer, liability, revenue recognized	$ 12,900		$ 19,600

Costs in Excess of Billings on Uncompleted Contracts, Net

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Inventory for Long-term Contracts or Programs, Costs Incurred on Uncompleted Contracts

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Inventory for Long-term Contracts or Programs, Estimated Earnings on Uncompleted Contracts

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Amounts due for billed services rendered or to be rendered, actions taken or to be taken, or a promise to refrain from taking certain actions in accordance with the terms of a legally binding agreement between the Company and, at a minimum, one other party. An example would be amounts billed to customers under contracts or programs but not paid as of the balance sheet date.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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Liability attributable to (i) billings in excess of costs under the percentage of completion contract accounting method representing the difference between contractually invoiced amounts (billings) and revenue recognized based, for example, on costs incurred to estimated total costs at period end or (ii) contractually invoiced amounts (billings) in excess of costs incurred and accumulated under the completed contract accounting method that are expected to be realized within one year or one operating cycle, whichever is longer, from the reporting date.

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Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

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Amount of revenue earned from products sold or services provided under the terms of a contract, including, but not limited to, government contracts and construction contracts, classified as other.

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Amount of receivable reflecting the cost incurred on uncompleted contracts in excess of related billings which is expected to be collected within one year or the normal operating cycle, if longer.

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Amount before valuation and LIFO reserves, and progress payments, of inventory associated with long-term contracts, expected to be sold, or consumed within one year or operating cycle, if longer.

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