Inventories - Summary (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Inventory, Net [Abstract]
Raw materials	$ 34,023	$ 28,672
Work in process	16,013	29,427
Finished goods	24,227	23,901
Gross inventory total	74,263	82,000
Less: Progress billings	0	(1,661)
Total inventories	$ 74,263	$ 80,339

Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of merchandise or goods held by the company that are readily available for sale.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(6)(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 5.BB)
-URI http://asc.fasb.org/extlink&oid=27011343&loc=d3e100047-122729

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- Definition

Gross amount, as of the balance sheet date, of merchandise, goods, commodities, or supplies held for future sale or to be used in manufacturing, servicing or production process.

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- Definition

Amount, after deduction of valuation reserves, other allowances, and customer advances received on long-term contracts or programs, of inventory expected to be converted to cash, sold or exchanged within the normal operating cycle.

+ References

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- Definition

Amount before valuation and LIFO reserves of raw materials expected to be sold, or consumed within one year or operating cycle, if longer.

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Amount before valuation and LIFO reserves of merchandise or goods in the production process expected to be completed within one year or operating cycle, if longer.

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- Definition

Amount of advances received from customers under long-term contracts which have been offset against inventories accounts at the balance sheet date.

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