Summary of Significant Accounting Policies - Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Inventory, net
Raw materials	$ 116,840	$ 124,635
Work-in-progress	20,329	19,113
Finished goods	28,418	22,559
Total inventory	165,587	166,307
Inventory Valuation Reserves	$ 27,900	$ 28,900

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.

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

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of unprocessed items to be consumed in the manufacturing or production process.

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Amount of valuation reserve for inventory.

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Carrying amount, net of reserves and adjustments, as of the balance sheet date of merchandise or goods which are partially completed. This inventory is generally comprised of raw materials, labor and factory overhead costs, which require further materials, labor and overhead to be converted into finished goods, and which generally require the use of estimates to determine percentage complete and pricing.

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