Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Inventory [Line Items]
Raw materials	$ 90,695	$ 84,492
Work-in-process	42,812	43,140
Finished goods	39,534	40,321
At cost - FIFO basis:	173,041	167,953
LIFO cost less than FIFO cost	(14,728)	(15,067)
Net inventories	$ 158,313	$ 152,886

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

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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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Amount by which inventory stated at last-in first-out (LIFO) is less than (in excess of) inventory stated at other inventory cost methods.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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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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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