Inventories (Detail) - USD ($) $ in Thousands	Jun. 29, 2018	Jan. 01, 2018	Dec. 31, 2017
Principally average cost:
Raw materials and supplies	$ 40,550		$ 42,958
Work in process	176,216		187,719
Finished goods	41,017		34,418
Subtotal	257,783		265,095
Less: LIFO reserve balance	48,579		44,743
Inventories	$ 209,204	$ 218,293	$ 220,352

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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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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