Inventories (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Apr. 30, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 41,728	$ 18,230
Work-in-process	44,905	18,704
Finished goods	34,111	19,372
Total FIFO inventories	120,744	56,306
Reserve to adjust inventories to LIFO value	(15,943)	(13,447)
Total inventory	104,801	$ 42,859
Carried under FIFO	56,600
Carried under LIFO	$ 48,200

The amount of FIFO (first in first out) inventory present at the reporting date when inventory is also valued using different valuation methods.

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

+ References

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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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The amount of LIFO (last in first out) inventory present at the reporting date when inventory is also valued using different valuation methods.

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