Investments (Details) - USD ($)	3 Months Ended	6 Months Ended
Nov. 30, 2020	Nov. 30, 2019	Nov. 30, 2020	Nov. 30, 2019	May 31, 2020
Investments, Debt and Equity Securities [Abstract]
Investments	$ 252,454,000		$ 252,454,000		$ 214,847,000
Cash surrender value of insurance policies	227,000,000.0		227,000,000.0		192,700,000
Equity method investments	22,300,000		22,300,000		19,000,000.0
Cost method investments	3,200,000		3,200,000		$ 3,100,000
Losses due to impairment	$ 0	$ 0	$ 0	$ 0

Carrying amount as of the balance sheet date of amounts which could be received based on the terms of the insurance contract upon surrendering life policies owned by the entity.

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- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Cost of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Excludes equity method investment and investment in equity security without readily determinable fair value.

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No definition available.

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The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-Topic 320
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Sum of the carrying amounts as of the balance sheet date of all investments.

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