Investments (Details) - USD ($)	3 Months Ended	9 Months Ended
Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019	May 31, 2019
Investments, Debt and Equity Securities [Abstract]
Investments	$ 212,798,000		$ 212,798,000		$ 192,346,000
Cash surrender value of insurance policies	190,200,000		190,200,000		170,500,000
Equity method investments	19,400,000		19,400,000		18,600,000
Cost method investments	3,200,000		3,200,000		$ 3,200,000
Losses due to impairment	0	$ 0	0	$ 0
Proceeds from sale of a cost method investment			0	73,342,000
Gain on sale of a cost method investment	$ 0	$ 0	$ 0	$ 69,373,000

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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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.

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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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The net realized gain (loss) on investments sold during the period, not including gains (losses) on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, which, for cash flow reporting, is a component of proceeds from investing activities.

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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.

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Sum of the carrying amounts as of the balance sheet date of all investments.

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Amount of cash inflow from the sale of investments classified as other.

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