Investments - Narrative (Details) - USD ($)		3 Months Ended	6 Months Ended
	Jun. 30, 2014	Nov. 30, 2015	Nov. 30, 2015	Nov. 30, 2014	May. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Investments		$ 126,547,000	$ 126,547,000		$ 329,692,000
Cash surrender value of insurance policies		108,800,000	108,800,000		101,800,000
Equity method investments		15,500,000	15,500,000		225,700,000
Cost method investments		2,200,000	2,200,000		$ 2,200,000
Proceeds from sale of business interest in affiliates		$ 578,257,000	578,257,000	$ 0
Dividends received on equity method investment	$ 5,200,000		0	5,247,000
Cash received from sale of equity method investment	$ 35,200,000
Gain on sale of stock of an equity method investment, net of tax				13,600,000
Losses due to impairment			$ 0	$ 0