Fair Value and Carrying Value of Financial Instruments and Long-Term Debt (Detail) - USD ($) $ in Thousands	Feb. 29, 2020	May 31, 2019
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 212,242	$ 223,168
Marketable equity securities	89,215	87,525
Marketable debt securities	25,490	25,009
Long-term debt, including current portion	2,559,763	2,525,908
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	212,242	223,168
Marketable equity securities	89,215	87,525
Marketable debt securities	25,490	25,009
Long-term debt, including current portion	$ 2,725,297	$ 2,526,817