Schedule of Combined Financial Information for Unconsolidated Affiliates (Detail) - Unconsolidated Affiliates - USD ($) $ in Thousands	May 31, 2017	May 31, 2016
Investments in and Advances to Affiliates [Line Items]
Cash	$ 55,541	$ 112,122
Other current assets	559,021	446,796
Noncurrent assets	361,106	352,370
Total assets	975,668	911,288
Current liabilities	156,947	112,491
Short-term borrowings	8,172	11,398
Current maturities of long-term debt	5,827	3,297
Long-term debt	268,711	266,942
Other noncurrent liabilities	21,380	21,034
Equity	514,631	496,126
Total liabilities and equity	$ 975,668	$ 911,288