Schedule of Combined Financial Information for Unconsolidated Affiliates (Detail) - Unconsolidated Affiliates - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2016	Nov. 30, 2015	Nov. 30, 2016	Nov. 30, 2015	May 31, 2016
Investments in and Advances to Affiliates [Line Items]
Cash	$ 59,751		$ 59,751		$ 112,122
Other current assets	523,625		523,625		446,796
Noncurrent assets	352,117		352,117		352,370
Total assets	935,493		935,493		911,288
Current liabilities	141,808		141,808		112,491
Short-term borrowings	9,210		9,210		11,398
Current maturities of long-term debt	2,807		2,807		3,297
Long-term debt	263,646		263,646		266,942
Other noncurrent liabilities	19,834		19,834		21,034
Equity	498,188		498,188		496,126
Total liabilities and equity	935,493		935,493		$ 911,288
Net sales	387,192	$ 389,185	804,307	$ 793,648
Gross margin	96,541	84,767	220,738	173,785
Operating income	67,365	55,810	161,762	117,057
Depreciation and amortization	6,973	8,068	13,793	16,165
Interest expense	2,151	2,136	4,299	4,295
Income tax expense	3,545	2,164	11,063	4,723
Net earnings	$ 63,444	$ 71,144	$ 149,511	$ 134,070