Schedule of Combined Financial Information for Unconsolidated Affiliates (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Aug. 31, 2014		Aug. 31, 2013	May 31, 2014
Investments in and Advances to Affiliates [Line Items]
Cash	$ 54,254			$ 52,997
Receivable from partner	14,195	[1]		12,717	[1]
Other current assets	463,909			454,417
Noncurrent assets	291,520			294,001
Total assets	823,878			814,132
Current liabilities	139,973			128,595
Short-term borrowings	28,217			40,992
Current maturities of long-term debt	4,435			4,510
Long-term debt	267,232			268,350
Other noncurrent liabilities	18,869			20,217
Equity	365,152			351,468
Total liabilities and equity	823,878			814,132
Net sales	392,550		423,481
Gross margin	88,751		89,814
Operating income	63,479		64,540
Depreciation and amortization	9,122		10,337
Interest expense	2,162		2,223
Income tax expense	2,753		3,030
Net earnings	$ 59,440		$ 59,634

[1] Represents cash owed from a joint venture partner as a result of centralized cash management.