Combined Financial Results for Unconsolidated Affiliates (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Aug. 31, 2012	Aug. 31, 2011
Investments in and Advances to Affiliates [Line Items]
Net sales	$ 446,853	$ 427,794
Gross margin	77,918	83,825
Operating income	51,711	57,147
Depreciation and amortization	8,990	4,834
Interest expense	2,261	876
Income tax expense	3,469	4,358
Net earnings	$ 46,284	$ 51,865