Summary of Unaudited Quarterly Consolidated Results of Operations (Detail) - Entity [Domain] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended															12 Months Ended
	May. 31, 2015		Feb. 28, 2015		Nov. 30, 2014		Aug. 31, 2014		May. 31, 2014		Feb. 28, 2014	Nov. 30, 2013		Aug. 31, 2013		May. 31, 2015	May. 31, 2014	May. 31, 2013
Quarterly Financial Information [Line Items]
Net sales	$ 846,023		$ 804,785		$ 871,012		$ 862,414		$ 891,005		$ 773,230	$ 769,900		$ 692,291		$ 3,384,234	$ 3,126,426	$ 2,612,244
Gross margin	110,312		98,491		125,223		129,507		130,836		122,487	128,232		110,964		463,533	492,519	396,643
Impairment of goodwill and long-lived assets	2,344	[1]	81,600	[1]	14,235	[1]	1,950	[1]	22,871	[1]		30,734	[1]	4,641	[1]	100,129	58,246	6,488
Net earnings	30,226		(23,243)		31,455		48,820		31,248		44,211	28,340		56,353		87,256	160,152	136,835
Net earnings (loss) attributable to controlling interest	$ 28,865		$ (25,710)		$ 29,462		$ 44,168		$ 33,163		$ 40,603	$ 22,977		$ 54,557		$ 76,785	$ 151,300	$ 136,442
Earnings (loss) per share - basic	$ 0.45		$ (0.39)		$ 0.44		$ 0.65		$ 0.49		$ 0.59	$ 0.33		$ 0.78		$ 1.16	$ 2.19	$ 1.97
Earnings (loss) per share - diluted	$ 0.44		$ (0.39)		$ 0.43		$ 0.63		$ 0.47		$ 0.57	$ 0.32		$ 0.76		$ 1.12	$ 2.11	$ 1.91

[1] For additional information regarding the Company's impairment charges, refer to "Note C - Goodwill and Other Long-Lived Assets."