Equity - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2013	Jun. 25, 2014	Jun. 29, 2011
Class of Stock [Line Items]
Common Stock remaining shares authorized for repurchase	0
Purchases of common shares (in shares)	1,722,332
Repurchase of common shares	$ 127,360	$ 128,218	$ 30,417
Purchases and retirement of common shares (in shares)	4,176,187	3,380,500
Deferred compensation obligation credited to common share option	$ 14,560
Stock repurchase on June 25, 2014
Class of Stock [Line Items]
Common Stock remaining shares authorized for repurchase	7,546,145
Purchases of common shares (in shares)	2,453,855
Maximum
Class of Stock [Line Items]
Common Stock shares authorized for repurchase					10,000,000
Maximum | Stock repurchase on June 25, 2014
Class of Stock [Line Items]
Common Stock shares authorized for repurchase				10,000,000