Total Options Outstanding, Range of Exercise Prices and Remaining Contractual Lives (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	May 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
No. of Options	1,052
Weighted Average Exercise Price	$ 20.24
Weighted Average Remaining Life	3 years 6 months
$6.42 to $9.62
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Prices, Lower limit	$ 6.42
Range of Prices, Upper limit	$ 9.62
No. of Options	122
Weighted Average Exercise Price	$ 8.92
Weighted Average Remaining Life	1 year 10 months 24 days
$9.63 to $12.82
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Prices, Lower limit	$ 9.63
Range of Prices, Upper limit	$ 12.82
No. of Options	157
Weighted Average Exercise Price	$ 11.10
Weighted Average Remaining Life	2 years 8 months 12 days
$12.83 to $16.03
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Prices, Lower limit	$ 12.83
Range of Prices, Upper limit	$ 16.03
No. of Options	308
Weighted Average Exercise Price	$ 14.56
Weighted Average Remaining Life	3 years 1 month 6 days
$16.04 to $32.05
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Prices, Lower limit	$ 16.04
Range of Prices, Upper limit	$ 32.05
No. of Options	465
Weighted Average Exercise Price	$ 30.05
Weighted Average Remaining Life	4 years 4 months 24 days