Total Options Outstanding, Range of Exercise Prices and Remaining Contractual Lives (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Aug. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
No. of Options	720
Weighted Average Exercise Price	$ 20.96
Weighted Average Remaining Life	2 years 4 months 24 days
$8.20 to $9.62
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Prices, Lower limit	$ 8.20
Range of Prices, Upper limit	$ 9.62
No. of Options	35
Weighted Average Exercise Price	$ 9.05
Weighted Average Remaining Life	9 months 18 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	96
Weighted Average Exercise Price	$ 11.97
Weighted Average Remaining Life	1 year 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	259
Weighted Average Exercise Price	$ 14.49
Weighted Average Remaining Life	1 year 9 months 18 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	330
Weighted Average Exercise Price	$ 29.92
Weighted Average Remaining Life	3 years 1 month 6 days