Total Options Outstanding, Range of Exercise Prices and Remaining Contractual Lives (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
	Nov. 30, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
No. of Options	857
Weighted Average Exercise Price	$ 19.28
Weighted Average Remaining Life	2 years 7 months 6 days
$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	105
Weighted Average Exercise Price	$ 9.00
Weighted Average Remaining Life	1 year 2 months 12 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	152
Weighted Average Exercise Price	$ 11.11
Weighted Average Remaining Life	1 year 10 months 24 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	264
Weighted Average Exercise Price	$ 14.51
Weighted Average Remaining Life	2 years 3 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	336
Weighted Average Exercise Price	$ 29.94
Weighted Average Remaining Life	3 years 7 months 6 days