Share-Based Employee Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	6 Months Ended		12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended
	May 31, 2013	May 31, 2013	May 31, 2012	Nov. 30, 2013 Restricted stock	May 31, 2013 Maximum	Nov. 30, 2013 Maximum	May 31, 2013 General and administrative expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period				3 years		10 years
Maximum shares authorized under the Plan	9,600,000	9,600,000
Document Period End Date	May 31, 2013	May 31, 2013
Shares available for grant under the Plan	3,300,000	3,300,000
Share-based Compensation Arrangement By Share-based Payment Award, Options Outstanding, Contractual Term					10 years
Stock options, issued		0
Stock options, exercised		27,500
Restricted stock, issued		179,500
Restricted stock, vested		10,741
Restricted stock, forfeited		7,300
Non-cash stock compensation expense		$ 1.1	$ 2.3				$ 1.1
Unrecognized compensation cost related to non-vested share-based compensation arrangements	3.2	3.2
Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options		$ 0.1