Summary of Accounts Receivable (Detail) (USD $) In Thousands, unless otherwise specified	Nov. 30, 2013	May 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled revenues	$ 24,976	$ 25,516
Allowance for doubtful accounts	(5,141)	(5,438)
Total	184,586	172,108
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts receivable	$ 164,751	$ 152,030