Summary of Accounts Receivable (Detail) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2013	May 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled revenues	$ 26,795	$ 25,516
Allowance for doubtful accounts	(5,742)	(5,438)
Total	167,015	172,108
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts receivable	$ 145,962	$ 152,030