Summary of Accounts Receivable (Detail) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2014	May 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled revenues	$ 21,258	$ 14,901
Allowance for doubtful accounts	(4,854)	(4,784)
Total	173,249	175,601
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts receivable	$ 156,845	$ 165,484