Revenue Recognition - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013	Apr. 30, 2014
Revenue Recognition [Line Items]
Amounts received for reimbursement of travel and other out-of-pocket expenses	$ 700,000	$ 606,000	$ 1,300,000	$ 1,200,000
Unbilled amounts	2,923,000		2,923,000		3,234,000
Unbilled License Fees
Revenue Recognition [Line Items]
Unbilled amounts	637,000		637,000		1,100,000
Unbilled Services Revenues
Revenue Recognition [Line Items]
Unbilled amounts	$ 2,300,000		$ 2,300,000		$ 2,200,000
Minimum
Revenue Recognition [Line Items]
Contractual period of maintenance contract			1 year
Maximum
Revenue Recognition [Line Items]
Contractual period of maintenance contract			3 years