Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Jan. 31, 2015 Customer	Jan. 31, 2014 Customer	Jan. 31, 2015 Customer	Jan. 31, 2014 Customer	Apr. 30, 2014 Customer
Significant Accounting Policies [Line Items]
Number of clients that accounted for more than 10% of account receivables	0		0		0
Number of clients that accounted for more than 10% of revenue	0	0	0	0
Impairment charges recognized related to short-term investments	$ 0		$ 0
Capitalized internal-use software development costs
Significant Accounting Policies [Line Items]
Estimated useful life			3 years