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Goodwill and Intangible Assets - Additional Information (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 6 Months Ended
Oct. 31, 2014
Oct. 31, 2013
Oct. 31, 2014
Oct. 31, 2013
Goodwill and Intangible Assets Disclosure [Abstract]        
Intangible amortization expenses $ 737 $ 586 $ 1,474 $ 1,109