Annual report pursuant to Section 13 and 15(d)

Income Taxes - Additional Information (Detail)

v3.7.0.1
Income Taxes - Additional Information (Detail) - USD ($)
 12 Months Ended
Apr. 30, 2017
Apr. 30, 2016
Apr. 30, 2015
Apr. 30, 2014
Schedule Of Income Taxes [Line Items]        
Undistributed earning of foreign subsidiaries $ 359,300,000      
Unrecognized tax benefits liability 2,478,000 $ 2,095,000 $ 2,423,000 $ 2,701,000
Unrecognized tax benefits, reductions resulting from resolution (300,000)      
Unrecognized tax benefits, accrued interest and penalties 0 0    
Unrecognized tax benefits, interest 100,000 $ 100,000 $ 100,000  
Internal Revenue Service (IRS)        
Schedule Of Income Taxes [Line Items]        
Net operating loss carryforward $ 3,600,000      
Net operating loss carryforward, beginning expiration 2028      
State and Local Jurisdiction        
Schedule Of Income Taxes [Line Items]        
Net operating loss carryforward $ 23,300,000      
Net operating loss carryforward, beginning expiration 2018      
Foreign Tax Authority        
Schedule Of Income Taxes [Line Items]        
Net operating loss carryforward $ 108,400,000      
Net operating loss carryforward, beginning expiration 2018      
Tax credit carryforwards $ 3,000,000      
Tax credit carryforwards, expiration 2027