Quarterly report pursuant to Section 13 or 15(d)

Amortized Cost and Fair Values of Marketable Securities Classified as Available-For-Sale Investments (Detail)

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Amortized Cost and Fair Values of Marketable Securities Classified as Available-For-Sale Investments (Detail) - USD ($)
$ in Thousands
Oct. 31, 2015
Apr. 30, 2015
Schedule of Available-for-sale Securities [Line Items]    
Estimated Fair Value [1] $ 2,003 $ 13,177
Corporate Bonds    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 2,003 13,167
Gross Unrealized Gains   11
Gross Unrealized Losses [2]   (1)
Estimated Fair Value [1] $ 2,003 $ 13,177
[1] The Company's financial assets measured at fair value on a recurring basis include trading securities classified as Level 1 and available-for-sale securities classified as Level 2. As of October 31, 2015 and April 30, 2015, the Company had no investments classified as Level 3.
[2] There are no marketable securities that have been in a continuous unrealized loss position for 12 months or more.