Amortized Cost and Fair Values of Marketable Securities Classified as Available-For-Sale Investments (Parenthetical) (Detail) - USD ($) |
Oct. 31, 2015 |
Apr. 30, 2015 |
|---|---|---|
| Schedule of Available-for-sale Securities [Line Items] | ||
| Marketable securities that have been in a continuous unrealized loss position for 12 months or more | $ 0 | $ 0 |
| X | ||||||||||
- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for twelve months or longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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