Marketable Securities - Additional Information (Detail) (USD $)
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12 Months Ended | |||||||
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Apr. 30, 2013
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Apr. 30, 2012
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Schedule Of Marketable Securities [Line Items] | ||||||||
Trading securities | $ 98,001,000 | [1],[2] | $ 82,176,000 | [1],[2] | ||||
Minimum
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Schedule Of Marketable Securities [Line Items] | ||||||||
Available for sale marketable securities, remaining maturities | 1 month | |||||||
Maximum
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Schedule Of Marketable Securities [Line Items] | ||||||||
Available for sale marketable securities, remaining maturities | 3 years | |||||||
Debt Securities
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Schedule Of Marketable Securities [Line Items] | ||||||||
Gross unrealized gains | 3,100,000 | 3,500,000 | ||||||
Gross unrealized losses | $ 400,000 | |||||||
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X | ||||||||||
- Definition
Available for Sale Securities Contractual Maturity No definition available.
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X | ||||||||||
- Details
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X | ||||||||||
- Definition
The total of financial instruments that are bought and held principally for the purpose of selling them in the near term (thus held for only a short period of time) or for debt and equity securities formerly categorized as available-for-sale or held-to-maturity which the entity held as of the date it opted to account for such securities at fair value. An enterprise may also categorize such a security as trading without the intent to sell it in the near term assuming the decision to categorize the security as trading occurred at acquisition. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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X | ||||||||||
- Definition
The increase (decrease) resulting in a gain from the difference between the fair value and the carrying value, or in the comparative fair values, of trading securities held at each balance sheet date, that was included in earnings for the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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X | ||||||||||
- Definition
The increase (decrease) resulting in a loss from the difference between the fair value and the carrying value, or in the comparative fair values, of trading securities held at each balance sheet date, that was included in earnings for the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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