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Marketable Securities (Summary Of Assets Measured At Fair Value On Recurring Basis Using Significant Unobservable Inputs) (Details) (USD $)
In Thousands, unless otherwise specified |
3 Months Ended | 9 Months Ended | ||
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Jan. 31, 2012
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Jan. 31, 2011
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Jan. 31, 2012
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Jan. 31, 2011
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| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
| Balance, beginning of period | $ 71,363 | |||
| Realized gain included in operations | (1,954) | 4,187 | ||
| Sale of securities | (35,466) | (23,453) | ||
| Balance, end of period | 80,500 | 80,500 | ||
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Auction Rate Securities [Member]
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| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
| Balance, beginning of period | 8,200 | |||
| Auction rate securities put option | (745) | |||
| Realized gain included in operations | 745 | |||
| Sale of securities | (8,200) | |||
| Balance, end of period | ||||
| X | ||||||||||
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- Definition
Auction Rate Securities Put Option No definition available.
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| X | ||||||||||
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- Details
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| X | ||||||||||
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- Definition
This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The cash inflow associated with the aggregate amount received by the entity through sale or maturity of marketable securities (held-to-maturity or available-for-sale) during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- 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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