Auction Rate Securities - Additional Information (Detail) (USD $)	3 Months Ended
Jan. 31, 2012 Entity	Oct. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Number of different issuers the Company held investments in for auction rate securities	4
Investments in auction rate securities	$ 20,000,000
Interest rate revising interval	30 days
Auction rate securities, maturity range, low	2025
Auction rate securities, maturity range, high	2050
Investments in auction rate securities, estimated fair value	18,147,000	15,670,000
Unrealized losses recorded in accumulated other comprehensive loss, before tax	200,000	2,600,000
Unrealized losses recorded in accumulated other comprehensive loss, net of taxes	100,000	1,600,000
Single Issuer Investment
Schedule of Available-for-sale Securities [Line Items]
Investments in auction rate securities	$ 5,000,000

Accumulated appreciation or loss, net of tax, in value of the total of available-for-sale securities at the end of an accounting period.

+ References+ Details

For an unclassified balance sheet, total of debt securities categorized neither as held-to-maturity nor trading.

+ References

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+ Details

- Definition

Total of debt securities categorized neither as held-to-maturity nor trading which are intended be sold or mature more than one year from the balance sheet date or operating cycle, if longer.

+ References

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