Changes in Cost Basis and Fair Value of Auction Rate Securities (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Jan. 31, 2013		Oct. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Balance at ending of year	$ 17,832	[1]	$ 17,780	[1]
Cost Basis | Auction Rate Securities
Schedule of Available-for-sale Securities [Line Items]
Balance at beginning of year	17,994		18,307
Unrealized gains included in accumulated other comprehensive loss
Other-than-temporary credit loss recognized in earnings			(313)
Balance at ending of year	17,994		17,994
Fair Value, Inputs, Level 3 | Auction Rate Securities
Schedule of Available-for-sale Securities [Line Items]
Balance at beginning of year	17,780		15,670
Unrealized gains included in accumulated other comprehensive loss	52		2,110
Balance at ending of year	$ 17,832		$ 17,780

[1] As of January 31, 2013, the Company held investments in auction rate securities from four different issuers having an original principal amount of $5.0 million each (aggregating to $20.0 million). For investments in auction rate securities that were not redeemed or had no market activity indicative of value, the fair value was based on discounted cash flow valuation models, primarily utilizing unobservable inputs. See Note 6, "Auction Rate Securities," for the roll-forwards of assets measured at fair value using significant unobservable Level 3 inputs and the sensitivity analysis of significant inputs. Subsequently, on February 8, 2013, one of the auction rate securities was redeemed by the issuer at its par value of $5.0 million. For that particular security, the fair value as of January 31, 2013 was determined to be the same as its par value.