Auction Rate Securities - Additional Information (Detail) (USD $)	3 Months Ended							1 Months Ended
	Jan. 31, 2013 Entity		Oct. 31, 2012		Jan. 31, 2013 Auction Rate Securities	Oct. 31, 2012 Auction Rate Securities	Jan. 31, 2013 Single Issuer Investment	Feb. 08, 2013 Subsequent Event
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						$ 5,000,000
Interest rate revising interval	30 days
Auction rate securities, earliest maturity period	2033
Auction rate securities, latest maturity period	2050
Auction rate securities, redeemed								5,000,000
Auction rate securities, at fair value	5,000,000
Investments in auction rate securities, estimated fair value	17,832,000	[1]	17,780,000	[1]
Auction rate security, at fair value, that was not in unrealized loss position					13,000,000	10,000,000
Auction rate securities, continuous unrealized loss position, less than twelve months, fair value					4,800,000	7,800,000
Unrealized losses recorded in accumulated other comprehensive loss, before tax	200,000		200,000
Unrealized losses recorded in accumulated other comprehensive loss, net of taxes	$ 100,000		$ 100,000

[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.