Fair Value Measures - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2015	Apr. 30, 2014	Oct. 31, 2014
Fair Value Measures [Line Items]
Other-than-temporary impairment	$ 0	$ 0	$ 0	$ 0
Non-marketable equity securities	10.9		10.9		10.9
Cost Method Investments
Fair Value Measures [Line Items]
Non-marketable equity securities	6.7		6.7		6.7
Equity Method Investments
Fair Value Measures [Line Items]
Non-marketable equity securities	$ 4.2		$ 4.2		$ 4.2