Financial Instruments And Fair Value Measurements - Estimated Fair Values for the Company's Senior Notes and Assets Held by Special Purpose Entities (Detail) - Estimate of Fair Value Measurement - USD ($) $ in Millions	Jul. 31, 2017	Oct. 31, 2016
Senior Notes due 2017
Estimated Fair Value Of Financial Instruments [Line Items]
Estimated fair value	$ 0.0	$ 302.4
Senior Notes due 2019
Estimated Fair Value Of Financial Instruments [Line Items]
Estimated fair value	276.6	280.1
Senior Notes due 2021
Estimated Fair Value Of Financial Instruments [Line Items]
Estimated fair value	$ 282.7	$ 264.9