Financial Instruments And Fair Value Measurements - Estimated Fair Values for the Company's Senior Notes and Assets Held by Special Purpose Entities (Detail) - USD ($) $ in Millions	Apr. 30, 2018	Oct. 31, 2017
Estimated Fair Value Of Financial Instruments [Line Items]
Assets held by special purpose entities	$ 50.9	$ 50.9
Estimate of Fair Value Measurement
Estimated Fair Value Of Financial Instruments [Line Items]
Assets held by special purpose entities	51.3	52.5
Senior Notes due 2019 | Estimate of Fair Value Measurement
Estimated Fair Value Of Financial Instruments [Line Items]
Estimated fair value	262.2	272.0
Senior Notes due 2021 | Estimate of Fair Value Measurement
Estimated Fair Value Of Financial Instruments [Line Items]
Estimated fair value	$ 287.4	$ 281.0