Investments (Investments in non-consolidated CLO entities Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2017
Investments [Abstract]
Impairment losses related to investments in non-consolidated CLO entities	$ 0.0	$ 0.2	$ 0.4
Non-Consolidated Collateralized Loan Obligations Details [Line Items]
Non-Consolidated Variable Interest Entity Assets Under Management	400.0	800.0
Investments in non-consolidated CLO entities [Member]
Non-Consolidated Collateralized Loan Obligations Details [Line Items]
Non-Consolidated Variable Interest Entity Assets Under Management	$ 1.4	$ 2.9