Redeemable Noncontrolling Interests - Redeemable Noncontrolling Interest (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jul. 31, 2016	Oct. 31, 2017	Oct. 31, 2016
Redeemable Noncontrolling Interest, Equity [Roll Forward]
Redeemable noncontrolling interests, beginning balance		$ 31.8	$ 0.0
Reclassification of book value of noncontrolling interest			12.4
Out-of period mark to redemption value			19.8
Current period mark to redemption value		(0.5)	2.1
Repurchase of redeemable shareholder interest	$ (5.5)		(5.5)
Redeemable noncontrolling interest share of income and other		1.4	4.8
Dividends to redeemable noncontrolling interest and other		(1.2)	(1.8)
Redeemable noncontrolling interests, ending balance		$ 31.5	$ 31.8