Stockholders' Equity - Schedule of Share Repurchases (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
Jul. 31, 2020	Apr. 30, 2020	Jul. 31, 2019	Jan. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Stockholders' Equity Note [Abstract]
Number of shares (in shares)	0		0		160,850	24,500
Average repurchase price per share (in dollars per share)					$ 296.9	$ 248.7
Total costs of shares repurchased (in millions)		$ 47.8		$ 6.1	$ 47.8	$ 6.1

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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