Common Stock - Repurchase Activity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	6 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Equity [Abstract]
Total number of shares purchased (in shares)	0.2	0.7
Average price paid per share (in usd per share)	$ 40.07	$ 29.82
Total cash paid for share repurchases	$ 7.9	$ 21.5