Common Stock - Repurchase Activity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended		6 Months Ended
	May. 31, 2015	[2]	Apr. 30, 2016		Apr. 30, 2015
Equity, Class of Treasury Stock [Line Items]
Total number of shares repurchased (in shares)			0.7	[1]	0.3	[2]
Average price paid per share (in dollars per share)			$ 29.82	[1]	$ 31.92	[2]
Total cash paid for share repurchases			$ 21.5	[1]	$ 10.0	[2]
Cash paid for share repurchase	$ 2.1		21.5		$ 7.9
2015 Share Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Remaining authorized repurchase amount			$ 167.1

[1] At April 30, 2016, authorization for $167.1 million of repurchases remained under our share repurchase program.

[2] Includes $2.1 million of cash paid for share repurchases that settled subsequent to April 30, 2015.