Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions		9 Months Ended
	Oct. 27, 2016	Sep. 30, 2016	Sep. 30, 2015
Subsequent Event [Line Items]
Repurchases of common shares (in shares)		844,671	368,468
Share repurchase price (in $ per share)		$ 83.94	$ 122.09
Total cost of treasury shares acquired		$ 72.2	$ 45.0
Stock Purchase Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Repurchases of common shares (in shares)	1,727,746
Share repurchase price (in $ per share)	$ 93.50
Total cost of treasury shares acquired	$ 161.5