Equity Share Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended		8 Months Ended
	Aug. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018
Equity, Class of Treasury Stock [Line Items]
Shares repurchased		$ 54.0	$ 55.7
2017 Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Maximum amount of share repurchase program	$ 800.0
Expiration date of share repurchase program	Jun. 30, 2020
Shares repurchased (shares)		500,033		2,919,502
Shares repurchased		$ 54.0		$ 309.2
Average price of shares repurchased		$ 108.00		$ 105.91
2017 Share Repurchase Program [Member] | Accelerated Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Maximum amount of share repurchase program	$ 200.0