Stockholders' Equity Share Repurchase (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended	9 Months Ended
	Jan. 17, 2017	Jun. 30, 2017	Jun. 30, 2017
Equity, Class of Treasury Stock [Line Items]
Authorized amount of stock for repurchase	$ 500.0
2017 Stock Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Share repurchase authorized date	Jan. 17, 2017
Stock repurchase program expiration date	Jan. 17, 2019
Stock repurchased		$ 128.8	$ 330.5
Stock repurchased (shares)		1.3	3.7
Average price of stock repurchased (in dollars per share)		$ 103.06	$ 90.56
Remaining amount authorized fro stock repurchase		$ 275.9	$ 275.9