Shareholders' Equity (Shares Repurchased Under Share Repurchase Program) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Class of Stock [Line Items]
Aggregate purchase price			$ 61.3
Treasury Stock [Member]
Class of Stock [Line Items]
Aggregate purchase price			$ 61.3
Stock Repurchase Program Board Authorized Repurchases [Member]
Class of Stock [Line Items]
Shares repurchased (in shares)	0.8	1.1	0.9	3.6
Aggregate purchase price	$ 50.0	$ 64.1	$ 59.1	$ 179.8
Average purchase price per share (in dollars per share)	$ 62.78	$ 56.05	$ 62.41	$ 50.53
Remaining amount available for share repurchase	$ 221.6		$ 221.6