Shareholders' Equity (Shares Repurchased Under Share Repurchase Program) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Class of Stock [Line Items]
Aggregate purchase price			$ 6.7
Treasury Stock [Member]
Class of Stock [Line Items]
Aggregate purchase price			6.7
Stock Repurchase Program Board Authorized Repurchases [Member]
Class of Stock [Line Items]
Shares repurchased	0.1	3.7	0.1	15.4
Aggregate purchase price	2.7	126.2	4.9	531.6
Average purchase price per share	$ 42.01	$ 33.99	$ 40.81	$ 34.54
Amount available for share repurchases under the share repurchase program			$ 314.3