Debt (Convertible Notes) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010 Convertible Notes Exchange Offer [Member]	Sep. 30, 2011 Convertible Notes Exchange Offer [Member]	Mar. 31, 2011 Convertible Notes Exchange Offer [Member]	Sep. 30, 2010 Convertible Notes [Member]
Principal amount of note					$ 324.7		$ 20.0	$ 345.0
Cash paid in exchange offer					52.0	3.1
Shares issued approximately					37.7	2.3
Fair market value of common stock at settlement						47.4
Fair value of the liability component of Convertible Notes Exchanged							21.8
Carrying value of Convertible Notes exchanged						17.3
Loss related to extinguishment of debt	$ 6.8	$ 0	$ 6.8	$ 4.8		$ 4.8