Financial Instruments and Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Foreign Currency Forwards [Member]
Derivative activity
Notional amounts at January 1	$ 0		$ 0
New contracts	0		351.7
Acquired contracts	0
Matured or expired contracts	0		(351.7)
Notional amounts at December 31	0		0
Interest Rate Swaps [Member]
Derivative activity
Notional amounts at January 1	268.1	157.7	0
New contracts	0	155.0	157.7
Acquired contracts	1,337.3
Matured or expired contracts	(108.9)	(44.6)
Notional amounts at December 31	1,496.5	268.1	157.7
Interest Rate Cap [Member]
Derivative activity
Notional amounts at January 1	0
New contracts	0
Acquired contracts	25.7
Matured or expired contracts	(25.7)
Notional amounts at December 31	$ 0