Restricted Cash (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Jul. 02, 2010
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash	$ 75.9	$ 100.5
Less: short-term restricted cash	(8.5)	(16.0)
Long-term restricted cash	67.4	84.5
Defeasance of unsecured notes to be issued (see Note 14) [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash	75.4	89.2	89.2
Collateralization of Letters of Credit [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash	0	4.8
Other, Restricted Cash [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash	$ 0.5	$ 6.5