Fair Value Measurement (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held and used, long lived, gross	$ 9.8	$ 62.3
Assets held for sale, long lived, gross	5.3	7.1
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets held and used, Impairment charge	5.6	2.0
Long-lived assets held for sale or disposal, Impairment charge	3.8	5.8
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets held and used, Fair value measurement	4.2	60.3
Long-lived assets held for sale or disposal, Fair value measurement	$ 1.5	$ 1.3