Fair Value Measurement (Assets Measured at Fair Value on a Nonrecurring Basis) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets held and used, Impairment charge				$ 0.6	$ 12.1	$ 5.2	$ 15.7
Long-lived assets held for sale or disposal, Impairment charge				0.9	12.4	14.9	27.3
Total, Impairment charge	19.6	43.0		1.5	24.5	20.1	43.0
Long-lived assets held and used, Fair value measurement								1.2	3.4	4.6	71.9
Long-lived assets held and used, Net book value				3.9	66.5	3.9	66.5
Long-lived assets held for sale or disposal, Fair value measurement									2.3	5.4	3.6
Long-lived assets held for sale or disposal, Net book value				5.4	3.4	5.4	3.4
Total, Fair value measurement								1.2	5.7	10.0	75.5
Total assets	$ 8,303.9	$ 8,905.9	$ 8,281.7	$ 9.3	$ 69.9	$ 9.3	$ 69.9