Fair Value Measurements (Narrative) (Details) (Fair Value, Measurements, Nonrecurring [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 24, 2012	Mar. 26, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of long-lived assets which were impaired during the period	$ 17.2	$ 10.7
Impairment charge	13.5	7.1
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of long-lived assets which were impaired during the period	$ 3.7	$ 3.6