Fair Value Measurements (Narrative) (Details) (Swap [Member], USD $) In Millions, unless otherwise specified	Sep. 30, 2012 gal	Dec. 31, 2011 Accrued Expenses And Other Liabilities [Member]	Sep. 30, 2012 Maximum [Member] Prepaid Expenses And Other Assets [Member]
Derivative [Line Items]
Derivative asset			$ 1
Derivative liability		$ 1
Fixed price swap contract (in gallons)	7,100,000
Average contract price (in dollars per gallon)	3.92
Average forward price (in dollars per gallon)	3.95