Fair Value Measurements (Narrative) (Details) (Swap [Member], USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013 gal	Sep. 30, 2013 Prepaid Expenses And Other Assets [Member]	Dec. 31, 2012 Prepaid Expenses And Other Assets [Member]	Sep. 30, 2013 Accrued Expenses And Other Liabilities [Member]	Dec. 31, 2012 Accrued Expenses And Other Liabilities [Member]
Derivative [Line Items]
Derivative asset (Less than $1 as of September 30, 2013 and December 31, 2012)		$ 1	$ 1
Derivative liability (Less than $1 as of September 30, 2013 and December 31, 2012)				$ 1	$ 1
Fixed price swap contract (in gallons)	7,300,000
Average contract price (in dollars per gallon)	3.88
Average forward price (in dollars per gallon)	3.87