Fair Value Measurements (Assets and Liabilities Measured at Fair Value) (Details) (USD $)						12 Months Ended
	Dec. 31, 2013 4 percent Convertible Senior Notes [Member]	Dec. 31, 2012 4 percent Convertible Senior Notes [Member]	Dec. 31, 2011 4 percent Convertible Senior Notes [Member]	Nov. 30, 2009 4 percent Convertible Senior Notes [Member]	Dec. 31, 2013 Capital Leases [Member]	Dec. 31, 2013 Swap [Member] gal	Dec. 31, 2013 Accrued Expenses And Other Liabilities [Member] Swap [Member]	Dec. 31, 2012 Accrued Expenses And Other Liabilities [Member] Swap [Member]	Dec. 31, 2013 Prepaid Expenses And Other Assets [Member]	Dec. 31, 2012 Prepaid Expenses And Other Assets [Member]	Dec. 31, 2013 Prepaid Expenses And Other Assets [Member] Swap [Member]	Dec. 31, 2012 Prepaid Expenses And Other Assets [Member] Swap [Member]
Derivative [Line Items]
Derivative liability (Less than $1 as of December 31, 2013 and December 31, 2012)							$ 1,000,000	$ 1,000,000
Derivative asset (Less than $1 as of December 31, 2013 and December 31, 2012)									1,000,000	1,000,000	1,000,000	1,000,000
Derivative, nonmonetary notional amount (in gallons)						6,900,000
Derivative, notional amount (in dollars per gallon)						3.89
Average forward price (in dollars per gallon)						3.98
Stated interest rate	4.00%	4.00%	4.00%	4.00%
Effective interest rate	6.60%				7.00%
Debt instrument convertible if converted value	$ 1,094,000,000