Income Taxes (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
INCOME TAXES [Abstract]
Effective income tax rate, continuing operations	27.20%	35.40%	27.20%	36.50%
Tax credits percentage of qualified maintenance expenditures to reduce federal income tax			50.00%
Tax credits limitation per mile on maintenance expenditures to reduce federal income tax			$ 3,500