DERIVATIVE INSTRUMENTS - INCOME STATEMENT (DETAILS) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Derivative Instruments Not Designated as Hedges [Member] | Fuel hedge contracts [Member] | Gains (losses) recognized in aircraft fuel expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (losses) recognized in income	$ 21.7	$ (82.7)	$ (41.2)	$ (42.6)
Cash Flow Hedging [Member] | Derivative Instruments Designated as Hedges [Member] | Interest rate swaps agreements [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Losses Recognized in Other Comprehensive Income	(3.6)	(19.8)	(9.7)	(24.0)
Cash Flow Hedging [Member] | Derivative Instruments Designated as Hedges [Member] | Interest rate swaps agreements [Member] | Gains (losses) recognized in aircraft rent [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (losses) recognized in income	$ (1.5)	$ (1.5)	$ (4.4)	$ (4.6)