DERIVATIVE INSTRUMENTS (TABLES)

12 Months Ended

Dec. 31, 2011

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]

Fair values of derivative instruments on the consolidated balance sheet as of December 31 (in millions):

	2011			2010
Derivative Instruments Not Designated as Hedges
Fuel hedge contracts
Fuel hedge contracts, current assets	$	46.7		$	61.4
Fuel hedge contracts, noncurrent assets	70.2			69.9
Fuel hedge contracts, current liabilities	(10.3		)	$	—
Derivative Instruments Designated as Hedges
Interest rate swaps
Other accrued liabilities	(5.2		)	(6.0		)
Other liabilities	(23.6		)	(2.8		)
Gains (losses) in AOCL	20.0			(11.2		)

Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance [Table Text Block]

Pretax effect of derivative instruments on earnings (fuel hedges) and AOCL (interest rate swaps) at December 31 (in millions):

	2011			2010			2009
Derivative Instruments Not Designated as Hedges
Fuel hedge contracts
Gains (losses) recognized in aircraft fuel expense	$	(8.7	)	$	(2.0	)	$	28.1
Derivative Instruments Designated as Hedges
Interest rate swaps
Gains (losses) recognized in aircraft rent	(6.2		)	(6.1		)	(1.6		)