FLEET TRANSITION EXPENSES (DETAILS) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Restructuring Cost and Reserve [Line Items]
Restructuring, Settlement and Impairment Provisions	$ 0	$ 26.8	$ 0	$ 36.9
Horizon Fleet Transition - CRJ-700 [Member]
Restructuring Cost and Reserve [Line Items]
Number of Aircraft Subleased				13
Restructuring, Settlement and Impairment Provisions	0	20.8	0	30.9
Horizon Fleet Transition - Q200 [Member]
Restructuring Cost and Reserve [Line Items]
Number of Aircraft Subleased				16
Restructuring, Settlement and Impairment Provisions	$ 0	$ 6.0	$ 0	$ 6.0