COMMITMENTS AND CONTINGENCIES (Details) (USD $)	3 Months Ended			6 Months Ended		12 Months Ended		6 Months Ended			3 Months Ended				1 Months Ended	3 Months Ended		1 Months Ended	3 Months Ended
	Dec. 31, 2012 number	Sep. 30, 2012 number	Sep. 30, 2011	Sep. 30, 2012 number	Sep. 30, 2011	Mar. 31, 2012	Mar. 31, 2012 Sale Leaseback Previously Included In Construction In Progress [Member]	Sep. 30, 2012 Fiscal Year 2013 To Fiscal Year 2015 [Member] number	Sep. 30, 2012 Fiscal Year 2016 To Fiscal Year 2018 [Member] number	Sep. 30, 2012 Fiscal Year 2023 [Member] number	Dec. 31, 2012 United Kingdom Location [Member] number	Dec. 31, 2012 Nigeria Location [Member] number	Dec. 31, 2012 Norway Location [Member] number	Dec. 31, 2012 Australia Location [Member] number	Nov. 07, 2012 Commitments [Member] number	Sep. 30, 2012 Commitments [Member] number	Jun. 30, 2012 Commitments [Member] number	Nov. 07, 2012 Options [Member] number	Sep. 30, 2012 Options [Member] number	Jun. 30, 2012 Options [Member] number	Sep. 30, 2012 Remainder of Year 2013 [Member] number	Sep. 30, 2012 Year 2014 [Member] number	Sep. 30, 2012 Year 2015 [Member] number	Sep. 30, 2012 Year 2016 [Member] number	Sep. 30, 2012 Year 2017 and Thereafter [Member] number
Aircraft Purchase Contracts [Line Items]
Aircraft Purchase Commitments - Total		$ 687,829,000		$ 687,829,000																	$ 269,593,000	$ 267,427,000	$ 106,456,000	$ 30,582,000	$ 13,771,000
Aircraft Purchase Options - Total		1,166,166,000		1,166,166,000																	7,037,000	84,265,000	372,833,000	338,874,000	363,157,000
Number of aircraft purchase commitments - Large		30		30																	7	13	7	2	1
Number of aircraft purchase commitments - Total		30		30																	7	13	7	2	1
Number of aircraft purchase options - Medium		12		12																	0	0	6	6	0
Number of aircraft purchase options - Large		37		37																	0	0	9	11	17
Number of aircraft purchase options - Total		49		49																	0	0	15	17	17
Number of signed client contracts		7		7
Number of contingent aircraft orders		6		6
Number of aircraft purchase contracts - subsequent event															10			16
Aircraft purchase contracts - subsequent event															275,000,000			470,000,000
Analysis Of Aircraft Orders And Options [Line Items]
Beginning of quarter															20	17	15	33	36	40
Aircraft delivered															0	0	(2)	0	0	0
Aircraft ordered															10	0	0	0	0	0
New options															0	0	0	16	0	0
Exercised options															0	3	4	0	(3)	(4)
End of quarter															30	20	17	49	33	36
Number of aircraft purchased	7			1
Number of aircraft suspend operations	16										11	1	1	3
Sale Leaseback Transaction [Line Items]
Number of aircraft sale leaseback				2		7	2
Sale price of the aircraft leaseback				50,400,000		147,800,000	23,400,000
Lease term of the aircraft				The aircraft leases range from base terms of 60 to 72 months with renewal options of up to 72 months in some cases, include purchase options upon expiration and some include early purchase options.
Monthly Rent payment				3,240,000				1,010,000	1,880,000	350,000
Number of leased aircraft		25		25				6	10	9
Operating leases rental expense		15,300,000	9,100,000	31,600,000	18,100,000
Collective Bargaining Agreements and/or Unions		49.00%		49.00%
Employee Agreement Escalation Rate				up to 12%
Work force reductions costs				2,200,000
Officer Compensation Expense				$ 2,000,000
Possible litigation damages from early termination of agreement				The claimants allege that an agreement between the parties was terminated without justification and seek damages of $16.3 million.
Description of Guarantees Given by Parent Company				We had guaranteed the repayment of up to £10 million ($16.1 million) of the debt of FBS Limited, an unconsolidated affiliate, which has been repaid. Therefore, as of September 30, 2012 we are no longer a guarantor of this debt.