PROPERTY AND EQUIPMENT AND ASSETS HELD FOR SALE (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2017 USD ($) aircraft	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($) aircraft	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2017 USD ($) aircraft	Mar. 31, 2016 USD ($) aircraft	Mar. 31, 2015 USD ($) aircraft	Mar. 31, 2014 aircraft
Property and equipment [Line Items]
Number of aircraft delivered | aircraft									9	8	21
Capital expenditures									$ 135,110	$ 372,375	$ 601,834
Number of aircraft sold or disposed of | aircraft									14	35	44
Proceeds from asset dispositions									$ 18,471	$ 60,035	$ 414,859
Gain (loss) on disposal of assets	$ (1,400)	$ (900)	$ (2,200)	$ (10,000)	$ (6,800)	$ (2,200)	$ (14,000)	$ (7,700)	(14,499)	(30,693)	(35,849)
Impairment charges on assets held for sale									12,450	$ 29,571	$ 36,057
Number of aircraft sale leaseback | aircraft										3	14
Sale leaseback transaction, gross proceeds										$ 29,200	$ 380,700
Accelerated depreciation									10,400	$ 28,700	10,400
Number of aircraft movement into (out of) deferred sale leaseback advance | aircraft										(2)
Completion of deferred sale leaseback										$ 75,800	183,700
Removal of deferred sale leaseback advance										$ 74,300	182,600
Number of aircraft purchased with short-term borrowings | aircraft										2
Aircraft purchases with short-term borrowings									0	$ 24,394	$ 0
Inventories	$ 124,911				$ 142,503				$ 124,911	$ 142,503
Number of aircraft transferred to held for sale | aircraft	12				35				12	35	15
Property and equipment, gross, period increase (decrease)									$ (19,700)	$ (83,600)	$ (91,500)
Deferred sale leaseback advance									0	$ 18,285	$ 69,680
Number Of Aircraft Assigned Future Payments | aircraft										(2)	(5)	7
Assets held for sale	$ 38,246				$ 43,783				38,246	$ 43,783
Damage from Fire, Explosion or Other Hazard [Member]
Property and equipment [Line Items]
Gain (loss) on disposal of assets											$ 4,900
Insurance Recoveries											16,000
Asia Pacific
Property and equipment [Line Items]
Capital expenditures									$ 15,086	23,745	23,077
Accelerated depreciation										$ 5,300	$ 6,000
Assets held for sale
Property and equipment [Line Items]
Number of aircraft impaired | aircraft									14	16	27
Number of aircraft owned | aircraft	20				22				20	22
Medium aircraft
Property and equipment [Line Items]
Number of aircraft delivered | aircraft									5	1	6
Number of aircraft in exit plan | aircraft									11	18	10
Large aircraft
Property and equipment [Line Items]
Number of aircraft delivered | aircraft									0	3	10
Number of aircraft in exit plan | aircraft										4	4
SAR aircraft
Property and equipment [Line Items]
Number of aircraft delivered | aircraft									4	4	5
Prototype aircraft
Property and equipment [Line Items]
Number of aircraft impaired | aircraft											3
Impairment charges on assets held for sale											$ 4,300
Fixed wing aircraft
Property and equipment [Line Items]
Number of aircraft in exit plan | aircraft										1	1
Aircraft and related equipment
Property and equipment [Line Items]
Capital expenditures									$ 127,447	$ 285,530	$ 476,368
Gain (loss) on disposal of assets									(2,049)	(1,122)	208
Other depreciable assets
Property and equipment [Line Items]
Capital expenditures									7,663	86,845	125,466
Construction in progress
Property and equipment [Line Items]
Capital expenditures									$ 71,400	$ 202,700	440,900
Improper Capitalization Of Profit [Member] | Sales [Member]
Property and equipment [Line Items]
Quantifying Misstatement in Current Year Financial Statements, Amount											(3,500)
Improper Capitalization Of Profit [Member] | Depreciation and amortization
Property and equipment [Line Items]
Quantifying Misstatement in Current Year Financial Statements, Amount											(200)
Improper Capitalization Of Profit [Member] | Cost of Sales [Member]
Property and equipment [Line Items]
Quantifying Misstatement in Current Year Financial Statements, Amount											2,000
Improper Capitalization Of Profit [Member] | Other Noncurrent Assets [Member]
Property and equipment [Line Items]
Quantifying Misstatement in Current Year Financial Statements, Amount											(4,400)
Improper Capitalization Of Profit [Member] | Other Noncurrent Liabilities [Member]
Property and equipment [Line Items]
Quantifying Misstatement in Current Year Financial Statements, Amount											$ 900