PROPERTY AND EQUIPMENT, ASSETS HELD FOR SALE AND OEM COST RECOVERIES Narrative (Details) $ in Thousands	12 Months Ended
	Mar. 31, 2018 USD ($) aircraft	Mar. 31, 2017 USD ($) aircraft	Mar. 31, 2016 USD ($) aircraft	Mar. 31, 2015 USD ($)
Property and equipment [Line Items]
Restructuring and Related Cost, Accelerated Depreciation | $		$ 10,400	$ 28,700
Number Of Aircraft Movement Into (Out Of) Deferred Sale Leaseback Advance			(2)
Deferred Sale Leaseback Completion And Interim Lease Payments | $			$ 75,800	$ 183,700
Removal of Deferred Sale Leaseback Advance | $			$ 74,300	$ 182,600
Number Of Aircraft Purchased With Short-Term Borrowings			2
Number of aircraft transferred to held for sale	4	12	35
Aircraft purchased with short-term borrowings | $	$ 0	$ 0	$ 24,394
Property, Plant and Equipment, Gross, Period Increase (Decrease) | $	$ (9,300)	$ (19,700)	$ (83,600)
Medium Aircraft
Property and equipment [Line Items]
Number Of Aircraft In Exit Plan		11	18
Large Aircraft
Property and equipment [Line Items]
Number Of Aircraft In Exit Plan			4
Fixed wing aircraft
Property and equipment [Line Items]
Number Of Aircraft In Exit Plan			1