FAIR VALUE DISCLOSURES - Assets at Fair Value On A Non-recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventories	$ 131,616		$ 131,616		$ 124,911
Assets held for sale	34,934		34,934		$ 38,246
Inventory write-down	0	$ (7,572)	(1,192)	$ (7,572)
Impairment charges on aircraft held for sale	(8,183)	(1,011)	(9,747)	(11,160)
Loss on sale of assets and asset impairment charges	(8,183)	(8,583)	(10,939)	(18,732)
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventories	1,218	56,355	1,218	56,355
Assets held for sale	36,167	40,338	36,167	40,338
Total assets	37,385	96,693	37,385	96,693
Fair Value, Measurements, Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventories	0	0	0	0
Assets held for sale	0	0	0	0
Total assets	0	0	0	0
Fair Value, Measurements, Nonrecurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventories	1,218	56,355	1,218	56,355
Assets held for sale	36,167	40,338	36,167	40,338
Total assets	37,385	96,693	37,385	96,693
Fair Value, Measurements, Nonrecurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventories	0	0	0	0
Assets held for sale	0	0	0	0
Total assets	$ 0	$ 0	$ 0	$ 0