BASIS OF PRESENTATION, CONSOLIDATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Loss on impairment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2018	Mar. 31, 2018
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of inventories	$ 0	$ 0	$ 9,276	$ 1,192
Impairment of property and equipment	0	0	104,939	0
Impairment of intangible assets	0	0	3,005	0
Loss on impairment	0	0	117,220	1,192
Property and equipment, net	1,847,543		1,847,543			$ 2,068,020
Payments for Flight Equipment	$ 0	$ 0	0	2,300
H225 Aircraft [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of inventories			8,900
Impairment of property and equipment			87,500
Property and equipment, net					$ 116,400
Oil and Gas Properties [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of property and equipment			0
Eastern Airways [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of inventories			300
Impairment of property and equipment			17,500
Impairment of intangible assets			$ 3,005
Assets, Fair Value Disclosure					$ 20,500
Training Aircraft [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of inventories				$ 1,200