BASIS OF PRESENTATION, CONSOLIDATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Loss on impairment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of inventories	$ 9,276	$ 0	$ 9,276	$ 1,192
Impairment of property and equipment	104,939	0	104,939	0
Impairment of intangible assets	3,005	0	3,005	0
Loss on impairment	117,220	$ 0	117,220	1,192
Property and equipment, net	1,886,265		1,886,265		$ 2,068,020
H225 Aircraft [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of inventories	8,900		8,900
Impairment of property and equipment	87,500		87,500
Property and equipment, net	116,400		116,400
Oil and Gas Properties [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of property and equipment	0		0
Eastern Airways [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of inventories	300		300
Impairment of property and equipment	17,500		17,500
Impairment of intangible assets	3,000		3,005
Assets, Fair Value Disclosure	$ 20,500		$ 20,500
Training Aircraft [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of inventories				$ 1,200