BASIS OF PRESENTATION, CONSOLIDATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Loss on sale of subsidiaries (Details) $ in Thousands, £ in Millions	3 Months Ended		6 Months Ended			12 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 GBP (£)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Mar. 31, 2019 Affiliates
Gain (loss) on sale of subsidiaries	$ 420	$ 0		$ (55,883)	$ 0
Eastern Airways International Limited [Member]
Gain (loss) on sale of subsidiaries	0			(46,852)
Write Off Of Net Assets				35,000
Write Off Of Cumulative Translation Adjustment				11,900
Aviashelf and Bristow Helicopters Leasing Limited [Member]
Gain (loss) on sale of subsidiaries	420			(9,031)
Write Off Of Net Assets				1,800
Write Off Of Cumulative Translation Adjustment				$ 7,200
Eastern Airways [Member]
Disposal Group, Not Discontinued Operation, Consideration Paid | £			£ 17.1
Purchase Covenants, Non Solicitation Of Key Employees Period			12 months	12 months
Purchase Covenants, Right To Appoint Observer To Board Of Directors Period			12 months	12 months
Purchase Covenants, Transition Services Coverage Period			12 months	12 months
Aviashelf Aviation Co. [Member]
Noncontrolling Interest, Ownership Percentage by Parent						48.50%
Proceeds from Divestiture of Businesses	$ 400			$ 2,600
Number Of Joint Ventures | Affiliates						2
Option To Acquire Additional Interest in Affiliate						8.50%
Bristow Helicopter Leasing [Member]
Noncontrolling Interest, Ownership Percentage by Parent						60.00%
Proceeds from Divestiture of Businesses				$ 1,400