OPERATIONS, BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Narrative (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2018 USD ($)	Mar. 31, 2019 USD ($) Customer aircraft Affiliates	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Jun. 30, 2019 USD ($)	May 10, 2019	Jan. 31, 2018	Feb. 06, 2014
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Number of aircraft operated | aircraft		378
Cash collateral for letters of credit		$ 700	$ 19,800
Deferred Set-up Costs, Current		9,800	10,800
Amortization of Other Deferred Charges		10,100	11,400
Goodwill		18,436	19,907	$ 19,798
Accumulated goodwill impairment		50,861
Deferred Tax Assets, Net, Noncurrent		52,000	42,600
Deferred Set-up Costs, Noncurrent		37,100	50,600
Property and equipment		1,834,180	2,068,020
Impairment of aircraft and equipment		104,939	0	0
Impairment of inventories		9,276	5,717	7,572
Impairments of other intangible assets		3,005	0	0
Impairment of goodwill		0	0	8,706
Impairment of investment in unconsolidated affiliates		0	85,683	0
Other accrued liabilities		38,679	65,978
Foreign Currency Transaction Gain (Loss), before Tax		(5,200)	(2,600)	(2,900)
Redeemable non controlling interest, carrying amount, period increase (decrease)			6,121
Adjustments to Additional Paid in Capital, Other			(40,393)
Net cash provided by (used in) operating activities		(109,437)	(19,544)	11,537
Accounting Standards Update 2016-16 [Member] | Retained Earnings
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		1,700
Accounting Standards Update 2017-07 [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results			(100)	900
Scenario, Forecast [Member] | Accounting Standards Update 2016-02 [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Operating Lease, Right-of-Use Asset					$ 270,000
Operating Lease, Liability					$ 290,000
Inventory Valuation Reserve
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Additional allowances		2,140	6,355	1,617
Impairment of inventories		0	$ 0	7,572
Europe Caspian
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Accumulated goodwill impairment		33,883
Africa
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Accumulated goodwill impairment		6,179
Corporate and other
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Accumulated goodwill impairment		$ 10,223
Norway
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Number Of Client Contracts | Customer		2
Lider
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Impairment of investment in unconsolidated affiliates		$ 85,700
Business acquisition, percentage of voting interests acquired		20.00%	20.00%
Equity Method Investment, Ownership Percentage		41.90%	41.90%
H225 Aircraft [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Property and equipment	$ 116,400
Impairment of aircraft and equipment	87,500	$ 87,500
Impairment of inventories	8,900	8,900
Eastern Airways [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Impairment of aircraft and equipment		17,500
Impairment of inventories		300	$ 4,500
Impairments of other intangible assets		$ 3,000
Impairment of goodwill			8,700
Assets, Fair Value Disclosure	$ 20,500
Bristow Academy
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Impairment of inventories			1,200
Unconsolidated affiliates
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Number of aircraft operated | Affiliates		110
Foreign Currency Transaction Gain (Loss), before Tax		$ (4,200)	(2,000)	$ (3,200)
Columbia Helicopters, Inc [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Cash Outflow for Termination of Business Acquisition		$ 20,000
Eastern Airways
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Number of aircraft operated | aircraft		31
Business acquisition, percentage of voting interests acquired							40.00%	60.00%
Redeemable non controlling interest, carrying amount, period increase (decrease)			$ 6,121
Subsequent Event [Member] | 8.75% Senior Secured Notes | Senior Notes
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Restructuring Support Agreement, Percentage of Holders						99.30%
Subsequent Event [Member] | 6¼% Senior Notes | Senior Notes
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Restructuring Support Agreement, Percentage of Holders						73.60%