BANKRUPTCY AND RELATED MATTERS Reorganization items (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2019 USD ($) aircraft	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) aircraft	Sep. 30, 2018 USD ($)
Debt Instrument [Line Items]
Debtor Reorganization Items, Legal and Advisory Professional Fees	$ 35,462		$ 50,965
Debtor Reorganization Items, Gain (Loss) on Settlement of Other Claims, Net	31,830		31,830
Debtor Reorganization Items, Net Gain (Loss) on Rejection of Leases and Other Executory Contracts	4,170		30,221
Debtor Reorganization Items, Write-off of Debt Discounts	0		30,158
Debtors Reorganization Items, Backstop Commitment Fee	19,250		19,250
Debtor Reorganization Items, Write-off of Debt Issuance Costs	4,114		8,758
Debtor Reorganization Items, Cost on Rejection of Corporate Lease	1,063		1,063
Debtor Reorganization Items, Provision for Expected Allowed Claims	(1,946)		(1,946)
Reorganization Items	$ 93,943	$ 0	$ 170,299	$ 0
Liabilities Subject to Compromise, Number Of Aircraft Lease Rejections | aircraft	10		10
6¼% Senior Notes due 2022 | Senior Notes
Debt Instrument [Line Items]
Debtor Reorganization Items, Write-off of Debt Issuance Costs			$ 2,400
4½% Convertible Senior Notes due 2023 | Convertible Debt
Debt Instrument [Line Items]
Debtor Reorganization Items, Write-off of Debt Discounts			30,200
Debtor Reorganization Items, Write-off of Debt Issuance Costs			2,300
DIP Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Debtor Reorganization Items, Write-off of Debt Issuance Costs	$ 4,100		$ 4,100
S-76C Aircraft
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Number Of Aircraft Lease Rejections | aircraft	9		9
S-76D Aircraft
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Number Of Aircraft Lease Rejections | aircraft	1		1
Aircraft | Large Aircraft [Member]
Debt Instrument [Line Items]
Bankruptcy Claims, Number of Claims on Material Contracts Rejected | aircraft			22