BANKRUPTCY AND RELATED MATTERS Liabilities Subject To Compromise (Details) $ in Thousands	Sep. 30, 2019 USD ($) aircraft	Mar. 31, 2019 USD ($)
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Debt and Accrued Interest	$ 554,655	$ 0
Liabilities Subject to Compromise, Employee and Deemed Claims	1,983
Liabilities subject to compromise	624,867	0
Total debt	$ 1,597,052	1,448,624
Liabilities Subject to Compromise, Number Of Aircraft Lease Rejections | aircraft	10
Lease Rejections [Member]
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Early Contract Termination Fees	$ 35,000
Milestone Omnibus Agreement [Member]
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Early Contract Termination Fees	20,063
Corporate Office Lease [Member]
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Early Contract Termination Fees	$ 5,300
S-76C Aircraft
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Number Of Aircraft Lease Rejections | aircraft	9
S-76D Aircraft
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Number Of Aircraft Lease Rejections | aircraft	1
H225 Aircraft
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Number Of Aircraft Lease Rejections | aircraft	4
Senior Notes | 6¼% Senior Notes due 2022
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Debt and Accrued Interest	$ 415,894
Total debt	401,535	401,535
Interest Payable	14,400
Convertible Debt | 4½% Convertible Senior Notes due 2023
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Debt and Accrued Interest	146,627
Total debt	143,750	$ 112,944
Interest Payable	$ 2,900