DEBT - Narrative (Details)					3 Months Ended		6 Months Ended		9 Months Ended	12 Months Ended
	Oct. 31, 2019 USD ($)	Oct. 03, 2019 USD ($) Loan	Jul. 24, 2019 USD ($)	May 10, 2019 USD ($)	Sep. 30, 2019 USD ($) subsidiary	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) subsidiary	Sep. 30, 2018 USD ($)	Dec. 31, 2018	Mar. 31, 2019 USD ($)	Aug. 27, 2019 USD ($)	Aug. 12, 2019 USD ($)
Debt Instrument [Line Items]
Long-term Debt, Current Maturities					$ 947,041,000		$ 947,041,000			$ 1,418,630,000
Liabilities Subject to Compromise, Debt and Accrued Interest					554,655,000		554,655,000			0
Proceeds From Rights Offering			$ 385,000,000
Backstop Commitment Agreement					19,250,000		19,250,000			0
Interest paid							37,165,000	$ 48,555,000
Debtor Reorganization Items, Write-off of Debt Discounts					0		30,158,000
Debtor Reorganization Items, Write-off of Debt Issuance Costs					4,114,000		8,758,000
Total debt					1,597,052,000		1,597,052,000			1,448,624,000
Debtor-in-Possession Financing, Borrowings Outstanding											$ 150,000,000
Debtor-in-Possession Financing, Interest Rate on Borrowings Outstanding											8.50%
Common Stock
Debt Instrument [Line Items]
Rights Offering Shares, Percentage			91.825%
Preferred Stock [Member]
Debt Instrument [Line Items]
Rights Offering Shares, Percentage			8.175%
Secured Rights Offering [Member]
Debt Instrument [Line Items]
Proceeds From Rights Offering			$ 347,500,000
Unsecured Rights Offering [Member]
Debt Instrument [Line Items]
Proceeds From Rights Offering			$ 37,500,000
Restatement Adjustment [Member]
Debt Instrument [Line Items]
Long-term Debt, Current Maturities					947,000,000		947,000,000			1,400,000,000
Term Loan [Member]
Debt Instrument [Line Items]
Total debt					$ 75,000,000		$ 75,000,000			$ 0
Term Loan [Member] | 2019 Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 75,000,000
Debt Terms, Period Annual Audit Report To Be Delivered							120 days			90 days
Debt Terms, Period Monthly Unaudited Financial Statements To Be Delivered							20 days			10 days
Term Loan [Member] | 2019 Term Loan [Member] | Eurodollar [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				7.00%
Term Loan [Member] | 2019 Term Loan [Member] | Eurodollar [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	8.00%
Term Loan [Member] | 2019 Term Loan [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				6.00%
Equity Interest Pledged As Collateral, Percentage				35.00%
Term Loan [Member] | 2019 Term Loan [Member] | Base Rate [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	7.00%
Term Loan [Member] | 2019 Term Loan [Member] | Escalation At Six Month [Member] | Eurodollar [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	9.00%
Term Loan [Member] | 2019 Term Loan [Member] | Escalation At Six Month [Member] | Base Rate [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	8.00%
Revolving Credit Facility | ABL Facility
Debt Instrument [Line Items]
Line Of Credit Facility, Number Of Borrowers | subsidiary					2		2
Line of Credit Facility, Current Borrowing Capacity					$ 75,000,000		$ 75,000,000
Line Of Credit Facility, Availability Block Capacity					15,000,000		15,000,000
Line of Credit Facility, Maximum Borrowing Capacity					100,000,000		$ 100,000,000
Terms of debt instruments							5 years
Total debt					0		$ 0
Letters of Credit Outstanding, Amount					15,000,000		15,000,000
Revolving Credit Facility | ABL Facility | Subsequent Event [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 115,000,000
Senior Notes | 8.75% Senior Secured Notes due 2023
Debt Instrument [Line Items]
Equity Interest Pledged As Collateral, Percentage									65.00%
Debt Instrument, Unsolicited Tender Offer Gross Amount												$ 75,000,000
Repayments of Debt					74,800,000
Interest paid					200,000
Total debt					273,449,000		273,449,000			$ 347,400,000
Repayment Of Debt Principal and Interest							75,000,000
Senior Notes | 6¼% Senior Notes due 2022
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Debt and Accrued Interest					415,894,000		415,894,000
Contractual Interest Expense, Total					6,300,000		12,500,000
Contractual Interest Expense on Prepetition Liabilities Not Recognized in Statement of Operations					6,300,000		9,800,000
Debtor Reorganization Items, Write-off of Debt Issuance Costs							2,400,000
Total debt					401,535,000		401,535,000			401,535,000
Convertible Debt | 4½% Convertible Senior Notes due 2023
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Debt and Accrued Interest					146,627,000		146,627,000
Debt Instrument, Face Amount					143,750,000		143,750,000			143,750,000
Total interest expense					0	$ 3,028,000	1,363,000	$ 5,952,000
Contractual Interest Expense, Total					1,600,000		3,200,000
Contractual Interest Expense on Prepetition Liabilities Not Recognized in Statement of Operations					1,600,000		2,500,000
Debtor Reorganization Items, Write-off of Debt Discounts							30,200,000
Debtor Reorganization Items, Write-off of Debt Issuance Costs							2,300,000
Total debt					143,750,000		143,750,000			112,944,000
Secured Debt | Macquarie Debt
Debt Instrument [Line Items]
Total debt					164,028,000		164,028,000			171,028,000
Secured Debt | Macquarie Debt | Subsequent Event [Member]
Debt Instrument [Line Items]
Extension Of Original Maturity Date		12 months
Secured Debt | PK Air Debt
Debt Instrument [Line Items]
Total debt					$ 202,634,000		$ 202,634,000			$ 212,041,000
Secured Debt | PK Air Debt | Subsequent Event [Member] | Omnibus Agreement [Member]
Debt Instrument [Line Items]
Debt Instrument, Number of Loans | Loan		24
Interest Payment Period		6 months
Extension Of Original Maturity Date		18 months
Additional Debt Amount		$ 17,300,000
Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid		$ 104,200,000