LONG-TERM DEBT - Schedule of Long-term Debt Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019	Oct. 31, 2016
Debt Schedule [Abstract]
Long-term debt	$ 1,970,010	$ 1,909,157
Less: current portion of long-term debt	(75,355)	(76,909)
Long-term debt, net of current portion	1,894,655	1,832,248
Credit Facility | Senior Secured Credit Facility - Revolving
Debt Schedule [Abstract]
Long-term debt	197,000	102,000
Credit Facility | Senior Secured Credit Facility - Term Loan A
Debt Schedule [Abstract]
Long-term debt	227,710	263,829
Debt issuance costs	4,199	4,236
Credit Facility | Senior Secured Credit Facility - Term Loan B
Debt Schedule [Abstract]
Long-term debt	792,829	805,394
Debt issuance costs	20,809	16,925
Credit Facility | 2016 7 7/8% Senior Unsecured Notes
Debt Schedule [Abstract]
Long-term debt	491,821	490,435
Credit Facility | MGE Niagara Resorts Credit Facility - Revolving
Debt Schedule [Abstract]
Long-term debt	26,187	0
Credit Facility | MGE Niagara Credit Facility - Term Loan
Debt Schedule [Abstract]
Long-term debt	69,297	73,564
Debt issuance costs	847	1,002
Credit Facility | Mohegan Expo Credit Facility
Debt Schedule [Abstract]
Long-term debt	27,750	29,357
Debt issuance costs	658	925
Credit Facility | Guaranteed Credit Facility
Debt Schedule [Abstract]
Long-term debt	29,529	31,840
Debt issuance costs	877	1,191
Credit Facility | Mohegan Tribe Subordinated Loan
Debt Schedule [Abstract]
Long-term debt	5,000	0
Convertible Debenture | MGE Niagara Resorts Convertible Debenture
Debt Schedule [Abstract]
Long-term debt	29,928	30,204
Notes payable to banks | Redemption note payable
Debt Schedule [Abstract]
Long-term debt	69,099	81,329
Debt issuance costs	$ 15,701	23,905
Senior Unsecured Notes | 2016 7 7/8% Senior Unsecured Notes
Debt Schedule [Abstract]
Note stated interest rate	7.875%		7.875%
Debt issuance costs	$ 8,179	9,565
Senior Unsecured Notes | Other
Debt Schedule [Abstract]
Long-term debt	$ 3,860	$ 1,205