COWLITZ PROJECT (Details) - USD ($) $ in Thousands				1 Months Ended	12 Months Ended
	Jan. 01, 2019	Dec. 04, 2018	Dec. 15, 2017	May 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Apr. 30, 2017
Schedule of Long-term Development Projects [Line Items]
Total consideration of membership interest					$ 10,000	$ 0	$ 0
Development fees revenue					$ 976	570	7,300
Management fee (as a percent)					24.00%
Management fees					$ 27,900	13,500	$ 6,000
Mohegan Tribe
Schedule of Long-term Development Projects [Line Items]
Total consideration of membership interest	$ 10,000
Salishan-Mohegan, LLC
Schedule of Long-term Development Projects [Line Items]
Accounts receivables, related party						$ 104,400
Cowlitz Tribal Gaming Authority | Salishan-Mohegan, LLC
Schedule of Long-term Development Projects [Line Items]
Repayments of related party debt		$ 106,600
Amount received from related parties		32,000
Interest receivable		$ 74,600
Cowlitz Project | Salishan-Mohegan, LLC
Schedule of Long-term Development Projects [Line Items]
Annual rate of interest accrued						13.00%
Redemption note payable | Notes payable to banks
Schedule of Long-term Development Projects [Line Items]
Redemption price of membership interest								$ 114,800
Redemption liability								$ 68,500
Equal monthly installments			$ 1,900	$ 1,900
Periodic payment of debt instrument				5 years	5 years
Salishan-Mohegan and Cowlitz Project
Schedule of Long-term Development Projects [Line Items]
Ownership interest (as a percent)					100.00%