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NEW ACCOUNTING STANDARDS - Contract with Customers (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Oct. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract assets	$ 53,200
Contract related liabilities	71,248			$ 63,142
Net cash flows used in investing activities	(143,580)	$ (144,816)	$ (103,234)
Outstanding gaming chips and slot tickets liability
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract related liabilities	7,968			3,298
Loyalty points deferred revenue liability
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract related liabilities	40,968			42,314
Patron advances and other liability
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract related liabilities	22,312			$ 17,530
Mohegan Sun Pocono
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract related liabilities	$ 18,000
Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash flows used in investing activities		$ 28,900	$ 49,500