BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Cash Flow Information (Details) - USD ($) $ in Thousands				3 Months Ended	12 Months Ended
	Oct. 01, 2016	Oct. 01, 2015	Oct. 01, 2014	Dec. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Debt Instrument [Line Items]
Decrease in cash and cash equivalents for repayment of debt					$ (5,320)	$ (15,859)	$ (16,646)
Credit Facility | Senior Secured Credit Facility, Tern Loan A and Term Loan B
Debt Instrument [Line Items]
Reduction in notes payable					0	5,179	4,397
Decrease in cash and cash equivalents for repayment of debt	$ 18,600	$ 5,200	$ 4,400
Promissory Notes | 2012 Mohegan Tribe Minor's Trust Promissory Note
Debt Instrument [Line Items]
Reduction in notes payable				$ 6,000	$ 0	$ 6,000	$ 0