MOHEGAN VENTURES-NORTHWEST, LLC (COWLITZ PROJECT) (Details) $ in Thousands	1 Months Ended			3 Months Ended		6 Months Ended
	Apr. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2015 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2017 USD ($) gaming_machine table_game	Mar. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2006 a
Schedule of Long-term Development Projects [Line Items]
Development fees				$ 2,200	$ 1,300	$ 4,000	$ 5,800
Salishan-Mohegan, LLC | Affiliates
Schedule of Long-term Development Projects [Line Items]
Receivables and accrued interest				86,600		86,600		$ 81,900
Reserve for doubtful collections				$ 17,300		$ 17,300		$ 16,400
Salishan-Mohegan, LLC | Cowlitz Tribe
Schedule of Long-term Development Projects [Line Items]
Additional receivable recorded	$ 344
Cowlitz Project | Salishan-Mohegan, LLC
Schedule of Long-term Development Projects [Line Items]
Development fee						3.00%
Area of land purchased (in acres) | a									156
Term of management agreement						7 years
Management fee						24.00%
Accounts receivable repaid		$ 19,400
Notes receivable term		7 years
Additional interest rate (as a percent)		1.00%
Financing rate (as a percent)		12.50%
Cowlitz Project | Salishan-Mohegan, LLC | Cowlitz Tribe | Land
Schedule of Long-term Development Projects [Line Items]
Transfer of property			$ 20,000
Cowlitz Project | Salishan-Mohegan, LLC | CTGA
Schedule of Long-term Development Projects [Line Items]
Reduction in notes payable			$ 342
Cowlitz Project | Salishan-Mohegan, LLC | CTGA | Land
Schedule of Long-term Development Projects [Line Items]
Transfer of property	$ 686
Cowlitz Project | Cowlitz Tribe
Schedule of Long-term Development Projects [Line Items]
Number of authorized gaming machines, operation | gaming_machine						3,000
Number of authorized table games, operation | table_game						75
Number of authorized gaming machines, leasing | gaming_machine						1,075
Number of authorized gaming facilities | table_game						60
Salishan-Mohegan, LLC | Unrelated entity
Schedule of Long-term Development Projects [Line Items]
Membership or limited partnership interest percentage						40.00%
Salishan-Mohegan, LLC | Mohegan Ventures-Northwest, LLC
Schedule of Long-term Development Projects [Line Items]
Membership or limited partnership interest percentage						49.15%
Salishan-Mohegan, LLC | Mohegan Tribe of Indians of Connecticut
Schedule of Long-term Development Projects [Line Items]
Membership or limited partnership interest percentage						10.85%