CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN CAPITAL - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Total capital at beginning of period	$ (24,751)	$ 188,727	$ 137,433	$ 270,794
Net income (loss)	(49,929)	19,877	(180,536)	18,301
Foreign currency translation adjustment	6,088	(4,041)	(1,076)	(8,346)
Redemption of membership interest related to the New England Black Wolves franchise				75
Other				44
Total capital at end of period	(77,173)	189,563	$ (77,173)	$ 189,563
Accounting Standards Update [Extensible List]			us-gaap:AccountingStandardsUpdate201602Member	us-gaap:AccountingStandardsUpdate201409Member
Cumulative Effect Period Of Adoption Adjustment
Total capital at beginning of period				$ (41,575)
Cowlitz Project
Redemption of Mohegan Tribe membership interest in the Cowlitz Project				(10,000)
Mohegan Tribe
Distributions	(8,333)	(15,000)	$ (32,333)	(39,000)
Mohegan Tribe | Cowlitz Project
Distributions				(730)
Salishan Company, LLC | Cowlitz Project
Distributions	(248)		(661)
Retained Earnings (Deficit)
Total capital at beginning of period	(17,989)	174,053	137,124	250,707
Net income (loss)	(50,045)	19,839	(180,745)	18,103
Redemption of membership interest related to the New England Black Wolves franchise				(4,499)
Total capital at end of period	(76,615)	178,892	(76,615)	178,892
Retained Earnings (Deficit) | Cumulative Effect Period Of Adoption Adjustment
Total capital at beginning of period				(41,575)
Retained Earnings (Deficit) | Cowlitz Project
Redemption of Mohegan Tribe membership interest in the Cowlitz Project				(4,114)
Retained Earnings (Deficit) | Mohegan Tribe
Distributions	(8,333)	(15,000)	(32,333)	(39,000)
Retained Earnings (Deficit) | Mohegan Tribe | Cowlitz Project
Distributions				(730)
Retained Earnings (Deficit) | Salishan Company, LLC | Cowlitz Project
Distributions	(248)		(661)
Accumulated Other Comprehensive Income (Loss)
Total capital at beginning of period	(13,589)	7,016	(6,633)	11,062
Foreign currency translation adjustment	5,859	(3,810)	(1,097)	(7,900)
Other				44
Total capital at end of period	(7,730)	3,206	(7,730)	3,206
Total Capital Attributable to Mohegan Tribal Gaming Authority
Total capital at beginning of period	(31,578)	181,069	130,491	261,769
Net income (loss)	(50,045)	19,839	(180,745)	18,103
Foreign currency translation adjustment	5,859	(3,810)	(1,097)	(7,900)
Redemption of membership interest related to the New England Black Wolves franchise				(4,499)
Other				44
Total capital at end of period	(84,345)	182,098	(84,345)	182,098
Total Capital Attributable to Mohegan Tribal Gaming Authority | Cumulative Effect Period Of Adoption Adjustment
Total capital at beginning of period				(41,575)
Total Capital Attributable to Mohegan Tribal Gaming Authority | Cowlitz Project
Redemption of Mohegan Tribe membership interest in the Cowlitz Project				(4,114)
Total Capital Attributable to Mohegan Tribal Gaming Authority | Mohegan Tribe
Distributions	(8,333)	(15,000)	(32,333)	(39,000)
Total Capital Attributable to Mohegan Tribal Gaming Authority | Mohegan Tribe | Cowlitz Project
Distributions				(730)
Total Capital Attributable to Mohegan Tribal Gaming Authority | Salishan Company, LLC | Cowlitz Project
Distributions	(248)		(661)
Non-controlling Interests
Total capital at beginning of period	6,827	7,658	6,942	9,025
Net income (loss)	116	38	209	198
Foreign currency translation adjustment	229	(231)	21	(446)
Redemption of membership interest related to the New England Black Wolves franchise				4,574
Total capital at end of period	$ 7,172	$ 7,465	$ 7,172	7,465
Non-controlling Interests | Cowlitz Project
Redemption of Mohegan Tribe membership interest in the Cowlitz Project				$ (5,886)