CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN CAPITAL (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Total capital at beginning of period	$ 145,961	$ 229,901	$ 137,433	$ 270,794
Net income (loss)	(140,031)	(12,284)	(130,607)	(1,576)
Foreign currency translation adjustment	(18,581)	(6,204)	(7,164)	(4,305)
Redemption of Mohegan Tribe membership interest in the Cowlitz Project		(10,000)		(10,000)
Redemption of membership interest related to the New England BlackWolves franchise				75
Other		44		44
Total capital at end of period	(24,751)	188,727	$ (24,751)	$ 188,727
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)
Mohegan Tribe
Distributions	(12,000)	(12,000)	$ (24,000)	(24,000)
Mohegan Tribe | Cowlitz Project
Distributions		(730)		(730)
Salishan Company, LLC | Cowlitz Project
Distributions	(100)		(413)
Retained Earnings (Deficit)
Total capital at beginning of period	134,205	203,255	137,124	250,707
Net income (loss)	(140,094)	(12,358)	(130,700)	(1,736)
Redemption of Mohegan Tribe membership interest in the Cowlitz Project		(4,114)		(4,114)
Redemption of membership interest related to the New England BlackWolves franchise				(4,499)
Total capital at end of period	(17,989)	174,053	(17,989)	174,053
Retained Earnings (Deficit) | Cumulative Effect Period Of Adoption Adjustment
Total capital at beginning of period				(41,575)
Retained Earnings (Deficit) | Mohegan Tribe
Distributions	(12,000)	(12,000)	(24,000)	(24,000)
Retained Earnings (Deficit) | Mohegan Tribe | Cowlitz Project
Distributions		(730)		(730)
Retained Earnings (Deficit) | Salishan Company, LLC | Cowlitz Project
Distributions	(100)		(413)
Accumulated Other Comprehensive Income (Loss)
Total capital at beginning of period	4,253	12,866	(6,633)	11,062
Foreign currency translation adjustment	(17,842)	(5,894)	(6,956)	(4,090)
Other		44		44
Total capital at end of period	(13,589)	7,016	(13,589)	7,016
Total Capital Attributable to Mohegan Tribal Gaming Authority
Total capital at beginning of period	138,458	216,121	130,491	261,769
Net income (loss)	(140,094)	(12,358)	(130,700)	(1,736)
Foreign currency translation adjustment	(17,842)	(5,894)	(6,956)	(4,090)
Redemption of Mohegan Tribe membership interest in the Cowlitz Project		(4,114)		(4,114)
Redemption of membership interest related to the New England BlackWolves franchise				(4,499)
Other		44		44
Total capital at end of period	(31,578)	181,069	(31,578)	181,069
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 | Mohegan Tribe
Distributions	(12,000)	(12,000)	(24,000)	(24,000)
Total Capital Attributable to Mohegan Tribal Gaming Authority | Mohegan Tribe | Cowlitz Project
Distributions		(730)		(730)
Total Capital Attributable to Mohegan Tribal Gaming Authority | Salishan Company, LLC | Cowlitz Project
Distributions	(100)		(413)
Non-controlling Interests
Total capital at beginning of period	7,503	13,780	6,942	9,025
Net income (loss)	63	74	93	160
Foreign currency translation adjustment	(739)	(310)	(208)	(215)
Redemption of Mohegan Tribe membership interest in the Cowlitz Project		(5,886)		(5,886)
Redemption of membership interest related to the New England BlackWolves franchise				4,574
Total capital at end of period	$ 6,827	$ 7,658	$ 6,827	$ 7,658