SEGMENT REPORTING (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2017 USD ($) segment	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)
Segment Reporting [Abstract]
Number of reportable segments (in segment) | segment	2
Segment Reporting Information [Line Items]
Net revenues	$ 1,380,003	$ 1,334,794	$ 1,291,620
Income (loss) from operations	257,235	261,143	233,175
Accretion of discount to the redemption liability	(3,840)	0	0
Accretion of discount to the relinquishment liability	0	0	(227)
Interest income	13,732	9,560	7,983
Interest expense, net of capitalized interest	(114,319)	(136,194)	(143,876)
Loss on modification and early extinguishment of debt	(74,888)	(484)	(3,987)
Loss from unconsolidated affiliates	(1,509)	(939)	(972)
Other income (expense), net	6	(9)	43
Net income	76,417	133,077	92,139
(Income) loss attributable to non-controlling interests	(972)	(427)	2,255
Net income attributable to Mohegan Tribal Gaming Authority	75,445	132,650	94,394
Comprehensive income:
Foreign currency translation adjustment	(8,446)	10,495	0
Other comprehensive income (loss)	(8,446)	10,495	0
Other comprehensive (income) loss attributable to non-controlling interests	4,465	(5,389)	0
Other comprehensive income (loss) attributable to Mohegan Tribal Gaming Authority	(3,981)	5,106	0
Comprehensive income attributable to Mohegan Tribal Gaming Authority	71,464	137,756	94,394
Capital expenditures incurred	101,533	48,962	30,024
Total assets	2,235,681	2,227,962
Operating Segments | Mohegan Sun
Segment Reporting Information [Line Items]
Net revenues	1,079,920	1,022,076	994,010
Income (loss) from operations	249,403	237,605	212,211
Comprehensive income:
Capital expenditures incurred	57,033	39,921	24,521
Total assets	1,333,012	1,332,231
Operating Segments | Mohegan Sun Pocono
Segment Reporting Information [Line Items]
Net revenues	278,938	298,677	295,135
Income (loss) from operations	33,145	41,445	45,817
Comprehensive income:
Capital expenditures incurred	6,897	7,575	5,448
Total assets	582,241	551,116
Operating Segments | Corporate and other
Segment Reporting Information [Line Items]
Net revenues	21,385	19,133	7,567
Income (loss) from operations	(25,313)	(17,907)	(24,853)
Comprehensive income:
Capital expenditures incurred	37,603	1,466	55
Total assets	320,428	344,615
Inter-segment revenues
Segment Reporting Information [Line Items]
Net revenues	$ (240)	$ (5,092)	$ (5,092)