SEGMENT REPORTING (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($)	Sep. 30, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	4
Revenues:
Total	$ 399,052	$ 319,500
Income Statement [Abstract]
Income (loss) from operations	43,425	43,370
Capital [Abstract]
Capital expenditures incurred	36,357	13,049
ASSETS
Total assets	2,855,524		$ 2,511,596
Operating segments | Mohegan Sun
Revenues:
Net revenues:	243,335	252,679
Income Statement [Abstract]
Income (loss) from operations	45,065	44,063
Capital [Abstract]
Capital expenditures incurred	4,631	5,123
ASSETS
Total assets	1,355,934		1,282,384
Operating segments | Mohegan Sun Pocono
Revenues:
Net revenues:	61,954	60,791
Income Statement [Abstract]
Income (loss) from operations	7,794	7,192
Capital [Abstract]
Capital expenditures incurred	999	377
ASSETS
Total assets	545,220		548,424
Operating segments | MGE Niagara Resorts
Revenues:
Net revenues:	84,974	0
Income Statement [Abstract]
Income (loss) from operations	(1,333)	0
Capital [Abstract]
Capital expenditures incurred	7,851	0
ASSETS
Total assets	575,771		342,821
Operating segments | Management, development and other
Revenues:
Net revenues:	9,012	5,712
Income Statement [Abstract]
Income (loss) from operations	(918)	(413)
Capital [Abstract]
Capital expenditures incurred	22,868	7,542
ASSETS
Total assets	358,366		313,458
Corporate
Revenues:
Net revenues:	108	378
Income Statement [Abstract]
Income (loss) from operations	(7,164)	(7,472)
Capital [Abstract]
Capital expenditures incurred	8	7
ASSETS
Total assets	915,650		912,712
Inter-segment
Revenues:
Net revenues:	(331)	(60)
Income Statement [Abstract]
Income (loss) from operations	(19)	$ 0
ASSETS
Total assets	$ (895,417)		$ (888,203)