NEW ACCOUNTING STANDARDS - Revenue Disaggregation (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 1,388,810	$ 1,388,810	$ 1,355,632	$ 1,380,003
Connecticut
Disaggregation of Revenue [Line Items]
Revenues		992,043
Pennsylvania
Disaggregation of Revenue [Line Items]
Revenues		251,054
Canada
Disaggregation of Revenue [Line Items]
Revenues		112,525
Other
Disaggregation of Revenue [Line Items]
Revenues		33,428
Gaming | Connecticut
Disaggregation of Revenue [Line Items]
Revenues		654,273
Gaming | Pennsylvania
Disaggregation of Revenue [Line Items]
Revenues		211,800
Gaming | Canada
Disaggregation of Revenue [Line Items]
Revenues		70,339
Gaming | Other
Disaggregation of Revenue [Line Items]
Revenues		0
Food and beverage | Connecticut
Disaggregation of Revenue [Line Items]
Revenues		114,446
Food and beverage | Pennsylvania
Disaggregation of Revenue [Line Items]
Revenues		22,981
Food and beverage | Canada
Disaggregation of Revenue [Line Items]
Revenues		20,319
Food and beverage | Other
Disaggregation of Revenue [Line Items]
Revenues		(202)
Hotel | Connecticut
Disaggregation of Revenue [Line Items]
Revenues		84,543
Hotel | Pennsylvania
Disaggregation of Revenue [Line Items]
Revenues		8,246
Hotel | Canada
Disaggregation of Revenue [Line Items]
Revenues		4,451
Hotel | Other
Disaggregation of Revenue [Line Items]
Revenues		(5)
Retail, entertainment and other | Connecticut
Disaggregation of Revenue [Line Items]
Revenues		138,781
Retail, entertainment and other | Pennsylvania
Disaggregation of Revenue [Line Items]
Revenues		8,027
Retail, entertainment and other | Canada
Disaggregation of Revenue [Line Items]
Revenues		17,416
Retail, entertainment and other | Other
Disaggregation of Revenue [Line Items]
Revenues		1,206
Management, development and other | Connecticut
Disaggregation of Revenue [Line Items]
Revenues		0
Management, development and other | Pennsylvania
Disaggregation of Revenue [Line Items]
Revenues		0
Management, development and other | Canada
Disaggregation of Revenue [Line Items]
Revenues		0
Management, development and other | Other
Disaggregation of Revenue [Line Items]
Revenues		$ 32,429