NEW ACCOUNTING STANDARDS - Revenue Disaggregation (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Net revenues	$ 319,500	$ 331,484
Connecticut
Disaggregation of Revenue [Line Items]
Net revenues	252,679
Connecticut | Gaming
Disaggregation of Revenue [Line Items]
Net revenues	170,482
Connecticut | Food and beverage
Disaggregation of Revenue [Line Items]
Net revenues	29,135
Connecticut | Hotel
Disaggregation of Revenue [Line Items]
Net revenues	21,220
Connecticut | Retail, entertainment and other
Disaggregation of Revenue [Line Items]
Net revenues	31,842
Connecticut | Management and development
Disaggregation of Revenue [Line Items]
Net revenues	0
Pennsylvania
Disaggregation of Revenue [Line Items]
Net revenues	60,791
Pennsylvania | Gaming
Disaggregation of Revenue [Line Items]
Net revenues	51,453
Pennsylvania | Food and beverage
Disaggregation of Revenue [Line Items]
Net revenues	5,713
Pennsylvania | Hotel
Disaggregation of Revenue [Line Items]
Net revenues	1,758
Pennsylvania | Retail, entertainment and other
Disaggregation of Revenue [Line Items]
Net revenues	1,867
Pennsylvania | Management and development
Disaggregation of Revenue [Line Items]
Net revenues	0
Other
Disaggregation of Revenue [Line Items]
Net revenues	6,090
Other | Gaming
Disaggregation of Revenue [Line Items]
Net revenues	0
Other | Food and beverage
Disaggregation of Revenue [Line Items]
Net revenues	(42)
Other | Hotel
Disaggregation of Revenue [Line Items]
Net revenues	(1)
Other | Retail, entertainment and other
Disaggregation of Revenue [Line Items]
Net revenues	421
Other | Management and development
Disaggregation of Revenue [Line Items]
Net revenues	$ 5,712