Long-Term Debt - Schedule of Long-term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Long-term debt	$ 2,043,161	$ 1,909,157
Less: current portion of long-term debt	(73,251)	(76,909)
Long-term debt, net of current portion	1,969,910	1,832,248
Line of Credit | Senior Secured Credit Facility - Revolving
Debt Instrument [Line Items]
Long-term debt	247,000	102,000
Line of Credit | Senior Secured Credit Facility - Term Loan A
Debt Instrument [Line Items]
Long-term debt	245,473	263,829
Line of Credit | Senior Secured Credit Facility - Term Loan B
Debt Instrument [Line Items]
Long-term debt	802,957	805,394
Line of Credit | 2016 7 7/8% Senior Unsecured Notes
Debt Instrument [Line Items]
Long-term debt	491,216	490,435
Line of Credit | MGE Niagara Resorts Credit Facility - Revolving
Debt Instrument [Line Items]
Long-term debt	24,696	0
Line of Credit | MGE Niagara Resorts Credit Facility - Term Loan
Debt Instrument [Line Items]
Long-term debt	67,080	73,564
Line of Credit | Mohegan Expo Credit Facility
Debt Instrument [Line Items]
Long-term debt	28,301	29,357
Line of Credit | Guaranteed Credit Facility
Debt Instrument [Line Items]
Long-term debt	30,686	31,840
Convertible Debenture | MGE Niagara Resorts Convertible Debenture
Debt Instrument [Line Items]
Long-term debt	28,224	30,204
Notes Payable to Banks | Redemption Note Payable
Debt Instrument [Line Items]
Long-term debt	76,425	81,329
Senior Unsecured Notes | Other
Debt Instrument [Line Items]
Long-term debt	$ 1,103	$ 1,205