Long-Term Debt - Schedule of Long-term Debt Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Nov. 04, 2021	Sep. 30, 2021
Debt Schedule [Abstract]
Long-term debt, face value	$ 2,478,300
Less: current portion of long-term debt, face value	(44,012)
Long-term debt, net of current portion, face value	2,434,288
Fair value	2,297,568
Long-term debt, book value	2,304,220		$ 1,938,754
Less: current portion of long-term debt, book value	(44,012)		(80,276)
Long-term debt, net of current portion, book value	2,260,208		1,858,478
Unamortized discounts and debt issuance costs	174,080		34,022
Senior Secured Credit Facility | Line of Credit
Debt Schedule [Abstract]
Long-term debt, face value	0
Long-term debt, book value	0		27,000
Line of Credit | Line of Credit
Debt Schedule [Abstract]
Long-term debt, face value	0
Long-term debt, book value	$ 0		20,227
2021 8% Senior Secured Notes | Senior Notes
Debt Schedule [Abstract]
Stated interest rate (as a percent)	8.00%
Long-term debt, face value	$ 1,175,000
Long-term debt, book value	1,160,271		1,157,731
2016 7 7/8% Senior Unsecured Notes | Senior Notes
Debt Schedule [Abstract]
Long-term debt, face value	500,000
Long-term debt, book value	$ 495,033		493,599
2016 7 7/8% Senior Unsecured Notes | Other
Debt Schedule [Abstract]
Stated interest rate (as a percent)	7.875%
MGE Niagara Credit Facility - Revolving | Line of Credit
Debt Schedule [Abstract]
Long-term debt, face value	$ 0
Long-term debt, book value	0		27,534
MGE Niagara Credit Facility - Swingline | Line of Credit
Debt Schedule [Abstract]
Long-term debt, face value	14,372
Long-term debt, book value	14,372		4,333
MGE Niagara Credit Facility - Term Loan | Line of Credit
Debt Schedule [Abstract]
Long-term debt, face value	65,926
Long-term debt, book value	65,322		68,965
MGE Niagara Convertible Debenture | Convertible Debenture
Debt Schedule [Abstract]
Long-term debt, face value	31,024
Long-term debt, book value	31,024		31,468
Inspire Korea Credit Facility | Line of Credit
Debt Schedule [Abstract]
Long-term debt, face value	321,272
Long-term debt, book value	267,961		0
MGE Korea Term Loan
Debt Schedule [Abstract]
Stated interest rate (as a percent)		17.00%
MGE Korea Term Loan | Line of Credit
Debt Schedule [Abstract]
Long-term debt, face value	298,872
Long-term debt, book value	203,467		0
Mohegan Expo Credit Facility | Line of Credit
Debt Schedule [Abstract]
Long-term debt, face value	0
Long-term debt, book value	0		25,697
Guaranteed Credit Facility | Line of Credit
Debt Schedule [Abstract]
Long-term debt, face value	25,812
Long-term debt, book value	25,459		27,208
Redemption Note Payable | Redemption Note Payable
Debt Schedule [Abstract]
Long-term debt, face value	44,620
Long-term debt, book value	39,909		53,130
Other | Other
Debt Schedule [Abstract]
Long-term debt, face value	1,402
Long-term debt, book value	$ 1,402		$ 1,862