LONG-TERM DEBT - Additional Information (Details) - USD ($)								1 Months Ended	3 Months Ended		12 Months Ended
	Nov. 09, 2020	Jan. 17, 2019	Dec. 19, 2018	Apr. 18, 2017	Apr. 21, 2016	Apr. 17, 2015	Feb. 10, 2010	Apr. 21, 2016	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Jun. 25, 2020	Nov. 13, 2019	Apr. 17, 2019	Dec. 20, 2018	Feb. 10, 2014
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage										9.25%
Gain Losses on Extinguishment of Debt									$ 2,900,000		$ (2,894,000)
Debt Instrument, Interest Rate Terms											The 2018 Credit Facility contained customary representations and warranties and events of default, affirmative and negative covenants (in each case, subject to materiality exceptions and qualifications). The 2018 Credit Facility, as amended, also contained certain financial covenants, including a maintenance covenant requiring the Company's total gross leverage ratio to be not greater than 8.0 to 1.00 in 2019, 7.5 to 1.00 in 2020, 7.25 to 1.00 in 2021, 6.75 to 1.00 in 2022 and 6.25 to 1.00 in 2023. As of December 31, 2020, the Company was in compliance with all of its financial covenants under the 2018 Credit Facility.
Interest Expense, Total											$ 74,507,000	$ 81,400,000
Debt Instrument Additional Interest Payment Term On Prepayment				Beginning with the interest payment date occurring in June 2017 and ending in March 2023, the Company was required to repay principal, to the extent then outstanding, equal to 1∕4 of 1% of the aggregate initial principal amount of all term loans incurred on the effective date of the 2017 Credit Facility
Period prior to the earlier to occur of the term loan maturity or stated maturity					30 days
Long-term Debt, Maturity Date										Dec. 31, 2022
Repayments of Long Term Debt, Excess Cash Flow Payments											$ 11,100,000
Amortization of debt premium									$ 3,500,000
Comcast Note [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount															$ 11,900,000
Long-term Debt, Gross										$ 11,900,000
Debt Instrument, Interest Rate, Stated Percentage									10.47%		10.47%
Senior Secured Notes Due 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross						$ 350,000,000
Debt Instrument, Description						an original issue price of 100.0% plus accrued interest
9.25% Senior Subordinated Notes due February 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage										100.88%
Debt Instrument, Redemption Period, Start Date											Feb. 15, 2019
Amount redeemable										$ 243,000,000
9.25% Senior Subordinated Notes due February 2020 [Member] | Private Offering [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross																	$ 335,000,000
Debt Instrument, Periodic Payment							$ 15,500,000
Senior Subordinated Notes due April 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Description						The 7.375% Notes were offered at an original issue price of 100.0% plus accrued interest from April 17, 2015, and matured on April 15, 2022.
MGM National Harbor Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount													$ 3,600,000			$ 50,000,000
Long-term Debt, Gross									$ 57,900,000		$ 57,900,000	$ 52,100,000
Debt Instrument, Interest Rate, Stated Percentage									7.00%		7.00%
Debt Instrument, Unamortized Discount (Premium), Net									$ 1,000,000		$ 1,000,000
Long Term Debt Percentage Paid In Kind											4.00%
Debt Issuance Costs, Net									1,700,000		$ 1,700,000
7.375% Notes
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 347,000,000
Percentage of exchange offer	99.15%
8.75% Senior Secured Notes due December 2022
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	8.75%
Debt Instrument, Redemption Price, Percentage											100.00%
Amount redeemable									15,000,000		$ 15,000,000
ABL Facility
Debt Instrument [Line Items]
Debt Instrument, Face Amount														$ 37,500,000
Letters of Credit									871,000		871,000			7,500,000
Line of Credit Facility, Maximum Borrowing Capacity					$ 25,000,000			$ 25,000,000						$ 25,000,000
Percentage Borrowing Of Eligible Accounts								(85.00%)
2017 Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount									350,000,000		350,000,000
Covenant Compliance Description For Maintaining Interest Coverage Ratio												maintaining an interest coverage ratio of no less than:1.25 to 1.00 on June 30, 2017 and the last day of each fiscal quarter thereafter.
Covenant Compliance Description For Maintaining Total Leverage Ratio												)  maintaining a senior leverage ratio of no greater than:5.85 to 1.00 on June 30, 2017 and the last day of each fiscal quarter thereafter.
Repayments of Long-term Debt, Total			$ 20,000,000									$ 3,300,000
Long-term Debt, Gross				$ 350,000,000					317,300,000		317,300,000
Debt Instrument, Description				Until its termination as described in Note 16 - Subsequent Events, the 2017 Credit Facility matured on the earlier of (i) April 18, 2023, or (ii) in the event such debt is not repaid or refinanced, 91 days prior to the maturity of the Company's 7.375% Notes (as defined below). At the Company's election, the interest rate on borrowings under the 2017 Credit Facility are based on either (i) the then applicable base rate (as defined in the 2017 Credit Facility) as, for any day, a rate per annum (rounded upward, if necessary, to the next 1/100th of 1%) equal to the greater of (a) the prime rate published in the Wall Street Journal, (b) 1/2 of 1% in excess rate of the overnight Federal Funds Rate at any given time, (c) the one-month LIBOR rate commencing on such day plus 1.00%) and (d) 2%, or (ii) the then applicable LIBOR rate (as defined in the 2017 Credit Facility). The average interest rate was approximately 5.17% for 2020 and was 6.27% for 2019.The 2017 Credit Facility was s (i) guaranteed by each entity that guarantees the Company's 7.375% Notes on a pari passu basis with the guarantees of the 7.375% Notes and (ii) secured on a pari passu basis with the Company's 7.375% Notes. The Company's obligations under the 2017 Credit Facility were secured, subject to permitted liens and except for certain excluded assets (i) on a first priority basis by certain notes priority collateral, and (ii) on a second priority basis by collateral for the Company's asset-backed line of credit.
Debt Instrument, Interest Rate Terms				The 2017 Credit Facility contained customary representations and warranties and events of default, affirmative and negative covenants (in each case, subject to materiality exceptions and qualifications) which may be more restrictive than those governing the 7.375% Notes. The 2017 Credit Facility also contained certain financial covenants, including a maintenance covenant requiring the Company's interest expense coverage ratio (defined as the ratio of consolidated EBITDA to consolidated interest expense) to be greater than or equal to 1.25 to 1.00 and its total senior secured leverage ratio (defined as the ratio of consolidated net senior secured indebtedness to consolidated EBITDA) to be less than or equal to 5.85 to 1.00.
2018 Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount									10,000,000		10,000,000					$ 192,000,000
Long-term Debt, Gross									129,900,000		$ 129,900,000	167,100,000
Debt Instrument, Description											The 2018 Credit Facility was scheduled to mature on December 31, 2022 (the "Maturity Date"). In connection with the Exchange Offer (as defined below), we also entered into an amendment to certain terms of our 2018 Credit Facility including the extension of the maturity date to March 31, 2023. Interest rates on borrowings under the 2018 Credit Facility were either (i) from the Funding Date to the Maturity Date, 12.875% per annum, (ii) 11.875% per annum, once 50% of the term loan borrowings had been repaid or (iii) 10.875% per annum, once 75% of the term loan borrowings had been repaid. Interest payments began on the last day of the 3-month period commencing on the Funding Date. Within 90 days following the completion of the Exchange Offer (as defined below), the Company was required to repay $10 million of the 2018 Credit Facility. The amendment was accounted for as a modification in accordance with the provisions of ASC 470, "Debt".
Debt Instrument, Interest Rate Terms											Until its termination as described in Note 16 - Subsequent Events, borrowings under the 2018 Credit Facility were subject to customary conditions precedent, as well as a requirement under the 2018 Credit Facility that (i) the Company's total gross leverage ratio on a pro forma basis be not greater than 8:00 to 1:00 (this total gross leverage ratio test steps down as described below), (ii) neither of the administrative agents under the Company's existing credit facilities nor the trustee under the Company's existing senior secured notes due 2022 have objected to the terms of the new credit documents and (iii) certification by the Company that the terms and conditions of the 2018 Credit Facility satisfied the requirements of the definition of "Permitted Refinancing" (as defined in the agreements governing the Company's existing credit facilities) and neither of the administrative agents under the Company's existing credit facilities notified the Company within five (5) business days prior to funding the borrowings under the 2018 Credit Facility that it disagreed with such determination (including a reasonable description of the basis upon which it disagrees).
Interest Expense, Total											$ 4,500,000	$ 3,900,000
Debt Instrument Additional Interest Payment Term On Prepayment											The term loans could be voluntarily prepaid prior to February 15, 2020 subject to payment of a prepayment premium. The Company was required to repay principal to the extent then outstanding on each quarterly interest payment date, commencing on the last business day in March 2019, equal to one quarter of 7.5% of the aggregate initial principal amount of all term loans incurred on the Funding Date to December 2019, commencing on the last business day in March 2020, one quarter of 10.0% of the aggregate initial principal amount of all term loans incurred on the Funding Date to December 2021, and, commencing on the last business day in March 2021, one quarter of 12.5% of the aggregate initial principal amount of all term loans incurred on the Funding Date to December 2022. The Company was also required to use 75% of excess cash flow ("ECF payment") as defined in the 2018 Credit Facility, which excluded any distributions to the Company or its restricted subsidiaries in respect of its interests in the MGM National Harbor, to repay outstanding term loans at par, paid semiannually and to use 100% of all distributions to the Company or its restricted subsidiaries received in respect of its interest in the MGM National Harbor to repay outstanding terms loans at par. During the year ended December 31, 2020, the Company repaid approximately $37.2 million under the 2018 Credit Facility. Included in the repayments made during the year ended December 31, 2020 was approximately $11.1 million in ECF payments in accordance with the agreement. During the year ended December 31, 2019, the Company repaid approximately $24.9 million, under the 2018 Credit Facility. Included in the repayments made during the year ended December 31, 2019 was approximately $3.5 million in ECF payments in accordance with the agreement.
Debt Instrument, Unamortized Discount (Premium), Net									3,800,000		$ 3,800,000
2018 Credit Facility [Member] | Debt Financing Cost [Member]
Debt Instrument [Line Items]
Debt Issuance Costs, Net									$ 875,000		$ 875,000
Senior Subordinated Notes Due From 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage						7.375%											100.00%
Debt Instrument, Redemption Price, Percentage		100.00%