LONG-TERM DEBT - Additional Information (Details) - USD ($)			1 Months Ended				3 Months Ended					6 Months Ended		12 Months Ended
	Apr. 21, 2016	Feb. 10, 2014	Dec. 19, 2018	Jun. 30, 2017	Apr. 18, 2017	Apr. 21, 2016	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 20, 2018	Apr. 17, 2015
Debt Instrument [Line Items]
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.
Letters of Credit Outstanding, Amount							$ 828,000					$ 828,000
Long-term Debt, Gross								$ 350,000,000						$ 350,000,000
Debt Instrument, Interest Rate, Stated Percentage								9.25%						9.25%
Gain Losses on Extinguishment of Debt							0			$ 626,000		0	$ 865,000
Debt Instrument, Interest Rate Terms					The 2017 Credit Facility contains 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 Notes. The 2017 Credit Facility also contains 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.									The 2018 Credit Facility contains 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 also contains 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 and 6.75 to 1.00 in 2022.
Interest Expense, Total							22,003,000			19,155,000		44,154,000	38,436,000
Comcast Note [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 11,900,000					$ 11,900,000
Long-term Debt, Gross								$ 11,900,000						$ 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
Senior Subordinated Notes due February 2020 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross							$ 0	2,000,000				$ 0		2,000,000
Debt Instrument, Interest Rate, Stated Percentage							9.25%					9.25%
Gain Losses on Extinguishment of Debt								2,800,000
Debt Instrument, Repurchase Amount								$ 243,000,000						$ 243,000,000
Debt Instrument, Redemption Price, Percentage								100.88%
Write off of Deferred Debt Issuance Cost								$ 649,000
Premium Paid to the Bondholders								$ 2,100,000
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
MGM National Harbor Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 50,000,000					$ 50,000,000
Long-term Debt, Gross							51,100,000					51,100,000
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
Asset Backed Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Term	5 years
Long-term Debt, Gross							9,000,000					9,000,000
Line of Credit Facility, Maximum Borrowing Capacity	$ 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
Repayments of Long-term Debt, Total			$ 20,000,000				$ 824,000			875,000		$ 1,600,000	1,800,000
Debt, Weighted Average Interest Rate							6.49%	5.82%				6.49%		5.82%
Percentage of Outstanding Principal Amount				0.25%
Long-term Debt, Gross					$ 350,000,000		$ 322,300,000	$ 323,900,000				$ 322,300,000		$ 323,900,000
Debt Instrument, Interest Rate, Stated Percentage					2.00%
Debt Instrument, Description					The 2017 Credit Facility matures 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 2022 Notes. 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 6.49% for 2019 and was 5.82% for 2018.
2018 Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount																$ 192,000,000
Number of Days to Notify the Changes														5 days
Debt Instrument, Interest Rate, Stated Percentage, If 50% of Term Repaid														11.875%
Debt Instrument, Interest Rate, Stated Percentage, If 75% of Term Repaid														10.875%
Excess Cash Flows														75.00%
Percentage of Distributions														100.00%
Repayments of Long-term Debt, Total							3,600,000					14,200,000
Long-term Debt, Gross							177,800,000	$ 192,000,000				177,800,000		$ 192,000,000
Debt Instrument, Interest Rate, Stated Percentage								12.875%						12.875%
Interest Expense, Total							964,000			718,000		1,900,000	1,400,000
Debt Instrument Additional Interest Payment Term On Prepayment														The loans under the 2018 Credit Facility may be voluntarily prepaid prior to February 15, 2020 subject to payment of a prepayment premium. The Company is 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 is also required to use 75% of excess cash flow (as defined in the 2018 Credit Facility, which exclude 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.
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%
Gain Losses on Extinguishment of Debt									$ 120,000	626,000	$ 239,000
Debt Instrument, Repurchase Amount									$ 5,000,000	$ 14,000,000	$ 11,000,000		$ 14,000,000
Debt Instrument, Redemption Price, Percentage									97.25%	95.125%	97.375%