ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details)			3 Months Ended		6 Months Ended		12 Months Ended
	Nov. 09, 2020 USD ($)	Jan. 01, 2019	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) segment	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Jun. 01, 2021 USD ($)	Jan. 24, 2021 USD ($)	Jun. 25, 2020 USD ($)	Nov. 13, 2019 USD ($)	Dec. 31, 2018	Dec. 20, 2018 USD ($)	Apr. 18, 2017 USD ($)	Nov. 30, 2016 USD ($)	Apr. 10, 2015 USD ($)
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Number of reportable segments | segment					4
Carrying value of debt			$ 832,505,000		$ 832,505,000		$ 855,156,000
Accumulated deficit			(787,046,000)		(787,046,000)		(804,919,000)
Revenue from Contract with Customer, Including Assessed Tax			107,593,000	$ 76,008,000	199,033,000	$ 170,883,000
Reassessed Estimated Fair Value of Award			27,100,000		27,100,000		25,600,000
Selling, General and Administrative Expense, Total			31,510,000	22,294,000	61,497,000	51,757,000
Related Party Transaction, Due from (to) Related Party, Total							244,000
Due to Related Parties			4,000		4,000		6,000
Operating Income (Loss)			37,920,000	20,382,000	61,677,000	(6,905,000)
Goodwill			223,402,000		223,402,000		223,402,000
Operating Expenses, Total			69,673,000	55,626,000	137,356,000	177,788,000
Unearned Event Income			6,118,000	10,352,000	6,118,000	10,352,000	5,921,000
Selling, General and Administrative Expense, Total			31,510,000	22,294,000	61,497,000	51,757,000
Impairment of Long-Lived Assets Held-for-use			0	0	0	53,650,000
Operating Lease, Right-of-Use Asset			42,202,000		42,202,000		40,918,000
Operating Lease, Liability			45,925,000		45,925,000
Retained Earnings (Accumulated Deficit), Total			(787,046,000)		(787,046,000)		$ (804,919,000)
INTEREST EXPENSE			15,853,000	18,395,000	33,898,000	37,533,000
Accounting Standards Update 2016-02
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Lease, Practical Expedients, Package [true false]		true
Reach Media
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Due to Related Parties			460,000		460,000
Barter Transactions [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Revenue from Contract with Customer, Including Assessed Tax			440,000	527,000	889,000	1,000,000.0
Cost of Goods and Services Sold			302,000	384,000	614,000	755,000
Selling, General and Administrative Expense, Total			138,000	143,000	275,000	286,000
Selling, General and Administrative Expense, Total			138,000	143,000	275,000	286,000
Radio broadcasting and Reach Media segments [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Sales Commissions and Fees			4,100,000	2,500,000	7,600,000	7,200,000
Fantastic Voyage [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Operating Income Guarantee					1,750,000
Digital Segment [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Goodwill			7,222,000		$ 7,222,000
Launch support asset
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Finite Lived Intangible Assets Weighted Average Amortization Period					7 years 4 months 24 days		7 years 4 months 24 days
Finite Lived Intangible Assets Remaining Weighted Average Amortization Period					4 years		4 years 6 months
Selling, General and Administrative Expense, Total			229,000	151,000
Amortization of Intangible Assets			105,000	105,000	$ 211,000	211,000
Operating Expenses, Total					457,000	302,000
Selling, General and Administrative Expense, Total			$ 229,000	151,000
Atlanta market and Indianapolis
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Impairment of Long-Lived Assets Held-for-use					5,900,000
Atlanta, Cincinnati, Dallas, Houston, Indianapolis, Philadelphia, Raleigh, Richmond and St. Louis market radio broadcasting licenses
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Impairment of Long-Lived Assets Held-for-use					47,700,000
Tom Joyner Foundation Inc [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Reimbursement Expenditure Guarantee					$ 1,000,000.0
Percentage of Performance Bonus					50.00%
Tom Joyner Foundation Inc [Member] | Fantastic Voyage [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Operating Income Guarantee					$ 250,000
Chief Executive Officer [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Percentage Of Award Amount			4.00%		4.00%
2028 Notes
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Long-term Debt, Gross			$ 825,000,000.0		$ 825,000,000.0
Fair value of debt			$ 888,900,000		$ 888,900,000
Debt Instrument, Interest Rate, Stated Percentage			7.375%		7.375%
Face amount of debt									$ 825,000,000
MGM National Harbor Loan [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Long-term Debt, Gross							$ 57,900,000
Fair value of debt							64,800,000
Carrying value of debt			$ 0		$ 0		57,889,000
Debt Instrument, Interest Rate, Stated Percentage			7.00%		7.00%
Face amount of debt			$ 50,000,000.0		$ 50,000,000.0								$ 50,000,000.0
Other Income			1,900,000	80,000	3,600,000	1,600,000
ABL Facility [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Long-term Debt, Gross			$ 0		$ 0		0
7.375% Senior Secured Notes Are Due In April 2022 [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Long-term Debt, Gross	$ 347,000,000.0						3,000,000.0
Fair value of debt							2,800,000
Percentage of exchange offer	99.15%
Debt Instrument, Interest Rate, Stated Percentage	7.375%		7.375%		7.375%
8.75% Senior Secured Notes due December 2022
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Long-term Debt, Gross							347,000,000.0
Fair value of debt							338,000,000.0
Carrying value of debt			$ 0		$ 0		$ 347,016,000
Debt Instrument, Interest Rate, Stated Percentage	8.75%		8.75%		8.75%		8.75%
PPP loan
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Fair value of debt			$ 7,500,000		$ 7,500,000
Carrying value of debt			7,505,000		7,505,000		$ 0
Face amount of debt								$ 7,500,000
Tv One Llc [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Sales Commissions and Fees			$ 4,400,000	3,200,000	$ 8,200,000	6,900,000
Reach Media Inc [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent			80.00%		80.00%
Customer Advances [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Unearned Event Income			$ 0	0	$ 0	0
Unearned Income [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Revenue from Contract with Customer, Including Assessed Tax			545,000	448,000	2,600,000	2,100,000
2017 Credit Facility [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Long-term Debt, Gross														$ 350,000,000
Carrying value of debt			$ 0		$ 0		317,332,000
Debt Instrument, Interest Rate, Stated Percentage			8.75%		8.75%
Face amount of debt			$ 350,000,000.0		$ 350,000,000.0
2017 Credit Facility [Member] | Senior Secured Credit Facility [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Long-term Debt, Gross							317,300,000
Fair value of debt							293,500,000
Face amount of debt														$ 350,000,000.0
2018 Credit Facility [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Long-term Debt, Gross							129,900,000
Fair value of debt							132,500,000
Carrying value of debt			0		0		$ 129,935,000
Debt Instrument, Interest Rate, Stated Percentage												9.25%
Face amount of debt			10,000,000		10,000,000					$ 3,600,000			$ 192,000,000.0
ABL Facility
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Face amount of debt											$ 37,500,000
Employment Agreement Award [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Selling, General and Administrative Expense, Total			911,000	98,000	1,500,000	1,300,000
Selling, General and Administrative Expense, Total			$ 911,000	$ 98,000	$ 1,500,000	$ 1,300,000
MGM National Harbor [Member]
ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES [Line Items]
Investment Owned, at Cost															$ 35,000,000	$ 5,000,000