STOCKHOLDERS' EQUITY - Additional Information (Details)								3 Months Ended			6 Months Ended		12 Months Ended
	Jul. 06, 2022 USD ($) $ / shares shares	Jul. 05, 2022 USD ($) director shares	Oct. 29, 2021 shares	Jul. 06, 2021 USD ($) director shares	Jun. 23, 2021 shares	Jan. 19, 2021 USD ($) shares	Jun. 12, 2019 shares	Jun. 30, 2022 USD ($) $ / shares shares	Jun. 30, 2021 USD ($) $ / shares shares	Mar. 31, 2021 USD ($) shares	Jun. 30, 2022 USD ($) $ / shares shares	Jun. 30, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares	Mar. 07, 2022 USD ($)	Dec. 31, 2021 $ / shares shares	May 17, 2021 USD ($) $ / shares	Jan. 27, 2021 USD ($)	Aug. 18, 2020 USD ($) $ / shares	May 21, 2019 shares	Jun. 02, 2015 shares	Dec. 31, 2009 shares
STOCKHOLDERS' EQUITY
Number of shares issued during period | $												$ 33,282,000
Net proceeds after associated fees and expenses | $											$ 0	33,282,000
Stock Repurchased During Period, Value | $											$ 24,669,000	$ 905,000
Stock options to purchase common stock												20,000
Number of options vested in period								0	0		16,795	832,847
Share-based Compensation, Total | $								$ 336,000	$ 172,000		$ 460,000	$ 425,000
Share-based Compensation Arrangement by Share-based Payment Award Options exercised Number of Shares								60,240	197,256		60,240	197,256
Restricted stock awards [Member]
STOCKHOLDERS' EQUITY
Employee Service Share-based Compensation, Non-vested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition											5 months
Other than options, granted								54,759	62,373		54,759	62,373
Total unrecognized compensation, other than options | $								$ 45,000			$ 45,000
Stock options
STOCKHOLDERS' EQUITY
Stock options to purchase common stock								6,887			6,887
Number of Options, Vested and expected to vest								3,717,000			3,717,000
Employee [Member]
STOCKHOLDERS' EQUITY
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares											$ 1.46
Employee Service Share-based Compensation, Non-vested Awards, Total Compensation Cost Not yet Recognized, Stock Options | $								$ 3,000			$ 3,000
Employee [Member] | Maximum
STOCKHOLDERS' EQUITY
Employee Service Share-based Compensation, Non-vested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition											1 month
Class A And Class D Common Stock [Member]
STOCKHOLDERS' EQUITY
Stock repurchase , Authorized amount | $														$ 25,000,000
Stock repurchase , Authorized amount remaining | $								439,000,000,000			$ 439,000,000,000
Common Class D [Member]
STOCKHOLDERS' EQUITY
Common stock, par value (in dollars per share) | $ / shares																$ 0.001
Stock Repurchased During Period, Shares											4,665,589
Stock Repurchased During Period, Value | $								$ 24,600,000			$ 24,600,000
Repurchase Of Common Stock Price Per Share | $ / shares								$ 5.26			$ 5.26
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized																				8,250,000
Common Class D [Member] | Subsequent events
STOCKHOLDERS' EQUITY
Stock Repurchased During Period, Shares	100,803
Stock Repurchased During Period, Value | $	$ 439,000
Repurchase Of Common Stock Price Per Share | $ / shares	$ 4.30
Common Class D [Member] | Open Market Sale Agreement [Member]
STOCKHOLDERS' EQUITY
Shares issued and sold											0
Common Class D [Member] | Scenario, Plan [Member] | Open Market Sale Agreement [Member] | Maximum
STOCKHOLDERS' EQUITY
Aggregate offering price | $																$ 25,000,000.0
Common Class D [Member] | Employees Stock Option [Member]
STOCKHOLDERS' EQUITY
Stock options to purchase common stock							94,150
Other than options, granted							211,838
Common Class D [Member] | Stock Plan 2009 [Member]
STOCKHOLDERS' EQUITY
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized																					8,250,000
Common Class D [Member] | Stock Vest Tax Repurchase [Member]
STOCKHOLDERS' EQUITY
Stock Repurchased During Period, Shares								16,181	14,051		18,830	509,347
Stock Repurchased During Period, Value | $								$ 91,000	$ 33,000		$ 101,000	$ 904,000
Repurchase Of Common Stock Price Per Share | $ / shares								$ 5.64	$ 2.36		$ 5.36	$ 1.78
Common Class D [Member] | 2019 Equity and Performance Incentive Plan
STOCKHOLDERS' EQUITY
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant								5,836,380			5,836,380								5,500,000
Additional shares authorized					5,519,575
Common Class D [Member] | Chief Financial Officer [Member] | Restricted stock awards [Member] | Share-based Compensation Award, Tranche Two [Member]
STOCKHOLDERS' EQUITY
Stock options to purchase common stock							316,406
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures							711,914
Common Class D [Member] | Chief Financial Officer [Member] | Employees Stock Option [Member] | Share-based Compensation Award, Tranche One [Member]
STOCKHOLDERS' EQUITY
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures							243,750
Common Class D [Member] | Chief Financial Officer [Member] | Employees Stock Option [Member] | Share-based Compensation Award, Tranche Two [Member]
STOCKHOLDERS' EQUITY
Stock options to purchase common stock							108,333
Common Class D [Member] | Four Non-Executive Directors [Member] | Restricted stock awards [Member]
STOCKHOLDERS' EQUITY
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				50.00%
Stock issued during period, value, restricted stock award fair value | $				$ 50,000
Number of non-executive directors, received awards | director				4
Vesting period				2 years
Restricted stock issued				9,671
Common Class D [Member] | Four Non-Executive Directors [Member] | Restricted stock awards [Member] | Subsequent events
STOCKHOLDERS' EQUITY
Stock issued during period, value, restricted stock award fair value | $		$ 50,000
Number of non-executive directors, received awards | director		4
Vesting period		2 years
Restricted stock issued		11,848
Common Class D [Member] | Cathy Hughes [Member] | Employees Stock Option [Member] | Share-based Compensation Award, Tranche One [Member]
STOCKHOLDERS' EQUITY
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures							427,148
Common Class D [Member] | Cathy Hughes [Member] | Employees Stock Option [Member] | Share-based Compensation Award, Tranche Two [Member]
STOCKHOLDERS' EQUITY
Stock options to purchase shares							189,843
Class A Common Stock [Member]
STOCKHOLDERS' EQUITY
Stock Repurchased During Period, Shares								0	0			0
Shares converted			883,890
Class A Common Stock [Member] | Current ATM Program
STOCKHOLDERS' EQUITY
Common stock, par value (in dollars per share) | $ / shares																		$ 0.001
Aggregate offering price | $																	$ 25,000,000.0	$ 25,000,000
Number of shares issued during period | $									$ 21,200,000				$ 2,859,276
Volume weighted average price | $ / shares													$ 5.39
Net proceeds after associated fees and expenses | $						$ 24,000,000.0				$ 2,800,000			$ 14,700,000
Shares issued and sold						4,325,102			1,893,126	420,439
Number of additional shares issued and sold						1,465,826
Gross proceeds | $						$ 25,000,000.0			$ 22,000,000.0	$ 3,000,000.0
Class A Common Stock [Member] | 2019 Equity and Performance Incentive Plan
STOCKHOLDERS' EQUITY
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant								2,000,000			2,000,000
Additional shares authorized					2,000,000
Common Stock Class B
STOCKHOLDERS' EQUITY
Common stock, par value (in dollars per share) | $ / shares								$ 0.001			$ 0.001				$ 0.001
Common stock, shares issued								2,861,843			2,861,843				2,861,843
Common Stock Class C
STOCKHOLDERS' EQUITY
Common stock, par value (in dollars per share) | $ / shares								$ 0.001			$ 0.001				$ 0.001
Shares converted			883,890
Common stock, shares issued								2,045,016			2,045,016				2,045,016