Represents the total fair value of other than stock (or unit) option plans granted during the reporting period.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of additional shares authorized for issuance under share-based payment arrangement.

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Number of shares authorized for issuance under share-based payment arrangement.

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Percentage of vesting of award under share-based payment arrangement.

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STOCKHOLDERS' EQUITY - Stock Based Compensation (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Based Compensation
Number of shares outstanding			223,802	225,026
Restricted stock
Stock Based Compensation
Number of shares awarded	151,500	149,550
Number of shares forfeited	200
Number of shares vested	129,925	122,125
Number of shares outstanding	723,050	701,675	701,675	674,250
Vesting period	5 years
RSUs
Stock Based Compensation
Number of shares awarded			75,026	77,776	76,250
Number of shares forfeited				5,250
Number of shares outstanding	223,802	225,026
TSR awards
Stock Based Compensation
Percentage of RSUs to vest upon achievement of specified criteria	50.00%
ROC Awards
Stock Based Compensation
Percentage of RSUs to vest upon achievement of specified criteria	50.00%
2019 Incentive Plan
Stock Based Compensation
Maximum number of shares authorized for issuance	750,000
2019 Incentive Plan \| Restricted stock and RSU grants
Stock Based Compensation
Number of shares outstanding	450,952
2019 Incentive Plan \| Restricted stock
Stock Based Compensation
Number of shares outstanding	300,900
2019 Incentive Plan \| RSUs
Stock Based Compensation
Number of shares outstanding	150,052
2016 Incentive Plan
Stock Based Compensation
Additional awards authorized	0
2016 Incentive Plan \| Restricted stock and RSU grants
Stock Based Compensation
Number of shares outstanding	495,900
2016 Incentive Plan \| Restricted stock
Stock Based Compensation
Number of shares outstanding	422,150
2016 Incentive Plan \| RSUs
Stock Based Compensation
Number of shares awarded						76,250
Number of shares forfeited			51,907
Number of shares vested			24,343
Number of shares outstanding	73,750
Pay-for-performance program \| RSUs
Stock Based Compensation
Number of shares forfeited	0
Number of shares vested	0
Vesting period	3 years
Pay-for-performance program \| RSUs \| Awards granted in 2020
Stock Based Compensation
Aggregate fair value of the shares granted	$ 962,000
Pay-for-performance program \| RSUs \| Awards granted in 2019
Stock Based Compensation
Aggregate fair value of the shares granted	1,446,000
Pay-for-performance program \| RSUs \| Awards granted in 2018
Stock Based Compensation
Aggregate fair value of the shares granted	$ 1,006,000