LONG-TERM DEBT (Details) $ in Thousands				9 Months Ended
	Nov. 11, 2020 USD ($)	Nov. 10, 2020 USD ($)	Nov. 14, 2019 USD ($) Facility	Sep. 30, 2021 USD ($) School	Oct. 29, 2021 USD ($)	Dec. 31, 2020 USD ($)
Long-term debt [Abstract]
Deferred financing fees				$ (485)		$ (621)
Long term debt				15,848		17,212
Less current maturities				(2,000)		(2,000)
Long-term debt, excluding current maturities				13,848		15,212
Lender's origination fee				485		621
Letters of credit outstanding				4,000		4,000
Scheduled maturities of long-term debt [Abstract]
2021 (excluding the nine months ended September 30, 2021)				500
2022				2,000
2023				2,000
2024				11,833
Long term debt				16,333		17,800
Term Loan [Member] | Subsequent Event [Member]
Long-term debt [Abstract]
Repayment of term loan and swap termination fee					$ 16,500
Credit Agreement [Member]
Long-term debt [Abstract]
Credit agreement				16,333		$ 17,833
Minimum quarterly average aggregate balances to be maintained				5,000
Bank fees if minimum quarterly average aggregate balances is not maintained				$ 12,500
Limit on payment of cash dividends	$ 2,300	$ 1,700
Term to extend delayed draw availability period				1 year
Period of consideration for payment of cash dividend				24 months
Credit Agreement [Member] | Series A Preferred Stock [Member]
Long-term debt [Abstract]
Limit on payment of cash dividends	$ 2,300	$ 1,700
Period of consideration for payment of cash dividend				24 months
Credit Facility [Member]
Long-term debt [Abstract]
Line of credit facility, maximum borrowing capacity			$ 60,000
Number of facilities available in 2019 credit agreement | Facility			4
Number of schools in states covered under first priority lien | School				3
Credit Facility [Member] | Letter of Credit [Member]
Long-term debt [Abstract]
Percentage of letter of credit fee, quarterly installment			0.25%
Credit Facility [Member] | Term Loan [Member]
Long-term debt [Abstract]
Deferred financing fees			$ (300)
Line of credit facility, maximum borrowing capacity			20,000	$ 0
Expiration date of credit facility				Dec. 01, 2024
Line of credit facility, amortization schedule based period for interest and principal payments				120 months
Net proceeds from term loan			19,700
Lender's origination fee			$ 300
Percentage of swap transaction of principal balance			100.00%
Credit Facility [Member] | Term Loan [Member] | LIBOR [Member]
Long-term debt [Abstract]
Term of variable rate				1 month
Interest rate on credit facility			3.50%
Credit Facility [Member] | Term Loan [Member] | LIBOR [Member] | Interest Rate Floor [Member]
Long-term debt [Abstract]
Interest rate on credit facility			0.25%
Credit Facility [Member] | Delayed Draw Term Loan [Member]
Long-term debt [Abstract]
Line of credit facility, maximum borrowing capacity			$ 10,000	$ 0
Expiration date of credit facility				Dec. 01, 2024
Line of credit facility, amortization schedule based period for interest and principal payments				120 months
Line of credit facility, monthly interest payment period				18 months
Percentage of swap transaction of principal balance			100.00%
Credit Facility [Member] | Delayed Draw Term Loan [Member] | LIBOR [Member]
Long-term debt [Abstract]
Term of variable rate				1 month
Interest rate on credit facility			3.50%
Credit Facility [Member] | Delayed Draw Term Loan [Member] | LIBOR [Member] | Interest Rate Floor [Member]
Long-term debt [Abstract]
Interest rate on credit facility			0.25%
Credit Facility [Member] | Credit Agreement [Member]
Long-term debt [Abstract]
Line of credit facility, maximum borrowing capacity			$ 15,000
Expiration date of credit facility				Jan. 31, 2021
Credit Facility [Member] | Revolving Loan [Member]
Long-term debt [Abstract]
Line of credit facility, maximum borrowing capacity			$ 15,000
Expiration date of credit facility				Nov. 13, 2022
Line of credit facility, frequency of principal and interest periodic payment				monthly
Loan repayment period				30 days
Credit Facility [Member] | Revolving Loan [Member] | Interest Rate Floor [Member]
Long-term debt [Abstract]
Interest rate on credit facility			4.00%
Credit Facility [Member] | Revolving Loan [Member] | LIBOR [Member] | Interest Rate Floor [Member]
Long-term debt [Abstract]
Interest rate on credit facility			0.00%
Credit Facility [Member] | Revolving Loan [Member] | Prime Rate [Member]
Long-term debt [Abstract]
Interest rate on credit facility			0.50%
Credit Facility [Member] | Revolving Loan [Member] | Letter of Credit [Member]
Long-term debt [Abstract]
Line of credit facility, maximum borrowing capacity			$ 10,000
Letters of credit outstanding			$ 4,000