INCOME TAXES (Reconciliation of statutory federal income tax rate) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
INCOME TAXES
Pretax income at statutory, amount									$ 9,253	$ 7,723
Pretax income at statutory rates									21.00%	21.00%
State and local taxes, net of federal income tax benefit, amount									$ 4,385,000	$ 3,260,000
State and local taxes, net of federal income tax benefit, rate									9.95%	8.87%
Nondeductible expenses, amount									$ 430,000	$ 327,000
Nondeductible expenses, rate									0.97%	0.89%
Excess tax deduction on equity awards, amount									$ (132,000)	$ (83,000)
Excess tax deduction on equity awards, rate									(0.30%)	(0.23%)
Tax-exempt income, net amount									$ (2,000)	$ (6,000)
Tax-exempt income, net rate									0.00%	(0.02%)
Other, amount									$ (7,000)
Other, rate									(0.01%)
Effective income tax expense, amount	$ 3,699,000	$ 3,571,000	$ 2,880,000	$ 3,777,000	$ 2,418,000	$ 3,348,000	$ 2,634,000	$ 2,822,000	$ 13,927,000	$ 11,221,000
Effective income tax expense, rate									31.61%	30.51%