INCOME TAXES - Federal income tax (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Federal income tax expense:
Federal income tax, at statutory rate	$ 3,881	$ 2,078	$ 8,249	$ 3,811
Federal income tax, at statutory rate (as a percent)	21.00%	21.00%	21.00%	21.00%
Increase (decrease) resulting from:
Federally tax exempt interest income	$ (353)	$ (370)	$ (720)	$ (727)
Federally tax exempt interest income (as a percent)	(1.90%)	(3.70%)	(1.80%)	(4.00%)
State taxes, net of federal benefit	$ 1,303	$ 727	$ 2,817	$ 1,358
State taxes, net of federal benefit (as a percent)	7.10%	7.30%	7.20%	7.50%
Other	$ (66)	$ 42	$ (28)	$ 66
Other (as a percent)	(0.40%)	0.40%	(0.10%)	0.30%
Income tax expense	$ 4,765	$ 2,477	$ 10,318	$ 4,508
Total (as a percent)	25.80%	25.00%	26.30%	24.80%