INCOME TAXES - Effective income tax rate reconciliation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
INCOME TAXES
Tax at statutory rate	21.00%	21.00%	21.00%	21.00%
Nontaxable interest and dividends	(0.50%)	(0.60%)	(0.50%)	(0.50%)
Tax credits	(2.80%)	(1.70%)	(2.50%)	(1.70%)
State taxes	2.50%	1.60%	1.90%	1.70%
Other	1.30%	0.20%	0.90%
Effective income tax rate reconciliation, percent, Total	21.50%	20.50%	20.80%	20.50%
Tax obligation under tax examinations				$ 4.0