INCOME TAXES - Income Tax Reconciliation (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Statutory federal income tax rate applied to pre-tax income	21.00%	35.00%	21.00%	35.00%
State income taxes	1.20%	0.50%	1.20%	0.60%
Investment income not subject to tax	(1.80%)	(5.40%)	(2.60%)	(3.80%)
Uncertain tax positions	0.00%	(2.00%)	0.00%	(0.30%)
Change in State Tax Rate	0.00%	0.00%	(0.50%)	0.00%
Prior period adjustments	0.00%	(2.60%)	0.00%	(0.80%)
Other	(0.90%)	0.00%	(0.30%)	(0.10%)
Effective tax rate (as a percent)	19.50%	25.50%	18.80%	30.60%