QUARTERLY RESULTS OF OPERATIONS - (Summary of Unaudited Quarterly Results of Operations) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2017	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Selected Quarterly Financial Information [Abstract]
Net premiums earned	$ 87,503	$ 80,764	$ 83,554	$ 81,660	$ 76,922	$ 69,405	$ 60,045	$ 54,997	$ 165,214	$ 245,978	$ 333,481	$ 261,369	$ 213,020
Total Revenue	101,752	98,697	98,159	93,054	89,971	81,758	70,786	65,010	191,213	289,910	391,662	307,525	243,471
Losses and loss adjustment expenses	58,874	75,367	56,417	56,899	71,594	45,973	48,983	31,260			72,405	60,404	19,119
Total costs and expenses	92,185	108,876	92,504	89,170	103,948	78,914	71,090	51,770	181,674	290,550	382,735	305,722	180,526
Net (loss) income attributable to Federated National Holding Company shareholders	$ 6,296	$ (4,724)	$ 3,995	$ 2,422	$ (8,793)	$ 2,099	$ (405)	$ 8,114	$ 6,417	$ 1,693	$ 7,989	$ 1,015	$ 39,301
Net income (loss) per share - basic (in dollars per share)	$ 0.48	$ (0.36)	$ 0.30	$ 0.18	$ (0.65)	$ 0.15	$ (0.03)	$ 0.59	$ 0.48	$ 0.13	$ 0.61	$ 0.07	$ 2.86
As Reported [Member]
Selected Quarterly Financial Information [Abstract]
Net premiums earned		$ 78,663	$ 83,159	$ 78,493	$ 75,425	$ 69,405	$ 60,045	$ 54,997	$ 161,652	$ 240,315		$ 259,872	$ 210,020
Total Revenue		95,892	97,563	92,923	88,570	83,790	75,064	68,960	188,281	284,173		316,384	249,893
Losses and loss adjustment expenses		72,935	54,956	50,831	67,158	43,613	47,025	29,545
Total costs and expenses		107,300	90,311	87,813	104,590	82,250	73,249	53,562	175,919	283,219		313,651	184,700
Net (loss) income attributable to Federated National Holding Company shareholders		$ (5,511)	$ 4,945	$ 3,145	$ (12,116)	$ 1,394	$ 991	$ 9,535	$ 8,090	$ 2,579		$ (196)	$ 40,885
Net income (loss) per share - basic (in dollars per share)		$ (0.42)	$ 0.38	$ 0.23	$ (0.89)	$ 0.10	$ 0.07	$ 0.69	$ 0.61	$ 0.20		$ (0.01)	$ 2.98