VARIABLE INTEREST ENTITY (Carrying Amount of VIE Consolidated Assets and Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Investments
Debt securities - available-for-sale, at fair value:	$ 424,148	$ 423,238
Equity securities, at fair value	19,535	15,434
Total investments (including $0 and $26,284 related to the VIE, respectively)	448,938	444,021
Cash and cash equivalents	69,457	86,228	$ 81,535	$ 74,593
Reinsurance recoverable	134,736	124,601
Prepaid reinsurance premiums	134,285	135,492
Premiums receivable, net	34,286	46,393
Deferred acquisition costs, net	47,395	40,893
Other assets	14,388	13,403
Total assets	890,611	904,873
Liabilities
Loss and loss adjustment expense reserves	221,114	230,515	$ 461,591	$ 158,110
Unearned premiums	296,329	294,423
Reinsurance payable	77,004	71,944
Debt, net of deferred financing costs	44,377	49,251
Other liabilities	23,938	25,059
Total liabilities	667,675	677,414
Monarch Delaware - Variable Interest Entity
Investments
Debt securities - available-for-sale, at fair value:		25,111
Equity securities, at fair value		1,173
Total investments (including $0 and $26,284 related to the VIE, respectively)	0	26,284
Cash and cash equivalents	0	14,211
Reinsurance recoverable		3,323
Prepaid reinsurance premiums		2,481
Premiums receivable, net	0	1,184
Deferred acquisition costs, net		1,722
Other assets	$ 0	2,322
Total assets		51,527
Liabilities
Loss and loss adjustment expense reserves		6,356
Unearned premiums		8,752
Reinsurance payable		1,802
Debt, net of deferred financing costs		4,930
Other liabilities		1,825
Total liabilities		$ 23,665