SCHEDULE III - SUPPLEMENTARY INSURANCE INFORMATION (Details) - Property/Casualty Insurance [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplementary Insurance Information [Abstract]
Deferred policy acquisition costs		$ 8,496	$ 6,568	$ 5,608
Reserves for unpaid claims and claim adjustment expenses		988,305	865,339	680,274
Unearned premiums		74,810	71,625	53,085
Other policy claims and benefits payable		0	0	0
Net premium earned		447,288	432,880	328,145
Net investment income	[1]	26,249	22,048	18,095
Benefits, claims, losses and settlement expenses	[1]	348,468	345,864	247,518
Amortization of deferred policy acquisition costs		81,734	78,105	70,574
Other operating expenses	[1],[2]	34,043	23,514	14,043
Net premiums written		$ 452,242	$ 444,398	$ 353,389

[1] Allocations of certain expenses have been made to investment income, settlement expenses and other operating expenses and are based on a number of assumptions and estimates. Results among these categories would change if different methods were applied.

[2] Commission allowances relating to reinsurance ceded are offset against other operating expenses.