Financial Statements Schedules Schedule VI. Supplemental Information Concerning Property-Casualty Insurance Operations - USD ($) $ in Thousands	3 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	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Liability for Claims and Claims Adjustment Expense, Property Casualty Liability	$ 63,652				$ 53,795				$ 63,652	$ 53,795	$ 55,471
Net Investment Income									2,669	8,244	2,955
Unearned Premiums	36,686				40,176				36,686	40,176	35,234
Premiums Earned, Net, Property and Casualty	31,447	$ 32,556	$ 33,518	$ 32,922	33,419	$ 32,949	$ 31,813	$ 29,427	130,443	127,608	117,433
Amortization									28,428	27,822	26,361
Supplemental Information for Property, Casualty Insurance Underwriters, Paid Claims and Claims Adjustment Expense									110,427	105,534	93,483
Supplemental Information for Property, Casualty Insurance Underwriters, Premiums Written									126,959	132,550	116,239
Balance at January 1, net	13,045				13,609				13,045	13,609	12,143	$ 12,197
Property, Liability and Casualty Insurance Product Line [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Liability for Claims and Claims Adjustment Expense, Property Casualty Liability	63,652				53,795				63,652	53,795	55,471	$ 63,895
Net Investment Income									1,784
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims Current Year									100,097	96,289	86,439
Unearned Premiums					40,176					40,176	35,234
Premiums Earned, Net, Property and Casualty									130,443	127,608	117,433
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims, Prior Years									20,694	8,095	616
Amortization									24,203	24,154	23,333
Supplemental Information for Property, Casualty Insurance Underwriters, Premiums Written									126,959	132,550	116,239
Balance at January 1, net	6,720				7,782				6,720	7,782	6,696
Corporation [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Net Investment Income										5,530	2,811
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims Current Year									100,097	96,289
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims, Prior Years									20,694	8,095
Amortization									24,203	24,154	23,333
Balance at January 1, net	$ 6,720				$ 7,782				$ 6,720	$ 7,782	$ 6,696