Investments (Major Categories of Investment Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Investment income	$ 19,966	$ 17,034	$ 14,842
Investment expenses	(1,092)	(692)	(873)
Investment income (loss), net of expenses	18,874	16,342	13,969
U.S. Treasury securities and obligations of U.S. Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment income	566	594	670
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment income	7,839	5,573	1,435
Collateralized Corporate Bank Loans [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment income	4,302	3,190	4,727
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment income	4,633	5,442	5,901
Collateralized Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment income	1,049	1,320	1,288
Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment income	706	277	148
Parent Company [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment income (loss), net of expenses	210	70	120
Equity Securities [Member] | Equity Securities All Others [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment income	$ 871	$ 638	$ 673