Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Available-for-sale Debt securities, Amortized cost	$ 147,193	$ 235,633
Available-for-sale Equity securities, Amortized cost	$ 44,184	$ 54,282
Preferred stock, no par value
Preferred stock, authorized	18,100,000	18,100,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, no par value
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	8,368,188	8,762,416
Common stock, outstanding	8,368,188	8,762,416
7% Series A Cumulative Convertible Preferred Stock [Member]
Preferred stock, no par value
Preferred stock, authorized	1,500,000	1,500,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Series B Preferred Stock [Member]
Preferred stock, no par value
Preferred stock, authorized	400,000	400,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0