Investments, Aggregated by Industry (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Investments aggregated by industry [Abstract]
Carrying value	$ 217,999	$ 210,670
Cost or amortized cost	215,241	210,505
Carrying value	252,137	244,177
Cost or amortized cost	238,715	235,208
Unrealized gains (losses)	13,422	8,969
U.S. Treasury Securities and Obligations of U.S. Government Agencies and Authorities [Member]
Investments aggregated by industry [Abstract]
Carrying value	32,426	31,102
Cost or amortized cost	32,651	31,458
Unrealized gains (losses)	(225)	(356)
Obligations of States and Political Subdivisions [Member]
Investments aggregated by industry [Abstract]
Carrying value	17,882	17,572
Cost or amortized cost	17,240	17,255
Unrealized gains (losses)	642	317
Utilities and Telecom [Member]
Investments aggregated by industry [Abstract]
Carrying value	21,947	19,635
Cost or amortized cost	19,867	17,624
Unrealized gains (losses)	2,080	2,011
Financial Services [Member]
Investments aggregated by industry [Abstract]
Carrying value	57,506	62,684
Cost or amortized cost	54,960	61,141
Unrealized gains (losses)	2,546	1,543
Other Business - Diversified [Member]
Investments aggregated by industry [Abstract]
Carrying value	41,614	57,663
Cost or amortized cost	41,944	58,732
Unrealized gains (losses)	(330)	(1,069)
Other Consumer - Diversified [Member]
Investments aggregated by industry [Abstract]
Carrying value	68,206	42,271
Cost or amortized cost	59,497	35,748
Unrealized gains (losses)	8,709	6,523
Other Investment [Member]
Investments aggregated by industry [Abstract]
Carrying value	12,556	13,250
Cost or amortized cost	12,556	13,250
Unrealized gains (losses)	$ 0	$ 0