Investments Fixed Maturities by Contractual Maturity Periods (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Due In One Year or Less, Amortized Cost	$ 14,733
Due In One Year or Less, Fair Value	14,674
Due After One Year Through Five Years, Amortized Cost	29,824
Due After One Year Through Five Years, Fair Value	29,179
Due After Five Year Through Ten Years, Amortized Cost	2,194
Due After Five Year Through Ten Years, Fair Value	2,126
Due After Ten Years, Amortized Cost	4,652
Due After Ten Years, Fair Value	4,520
Fixed maturities, cost	51,403	$ 53,746
Estimated Fair Value, Fixed Maturities	$ 50,499	$ 53,214