Investments, Roll-forward of Financial Instruments Measured at Fair Value (Details) - Fixed Maturities [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Assets measured at fair value on a recurring basis [Abstract]
Balance, beginning of period	$ 1,264	$ 2,237
Total realized gains included in earnings		57
Total unrealized losses included in other comprehensive income	105	(30)
Settlements		(1,000)
Balance, end of period	$ 1,369	$ 1,264