Policy Liabilities and Short Duration Contracts Short Term Insurance Contracts Adjustment Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Claims Development [Line Items]
Liabilities for unpaid claims and claim adjustment expenses, net of reinsurance	$ 573	$ 543
Total reinsurance recoverable on unpaid claims	261	340
Insurance lines other than short duration	7,776	8,655
Total gross liability for unpaid claims and claim adjustment expenses	8,610	9,538	$ 9,653	$ 9,560
Special property [Member]
Claims Development [Line Items]
Liabilities for unpaid claims and claim adjustment expenses, net of reinsurance	501	500
Total reinsurance recoverable on unpaid claims	0	0
Other Insurance Product [Member]
Claims Development [Line Items]
Liabilities for unpaid claims and claim adjustment expenses, net of reinsurance	72	43
Total reinsurance recoverable on unpaid claims	$ 261	$ 340