Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Other invested assets	$ 1,954	$ 1,972
Federal Deposit Insurance Corporation amount	250
Short-term investment balances in investment that are insured by SIPC	$ 500
Nodak Insurance [Member]
Ownership percentage	100.00%
Battle Creek [Member]
Ownership percentage	100.00%

Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current.

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-Name Accounting Standards Codification
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant