Investments: Schedule of Available for sale Securities, Debt Maturities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investments [Abstract]
Due within one year, Amortized Cost	$ 4,491
Due after one year through five years, Amortized Cost	2,197
Due after five years through ten years, Amortized Cost	24,447
Due after ten years, Amortized Cost	57,460
Debt maturities, Amortized Cost	88,595
Mortgage-backed investments, Amortized Cost	56,983
Amortized Cost	145,578	$ 133,475
Due within one year, Fair Value	4,491
Due after one year through five years, Fair Value	2,189
Due after five years through ten years, Fair Value	24,151
Due after ten years, Fair Value	57,078
Debt maturities, Fair Value	87,909
Mortgage-backed investments, Fair Value	54,963
Fair Value	$ 142,872