Note 2: Investments in Securities: Mortgage-backed securities portfolio (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Fixed rates of interest
Mortgage-backed securities	$ 108,500
Variable rates of interest
Mortgage-backed securities	84,000
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC)
Agency mortgage-backed securities	37,200
Federal National Mortgage Association Certificates and Obligations (FNMA)
Agency mortgage-backed securities	92,100
Federal National Mortgage Association Certificates and Obligations (FNMA) | Fixed rates of interest
Mortgage-backed securities	56,300
Government National Mortgage Association Certificates and Obligations (GNMA)
Agency mortgage-backed securities	23,900
Agency collateralized mortgage obligations	$ 39,300