Note 15: Disclosures About Fair Value of Financial Instruments: Schedule Of Financial Instruments Fair Value (Details)	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Unrecognized financial instruments (net of contractual value) | Commitments to Originate Loans
Financial Instruments Owned Carrying Amount	$ 0	$ 0
Financial Instruments, Owned, at Fair Value	$ 0	$ 0
Fair Value Hierarchy Level	3	3
Unrecognized financial instruments (net of contractual value) | Letter of Credit
Financial Instruments Owned Carrying Amount	$ 61	$ 109
Financial Instruments, Owned, at Fair Value	$ 61	$ 109
Fair Value Hierarchy Level	3	3
Unrecognized financial instruments (net of contractual value) | Line of Credit
Financial Instruments Owned Carrying Amount	$ 0	$ 0
Financial Instruments, Owned, at Fair Value	$ 0	$ 0
Fair Value Hierarchy Level	3	3
Financial Assets | Loans Receivable
Financial Instruments Owned Carrying Amount	$ 4,413,764	$ 4,153,982
Financial Instruments, Owned, at Fair Value	$ 4,422,175	$ 4,129,984
Fair Value Hierarchy Level	3	3
Financial Assets | Cash and Cash Equivalents
Financial Instruments Owned Carrying Amount	$ 338,266	$ 220,155
Financial Instruments, Owned, at Fair Value	$ 338,266	$ 220,155
Fair Value Hierarchy Level	1	1
Financial Assets | Mortgage loans held for sale
Financial Instruments Owned Carrying Amount	$ 23,973	$ 9,242
Financial Instruments, Owned, at Fair Value	$ 23,973	$ 9,242
Fair Value Hierarchy Level	2	2
Financial Assets | Interest Receivable
Financial Instruments Owned Carrying Amount	$ 14,139	$ 13,530
Financial Instruments, Owned, at Fair Value	$ 14,139	$ 13,530
Fair Value Hierarchy Level	3	3
Financial Assets | Investment in FHLBank stock and other interest-earning assets
Financial Instruments Owned Carrying Amount	$ 11,036	$ 13,473
Financial Instruments, Owned, at Fair Value	$ 11,036	$ 13,473
Fair Value Hierarchy Level	3	3
Financial Liabilities | Junior Subordinated Debt
Financial Instruments Owned Carrying Amount	$ 25,774	$ 25,774
Financial Instruments, Owned, at Fair Value	$ 25,774	$ 25,774
Fair Value Hierarchy Level	3	3
Financial Liabilities | Subordinated Debt
Financial Instruments Owned Carrying Amount	$ 148,217	$ 74,276
Financial Instruments, Owned, at Fair Value	$ 153,844	$ 76,875
Fair Value Hierarchy Level	2	2
Financial Liabilities | Deposits
Financial Instruments Owned Carrying Amount	$ 4,443,757	$ 3,960,106
Financial Instruments, Owned, at Fair Value	$ 4,454,083	$ 3,963,875
Fair Value Hierarchy Level	3	3
Financial Liabilities | Short-term Debt
Financial Instruments Owned Carrying Amount	$ 156,260	$ 312,324
Financial Instruments, Owned, at Fair Value	$ 156,260	$ 312,324
Fair Value Hierarchy Level	3	3
Financial Liabilities | Interest Payable
Financial Instruments Owned Carrying Amount	$ 2,859	$ 4,250
Financial Instruments, Owned, at Fair Value	$ 2,859	$ 4,250
Fair Value Hierarchy Level	3	3