Fair Value: Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments available-for-sale	$ 140,868	$ 132,242
FHLB stock	7,410	9,882
Derivative fair value asset	2,454	1,526
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash on hand and in banks	7,167	9,189
Interest-earning deposits with banks	19,094	6,942
Investments available-for-sale	0	0
Loans receivable, net	0	0
FHLB stock	0	0
Accrued interest receivable	0	0
Derivative fair value asset	0	0
Deposits	440,265	430,750
Certificates of deposit, retail	0	0
Certificates of deposit, brokered	0	0
Advances from the FHLB	0	0
Accrued interest payable	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash on hand and in banks	0	0
Interest-earning deposits with banks	0	0
Investments available-for-sale	140,868	132,242
Loans receivable, net	0	0
FHLB stock	7,410	9,882
Accrued interest receivable	4,664	4,084
Derivative fair value asset	2,454	1,526
Deposits	0	0
Certificates of deposit, retail	370,948	331,199
Certificates of deposit, brokered	101,812	74,947
Advances from the FHLB	145,108	214,477
Accrued interest payable	541	326
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash on hand and in banks	0	0
Interest-earning deposits with banks	0	0
Investments available-for-sale	0	0
Loans receivable, net	977,320	980,578
FHLB stock	0	0
Accrued interest receivable	0	0
Derivative fair value asset	0	0
Deposits	0	0
Certificates of deposit, retail	0	0
Certificates of deposit, brokered	0	0
Advances from the FHLB	0	0
Accrued interest payable	0	0
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash on hand and in banks	7,167	9,189
Interest-earning deposits with banks	19,094	6,942
Investments available-for-sale	140,868	132,242
Loans receivable, net	995,557	988,662
FHLB stock	7,410	9,882
Accrued interest receivable	4,664	4,084
Derivative fair value asset	2,454	1,526
Deposits	440,265	430,750
Certificates of deposit, retail	373,931	333,264
Certificates of deposit, brokered	102,083	75,488
Advances from the FHLB	149,000	216,000
Accrued interest payable	541	326
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash on hand and in banks	7,167	9,189
Interest-earning deposits with banks	19,094	6,942
Investments available-for-sale	140,868	132,242
Loans receivable, net	977,320	980,578
FHLB stock	7,410	9,882
Accrued interest receivable	4,664	4,084
Derivative fair value asset	2,454	1,526
Deposits	440,265	430,750
Certificates of deposit, retail	370,948	331,199
Certificates of deposit, brokered	101,812	74,947
Advances from the FHLB	145,108	214,477
Accrued interest payable	$ 541	$ 326