Investments: Narrative (Details)	1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 31, 2020 USD ($)	Jun. 30, 2023 USD ($) securities	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) securities	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) securities
Debt Securities, Available-for-sale [Line Items]
Securities in unrealized loss position | securities		127		127		123
Securities in unrealized loss position for 12 months or more | securities		103		103		62
Investments pledged as collateral for FHLB advances		50.00%		50.00%
Investments pledged as collateral for public deposits		$ 26,700,000		$ 26,700,000		$ 21,000,000
Gain on sale of investments available-for-sale			$ 0		$ 0
Proceeds from calls and maturities of investments available-for-sale		0		0	3,382,000
Payments to acquire marketable securities	$ 2,400,000			0	68,264,000
Investments held-to-maturity		2,444,000		2,444,000		2,444,000
Principal repayments on investments available-for-sale			$ 1,000,000		$ 3,400,000
Fair value of securities		206,770,000		206,770,000		207,998,000
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Fair value of securities		$ 26,809,000		$ 26,809,000		$ 30,480,000