Investments: Narrative (Details)	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2020 USD ($)	Sep. 30, 2024 USD ($) securities	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) securities	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) securities
Investments [Abstract]
Investments held-to-maturity		$ 2,462,000		$ 2,462,000		$ 2,456,000
Payments to acquire marketable securities	$ 2,400,000
Securities in unrealized loss position | securities		108		108		123
Securities in unrealized loss position for 12 months or more | securities		103		103		113
Investments pledged as collateral for FHLB advances		50.00%		50.00%
Investments pledged as collateral for public deposits		$ 29,500,000		$ 29,500,000		$ 26,500,000
Principal repayments on investments available-for-sale			$ 0	40,000,000.0	$ 0
Net gain on sale of investments		0		0
Proceeds from Sale of Debt Securities, Available-for-Sale		$ 0		$ 0