Regulatory Matters: Narrative (Details) - Timberland Bank	Sep. 30, 2023	Sep. 30, 2022
Compliance with Regulatory Capital Requirements for Mortgage Companies [Line Items]
Tier 1 Risk-based Capital Ratio, Regulatory Minimum To Be Adequately Capitalized, Ratio	4.50%	4.50%
Tier 1 Risk-based Capital, Regulatory Minimum To Be Adequately Capitalized, Ratio	0.060	0.060
Total Capital, Regulatory Minimum To Be Adequately Capitalized, Ratio	0.080	0.080
Tier 1 Leverage Capital, Regulatory Minimum To Be Adequately Capitalized, Ratio	0.040	0.040