Benefit Plans Multiemployer Pension Plans (Details) - USD ($)			12 Months Ended
	Nov. 28, 2022	Nov. 18, 2021	Dec. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Jun. 30, 2020	Jan. 31, 2020
Multiemployer Plans [Line Items]
Minimum service requisite period			1 year
Vesting period			5 years
First Financial Northwest’s Plan			101.90%	111.20%
Deferred compensation expense			$ 177,000	$ 175,000
Recorded liability			1,000,000.0
Benefit obligation							$ 2,400,000
Pentegra DB Plan
Multiemployer Plans [Line Items]
Contributions by employer	$ 92,000	$ 207,000	$ 92,000	$ 207,000
Multiemployer Plans, Pension | Pentegra DB Plan
Multiemployer Plans [Line Items]
Assumptions used calculating net periodic benefit cost			5.39%	5.56%
Contribution amount					$ 248,600,000	$ 253,200,000
Maximum contribution rate					5.00%