Benefit Plans Multiemployer Pension Plans (Details) - USD ($)						12 Months Ended
	Nov. 23, 2016	Oct. 07, 2016	Nov. 25, 2015	Nov. 28, 2014	Sep. 25, 2014	Dec. 31, 2016		Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Multiemployer Plans [Line Items]
First Financial Northwest’s Plan(1)						103.70%	[1]	102.80%
Deferred compensation expense						$ 36,000		$ 101,000		$ 170,000
Pentegra DB Plan
Multiemployer Plans [Line Items]
Contributions by employer	$ 499,871,000	$ 40,129,000	$ 540,000,000	$ 539,932,000	$ 8,735,000	$ 540,000,000		$ 540,000,000		$ 548,667,000
Multiemployer Plans, Pension | Pentegra DB Plan
Multiemployer Plans [Line Items]
Assumptions used calculating net periodic benefit cost						6.09%		6.28%
Maximum contribution rate						5.00%
Total contributions made to plan									$ 163,100,000		$ 190,800,000

[1] Market value of plan assets reflects any contributions received through June 30, 2016, or 2015, respectively.