Loans Receivable: Non-performing Loans, Foregone interest, and loans committed (Details) - USD ($)
Dec. 31, 2016
Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net [2],[3] $ 828,161,000 [1] $ 697,416,000 [4]
One-to-four family residential    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 249,435,000 253,772,000
Multifamily    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 123,250,000 [1],[2] 122,747,000 [3],[4]
Commercial Real Estate    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 303,694,000 [1],[2] 244,211,000 [3],[4]
Construction Land Development    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 136,922,000 [1],[2] 62,103,000 [3],[4]
Business    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 7,938,000 [1],[2] 7,604,000 [3],[4]
Consumer    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 6,922,000 [1],[2] 6,979,000 [3],[4]
One-to-four family residential non-owner occupied    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 111,601,000 [1],[2] 106,543,000 [3],[4]
One-to-four family, residential, owner occupied    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 137,834,000 [1],[2] 147,229,000 [3],[4]
Performing Financing Receivable    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net [3] 827,303,000 696,331,000
Performing Financing Receivable | One-to-four family residential    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 248,637,000 252,776,000
Performing Financing Receivable | Multifamily    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 123,250,000 122,747,000
Performing Financing Receivable | Commercial Real Estate    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 303,694,000 244,211,000
Performing Financing Receivable | Construction Land Development    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 136,922,000 62,103,000
Performing Financing Receivable | Business    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 7,938,000 7,604,000
Performing Financing Receivable | Consumer    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 6,862,000 6,890,000
Performing Financing Receivable | One-to-four family residential non-owner occupied    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 111,600,000 106,500,000
Performing Financing Receivable | One-to-four family, residential, owner occupied    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 137,000,000 146,200,000
Nonperforming Financing Receivable    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net [3] 858,000 1,085,000
Nonperforming Financing Receivable | One-to-four family residential    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 798,000 996,000
Nonperforming Financing Receivable | Multifamily    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 0 0
Nonperforming Financing Receivable | Commercial Real Estate    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 0 0
Nonperforming Financing Receivable | Construction Land Development    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 0 0
Nonperforming Financing Receivable | Business    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 0 0
Nonperforming Financing Receivable | Consumer    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 60,000 89,000
Nonperforming Financing Receivable | One-to-four family residential non-owner occupied    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net 0 0
Nonperforming Financing Receivable | One-to-four family, residential, owner occupied    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Net $ 798,000 $ 996,000
[1] (1) There were no loans 90 days past due and still accruing interest at December 31, 2015.
[2] (2) Net of LIP.
[3] Net of LIP.
[4] (1) There were no loans 90 days past due and still accruing interest at December 31, 2016.