Loans Receivable Loans Receivable: Average Recorded Investment and Interest Income Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	$ 18,003	$ 26,975	$ 34,410
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	808	1,588	1,738
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	6,105	10,400	14,751
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	341	399	731
Impaired Financing Receivable, Average Recorded Investment	24,108	37,375	49,161
Impaired Financing Receivable, Interest Income, Accrual Method	1,149	1,987	2,469
One-to-four family, residential, owner occupied
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	1,773	2,566	3,180
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	93	156	110
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	1,301	2,026	2,131
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	32	104	89
Impaired Financing Receivable, Average Recorded Investment	3,074	4,592	5,311
Impaired Financing Receivable, Interest Income, Accrual Method	125	260	199
One-to-four family residential non-owner occupied
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	12,438	20,653	25,350
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	553	1,061	1,409
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	3,680	5,520	7,801
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	170	236	415
Impaired Financing Receivable, Average Recorded Investment	16,118	26,173	33,151
Impaired Financing Receivable, Interest Income, Accrual Method	723	1,297	1,824
Multifamily
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	1,227	1,344	1,575
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	74	106	30
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0	236	1,430
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	0	0	77
Impaired Financing Receivable, Average Recorded Investment	1,227	1,580	3,005
Impaired Financing Receivable, Interest Income, Accrual Method	74	106	107
Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	2,467	2,295	4,180
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	80	253	187
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	1,025	2,192	2,817
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	139	42	129
Impaired Financing Receivable, Average Recorded Investment	3,492	4,487	6,997
Impaired Financing Receivable, Interest Income, Accrual Method	219	295	316
Construction Land Development
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	99	396	495
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	0	17	18
Impaired Financing Receivable, Average Recorded Investment	99	396	495
Impaired Financing Receivable, Interest Income, Accrual Method	0	17	18
Consumer
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	98	117	125
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	8	12	2
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0	30	77
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	0	0	3
Impaired Financing Receivable, Average Recorded Investment	98	147	202
Impaired Financing Receivable, Interest Income, Accrual Method	$ 8	$ 12	$ 5