Loans Loans (Analysis of Troubled Debt Restructurings) (Details) loan in Millions	12 Months Ended
Dec. 31, 2017 USD ($) Modifications contract	Dec. 31, 2016 USD ($) loan Modifications contract	Dec. 31, 2015 USD ($) Modifications contract
Financing Receivable, Modifications [Line Items]
Financing Receivable Modifications Additional Commitment To Lend	$ 506,000	$ 508,000
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0	$ 0
FHLB Advances, Collateral Pledged	$ 1,443,554,000	$ 1,510,514,000
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing, Number of Loans \| loan		0.0
Loans, Excluding Purchased Credit Impaired Loans [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Modifications	60	54	7
Pre-Modification Outstanding Recorded Investment	$ 18,122,000	$ 7,679,000	$ 3,808,000
Post-Modification Outstanding Recorded Investment	$ 18,122,000	$ 7,677,000	$ 3,790,000
Loans, Excluding Purchased Credit Impaired Loans [Member] \| Commercial business: Secured loans [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Modifications	10	9	5
Pre-Modification Outstanding Recorded Investment	$ 5,655,000	$ 2,131,000	$ 3,724,000
Post-Modification Outstanding Recorded Investment	$ 5,655,000	$ 2,131,000	$ 3,706,000
Loans, Excluding Purchased Credit Impaired Loans [Member] \| Commercial business: Unsecured loans [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Modifications	1	0	0
Pre-Modification Outstanding Recorded Investment	$ 26,000	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	$ 26,000	$ 0	$ 0
Loans, Excluding Purchased Credit Impaired Loans [Member] \| Real estate: One-to-four family residential [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Modifications	3	3	1
Pre-Modification Outstanding Recorded Investment	$ 583,000	$ 203,000	$ 30,000
Post-Modification Outstanding Recorded Investment	$ 583,000	$ 203,000	$ 30,000
Loans, Excluding Purchased Credit Impaired Loans [Member] \| Real estate: Commercial and multifamily residential: Commercial land [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Modifications	1	0	0
Pre-Modification Outstanding Recorded Investment	$ 687,000	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	$ 687,000	$ 0	$ 0
Loans, Excluding Purchased Credit Impaired Loans [Member] \| Real estate: Commercial and multifamiIy residential: Income property [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Modifications	1	0	0
Pre-Modification Outstanding Recorded Investment	$ 1,152,000	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	$ 1,152,000	$ 0	$ 0
Loans, Excluding Purchased Credit Impaired Loans [Member] \| Real estate: Commercial and multifamiIy residential: Owner occupied [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Modifications	1	1	0
Pre-Modification Outstanding Recorded Investment	$ 78,000	$ 250,000	$ 0
Post-Modification Outstanding Recorded Investment	$ 78,000	$ 250,000	$ 0
Loans, Excluding Purchased Credit Impaired Loans [Member] \| Real estate construction: Commercial and multifamily residential: Owner occupied [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Modifications	1	0	0
Pre-Modification Outstanding Recorded Investment	$ 4,050,000	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	$ 4,050,000	$ 0	$ 0
Loans, Excluding Purchased Credit Impaired Loans [Member] \| Consumer [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Modifications	42	41	1
Pre-Modification Outstanding Recorded Investment	$ 5,891,000	$ 5,095,000	$ 54,000
Post-Modification Outstanding Recorded Investment	$ 5,891,000	$ 5,093,000	$ 54,000

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Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing, Number of Loans

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- Definition

Amount of the collateral pledged in support of federal home loan bank advances outstanding.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
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