Loans and Credit Quality - Performing and Nonaccrual (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accrual	$ 5,036,194	$ 4,514,586
Nonaccrual	9,638	15,041
Total loans held for investment	5,045,832	4,529,627
Fair value of loans held for investment	4,089	5,477
Recurring [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Fair value of loans held for investment	4,089	5,477
Level 3 [Member] \| Recurring [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Fair value of loans held for investment	4,089	5,477
Consumer loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accrual	1,951,104	1,822,360
Nonaccrual	7,996	12,495
Total loans held for investment	1,959,100	1,834,855
Consumer loans [Member] \| Single family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accrual	1,411,304	1,370,275
Nonaccrual	6,836	11,091
Total loans held for investment	1,418,140	1,381,366
Consumer loans [Member] \| Home equity and other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accrual	539,800	452,085
Nonaccrual	1,160	1,404
Total loans held for investment	540,960	453,489
Commercial real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accrual	2,351,082	2,038,070
Nonaccrual	74	380
Total loans held for investment	2,351,156	2,038,450
Commercial real estate loans [Member] \| Non-owner occupied commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accrual	667,429	622,782
Nonaccrual	0	0
Total loans held for investment	667,429	622,782
Commercial real estate loans [Member] \| Multifamily [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accrual	893,105	727,735
Nonaccrual	0	302
Total loans held for investment	893,105	728,037
Commercial real estate loans [Member] \| Construction/land development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accrual	790,548	687,553
Nonaccrual	74	78
Total loans held for investment	790,622	687,631
Commercial and industrial loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accrual	734,008	654,156
Nonaccrual	1,568	2,166
Total loans held for investment	735,576	656,322
Commercial and industrial loans [Member] \| Owner occupied commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accrual	420,340	390,973
Nonaccrual	384	640
Total loans held for investment	420,724	391,613
Commercial and industrial loans [Member] \| Commercial business [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accrual	313,668	263,183
Nonaccrual	1,184	1,526
Total loans held for investment	$ 314,852	$ 264,709

Financing receivable that is considered to be performing and are still accruing interest.

No definition available.

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- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Amount, before allowance and fees, of loans and leases receivable. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

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- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2196772

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