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Fair Value of Assets and Liabilities - Fair Value of Financial Instruments (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($) debenture	Dec. 31, 2015 USD ($)
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Investment securities held to maturity	$ 47,867	$ 71,054
Subordinated debenture
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Subordinated debentures	$ 4,950
Subordinated Debt [Abstract]
Number of subordinated debentures acquired | debenture	2
NorCal Community Bancorp Trust I | Subordinated debenture
Subordinated Debt [Abstract]
Basis spread on subordinated debentures	3.05%
NorCal Community Bancorp Trust II | Subordinated debenture
Subordinated Debt [Abstract]
Basis spread on subordinated debentures	1.40%
Carrying Value | Fair Value Hierarchy, Level 1
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and cash equivalents	$ 96,930	26,343
Carrying Value | Fair Value Hierarchy, Level 2
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Investment securities held to maturity	46,423	69,637
Interest receivable	5,645	6,643
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Deposits	1,801,469	1,728,226
Federal Home Loan Bank borrowings	0	67,000
Interest payable	138	187
Carrying Value | Fair Value Hierarchy, Level 3
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Loans, net	1,451,950	1,436,229
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Subordinated debentures	5,540	5,395
Fair Value | Fair Value Hierarchy, Level 1
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and cash equivalents	96,930	26,343
Fair Value | Fair Value Hierarchy, Level 2
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Investment securities held to maturity	47,867	71,054
Interest receivable	5,645	6,643
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Deposits	1,801,932	1,728,717
Federal Home Loan Bank borrowings	0	67,279
Interest payable	138	187
Fair Value | Fair Value Hierarchy, Level 3
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Loans, net	1,471,861	1,470,380
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Subordinated debentures	$ 5,156	$ 5,132

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- Definition

Business Combinations, Number of Debt Instruments Acquired

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No definition available.

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This element represents the disclosures for fair value estimates for financial instruments required in the footnote disclosures to the financial statements. Carrying amount reprsents accrued interest payable on all forms of debt, including deposit liabilities, that has been incurred and is unpaid for time value of money. The carrying value may approximate fair value due to the short-term nature of their settlement dates.

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- Definition

This element represents the disclosures for fair value estimates for financial instruments required in the footnote disclosures to the financial statements. Carrying amount represents interest earned but not received from loan borrowers, investment security issuers and on other forms of short-term investment for time value of money. The carrying value may approximate fair value due to the short-term nature of their settlement dates.

+ References

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash
-URI http://asc.fasb.org/extlink&oid=6506951

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash Equivalents
-URI http://asc.fasb.org/extlink&oid=6507016

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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No definition available.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13(3)(a))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Fair value of investments in debt securities classified as held-to-maturity.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

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-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

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-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

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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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Glossary Loan
-URI http://asc.fasb.org/extlink&oid=6517073

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