Borrowings - Subordinated Debt (Details) $ in Thousands	6 Months Ended
Jun. 30, 2018 USD ($) debenture	Jun. 30, 2017 USD ($)
Debt Instrument [Line Items]
Accretion of discount on subordinated debentures	$ 63	$ 80
Amount guaranteed, on subordinated basis, distributions and other payments on trust preferred securities	$ 8,000
Subordinated debenture
Debt Instrument [Line Items]
Number of subordinated debentures acquired \| debenture	2
Subordinated debentures	$ 4,950
Contractual value of subordinated debt	8,248
Accretion of discount on subordinated debentures	$ 63	$ 80
Debenture distribution deferral period (up to number of years)	5 years
Subordinated debenture \| NorCal Community Bancorp Trust I
Debt Instrument [Line Items]
Contractual value of subordinated debt	$ 4,124
Effective interest rate	5.40%
Subordinated debenture \| NorCal Community Bancorp Trust II
Debt Instrument [Line Items]
Contractual value of subordinated debt	$ 4,124
Effective interest rate	3.74%
LIBOR \| Subordinated debenture \| NorCal Community Bancorp Trust I
Debt Instrument [Line Items]
Basis spread on subordinated debentures	3.05%
LIBOR \| Subordinated debenture \| NorCal Community Bancorp Trust II
Debt Instrument [Line Items]
Basis spread on subordinated debentures	1.40%

Business Combinations, Number of Debt Instruments Acquired

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Debt Instrument, Distribution Deferral Period

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Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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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.

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

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Including the current and noncurrent portions, the carrying value of junior subordinated long-term debt owed to unconsolidated subsidiary trusts as of the balance sheet date. Such debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets and was initially scheduled to be repaid after one year or beyond the normal operating cycle if longer.

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