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Shares of acquirer ratio of common stock.

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Date when the acquirer obtains control of the acquiree, in CCYY-MM-DD format.

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Number of shares of equity interests issued or issuable to acquire entity.

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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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Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination.

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Amount of equity interests of the acquirer, including instruments or interests issued or issuable in consideration for the business combination.

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The amount of financial assets (as defined) recognized as of the acquisition date.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to nondeductible expenses.

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Aggregate par or stated value of issued nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable preferred shares, par value and other disclosure concepts are in another section within stockholders' equity.

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Acquisition of First Priority Financial Corp. (Narrative) (Details) - USD ($)		3 Months Ended	9 Months Ended
	Jul. 31, 2018	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill				$ 62,840,000	$ 62,840,000
First Priority Financial Corp. [Member]
Business Acquisition [Line Items]
Acquisition completion date	Jul. 31, 2018
Shares of acquirer ratio of common stock	34.81%
Per share price	$ 11.07
Common stock shares issued to acquire the company	2,320,800
Business combination, consideration transferred, equity interests issued and issuable	$ 76,122,000
Payments to acquire businesses gross	3,807,000
Business combination consideration transferred	79,929,000
Goodwill	39,744,000
Intangible assets acquired (finite lived)	2,832,000
Intangible assets acquired (indefinite lived)	$ 205,000
Intangible assets, amortization period	10 years
Fair value of purchased loans	$ 511,623,000
Pro forma earnings		$ 5,502,000	$ 10,995,000
Severance and retention bonus expenses			1,475,000
First Priority Financial Corp. [Member] \| Excluded Acquisition-related Costs [Member]
Business Acquisition [Line Items]
Pro forma earnings			3,661,000
Income tax nondeductible expenses			$ 714,000
First Priority Financial Corp. [Member] \| Series D [Member]
Business Acquisition [Line Items]
Preferred Stock, Shares Issued	3,404
Preferred stock, value	$ 3,404,000
First Priority Financial Corp. [Member] \| Stock Options [Member]
Business Acquisition [Line Items]
Payments to acquire businesses gross	3,801,000
First Priority Financial Corp. [Member] \| Fractional Shares [Member]
Business Acquisition [Line Items]
Payments to acquire businesses gross	$ 6,000
First Priority Financial Corp. [Member] \| Common Stock [Member]
Business Acquisition [Line Items]
Per share price	$ 32.80
Business combination, consideration transferred, equity interests issued and issuable	$ 76,122,000