General Introduction [Abstract]

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New Accounting Pronouncement Or Change In Accounting Principle Effect Of Change of Income Taxes

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Retail Branch Locations

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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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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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

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-Name Accounting Standards Codification
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-Section 50
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-Topic 805
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Amount of assets acquired at the acquisition date.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472

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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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The number of businesses acquired by the entity during the period.

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Organization (Details Textual)		3 Months Ended	6 Months Ended
Organization (Details Textual)	Apr. 06, 2017 USD ($) bank_branch	Jun. 30, 2017 USD ($)	Jun. 30, 2017 USD ($) acquisition bank_branch
Business Acquisition [Line Items]
New accounting pronouncement for change in accounting principle effect of change of income taxes		$ 1,000,000	$ 2,100,000
General Introduction [Abstract]
Number of businesses acquired \| acquisition			28
CALIFORNIA
General Introduction [Abstract]
Retail branch locations \| bank_branch			74
NORTH CAROLINA
General Introduction [Abstract]
Retail branch locations \| bank_branch			1
Retained Earnings
Business Acquisition [Line Items]
Cumulative effect of change in accounting principle		$ 420,000	$ 420,000
California United Bancorp [Member]
General Introduction [Abstract]
Retail branch locations \| bank_branch	9
Business combination, consideration transferred	$ 705,000,000
Assets acquired in merger	$ 3,000,000,000