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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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

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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 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 aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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The balance of financing receivables that were collectively evaluated for impairment.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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Organization (Details)				3 Months Ended	12 Months Ended	42 Months Ended
Organization (Details)	Oct. 06, 2015	Apr. 07, 2014	May. 31, 2013	Dec. 31, 2015 USD ($) reportable_segment	Dec. 31, 2015 USD ($) acquisition bank_branch	Sep. 30, 2015 reportable_segment	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)
Business Acquisition [Line Items]
Number of Reportable Segments \| reportable_segment				1		3
Allowance For Credit Losses, Look-back Period for Estimation				23	23			5
Accounting Policies [Abstract]
Total assets				$ 21,288,490,000	$ 21,288,490,000		$ 16,234,605,000
Loans and Leases Receivable, Gross				14,528,165,000	14,528,165,000		11,904,684,000
Total deposits				15,666,182,000	15,666,182,000		11,755,128,000
Total stockholders' equity				4,397,691,000	$ 4,397,691,000		$ 3,506,230,000	$ 808,898,000	$ 589,121,000
Number of Businesses Acquired \| acquisition					28
Start of Acquisition Activities					May 01, 2000
Cumulative Effect of New Accounting Principle in Period of Adoption				$ 195,000	$ 195,000			$ (195,000)
Building [Member]
Business Acquisition [Line Items]
Property, Plant and Equipment, Useful Life					35 years
Minimum [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Property, Plant and Equipment, Useful Life					3 years
Maximum [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Property, Plant and Equipment, Useful Life					7 years
Core Deposits [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life					7 years
Core Deposits [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life					10 years
Customer Relationships [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life					4 years
Customer Relationships [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life					5 years
Square 1 Financial, Inc. [Member]
Accounting Policies [Abstract]
Business Acquisition, Effective Date of Acquisition	Oct. 06, 2015
Capitalsource, Inc. [Member]
Accounting Policies [Abstract]
Business Acquisition, Effective Date of Acquisition		Apr. 07, 2014
First California Financial Group, Inc. [Member]
Accounting Policies [Abstract]
Business Acquisition, Effective Date of Acquisition			May 31, 2013
Equity Securities [Member] \| Equity Method Investments [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage				20.00%	20.00%
Equity Securities [Member] \| Equity Method Investments [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage				50.00%	50.00%
Limited Partner [Member] \| Equity Method Investments [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage				5.00%	5.00%
Impaired Loans under $250,000 [Domain]
Business Acquisition [Line Items]
Financing Receivable, Collectively Evaluated for Impairment				$ 250,000	$ 250,000
Number of Quarters [Member]
Business Acquisition [Line Items]
Allowance For Credit Losses, Look-back Period for Estimation							20
CALIFORNIA
Business Acquisition [Line Items]
Retail Branch Locations \| bank_branch					80
SOUTH CAROLINA
Business Acquisition [Line Items]
Retail Branch Locations \| bank_branch					1