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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Organization (Details)		12 Months Ended
Organization (Details)	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($) reportable_segment acquisition bank_branch	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Business Acquisition [Line Items]
Number of Businesses Acquired \| acquisition		28
Proceeds from Sale and Collection of Lease Receivables		$ 138,955,000	$ 0	$ 0
Cumulative Effect of New Accounting Principle in Period of Adoption			$ 195,000
Allowance For Credit Losses, Look-back Period for Estimation		27	23
Fair Value Hedges, Net		$ 0
Derivative, Notional Amount		$ 79,800,000
Number of Reportable Segments \| reportable_segment		1
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		7 years
Furniture and Fixtures [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Property, Plant and Equipment, Useful Life		3 years
Furniture and Fixtures [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Property, Plant and Equipment, Useful Life		7 years
Building [Member]
Business Acquisition [Line Items]
Property, Plant and Equipment, Useful Life		35 years
Equity Securities [Member] \| Equity Method Investments [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage		20.00%
Equity Securities [Member] \| Equity Method Investments [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage		50.00%
Limited Partner [Member] \| Equity Method Investments [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage		5.00%
Loans Under $250,000
Business Acquisition [Line Items]
Financing Receivable, Collectively Evaluated for Impairment		$ 250,000
Pacific Western Equipment Finance [Member]
Business Acquisition [Line Items]
Proceeds from Sale and Collection of Lease Receivables	$ 139,000,000
CALIFORNIA
Business Acquisition [Line Items]
Retail Branch Locations \| bank_branch		77
NORTH CAROLINA
Business Acquisition [Line Items]
Retail Branch Locations \| bank_branch		1