Organization (Details Textual)	3 Months Ended
	Mar. 31, 2018 USD ($) bank_branch acquisition
Business Acquisition [Line Items]
Number of Businesses Acquired | acquisition	29
CALIFORNIA
Business Acquisition [Line Items]
Retail Branch Locations | bank_branch	75
NORTH CAROLINA
Business Acquisition [Line Items]
Retail Branch Locations | bank_branch	1
Accounting Standards Update 2016-01 [Member]
Business Acquisition [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption | $	$ (529,000)
Accounting Standards Update 2018-02 [Member]
Business Acquisition [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption | $	$ 6,665,000