Nature of Operations and Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015 USD ($) Valuation_Techniques Facilities Business shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2013 USD ($) shares
Schedule Of Accounting Policies [Line Items]
Full service facilities maintained by bank | Facilities	46
Number of business conduct | Business	0
Number of valuation techniques to measure fair value | Valuation_Techniques	3
Factor considered to be significant for fair value measurement	10.00%
Accrual of interest discontinued description	Principal or interest is past due 90 days or more, and the loan is not well secured or in the process of collection, or when serious doubt exists as to the collectability of a loan, the accrual of interest is discontinued.
Commercial loans as a percentage of total loan	46.00%
Residential real estate loans as a percentage of total loan	25.00%
Installment loans as a percentage of total loan	20.00%
Mortgage warehouse loans as a percentage of total loan	8.00%
Period in which loan sold by mortgage company	30 days
Minimum period loan held by mortgage company	90 days
Mortgage warehousing maximum pay off period	30 days
Costs are deferred due to the term	$ 0
Impaired loans charged off	90 days
Status of Non-Accrual of Loan	90 days
Impairment of Loan	30 days
Intangibles, Gross	$ 7,400,000
Goodwill	$ 49,600,000	$ 28,176,000	$ 19,748,000
Uncertain tax positions recognized	50.00%
Shares, non-dilutive | shares	2,500	2,500	0
Amount available for payment of dividend	$ 12,700,000
Cash and cash equivalents maximum maturity period	1 day
Compensation expense	$ 643,000	$ 566,000	$ 336,000
Reclassifications effect on net income	$ 0
Buildings and Improvements [Member] | Minimum [Member]
Schedule Of Accounting Policies [Line Items]
Useful Life for depreciation	3 years
Buildings and Improvements [Member] | Maximum [Member]
Schedule Of Accounting Policies [Line Items]
Useful Life for depreciation	40 years
Furniture and Equipment [Member] | Minimum [Member]
Schedule Of Accounting Policies [Line Items]
Useful Life for depreciation	2 years
Furniture and Equipment [Member] | Maximum [Member]
Schedule Of Accounting Policies [Line Items]
Useful Life for depreciation	20 years