Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) Multiplier	Jan. 15, 2016 shares	Dec. 31, 2014 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Period for federal funds purchased and sold	1 day
Average aggregate reserve	$ 6.5		$ 7.1
Loan non-accrual classification period	90 days
Days to charged consumer loans to the value of the collateral	90 days
Maximum time for re-evaluation (in months)	12 months
Re-evaluation period for real estate	2 years
Excess fair value of goodwill amount	$ 20.4
Percentage of carrying value for excess fair value	20.30%
Factor multiplication of value of goodwill | Multiplier	5
Other real estate owned	$ 1.2		$ 1.1
Percentage of likelihood of realization of recognized tax benefit, minimum	50.00%
Subsequent Event [Member]
Summary Of Significant Accounting Policies [Line Items]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased | shares		200,000
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Maturity period of cash equivalents	3 months