Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($) Multiplier	Jan. 20, 2017 shares	Dec. 31, 2015 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Period for federal funds purchased and sold	1 day
Average aggregate reserve	$ 5,000,000		$ 6,500,000
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	$ 11,300,000
Percentage of carrying value for excess fair value	10.40%
Factor multiplication of value of goodwill | Multiplier	2.5
Other real estate owned	$ 774,000		$ 1,200,000
Percentage of likelihood of realization of recognized tax benefit, minimum	50.00%
Amount of reclassification effect	$ 0
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