Business Combinations - Additional Information (Detail)	Mar. 18, 2016 USD ($) Branches	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Goodwill recognized		$ 64,311,000	$ 64,311,000
Bank of America [Member]
Business Acquisition [Line Items]
Number of branches | Branches	3
Acquisition, completion date	Oct. 28, 2015
Cash consideration	$ 3,204,000
Deposits	161,231,000
Loans	289,000
Goodwill recognized	849,000
Increase in net book value of land and buildings acquired	309,000
Recognized intangible related to acquisition	2,046,000
Bank of America [Member] | Core Deposit Intangibles [Member]
Business Acquisition [Line Items]
Recognized intangible related to acquisition	$ 2,046,000
Percentage of acquired intangibles	1.50%
Finite lived intangible asset estimated useful life	7 years