Loans and Allowance for Loan Losses - Schedule of Activity of Purchased Impaired Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Purchased impaired loans	$ 46,852	$ 55,419
Allowance for loan losses	(430)	(278)
Carrying amount, net of allowance	46,422	55,141
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Purchased impaired loans	715	850
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Purchased impaired loans	25,648	32,774
Residential [Member]
Financing Receivable, Impaired [Line Items]
Purchased impaired loans	13,148	13,580
Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Purchased impaired loans	$ 7,341	$ 8,215