Statement of Cash Flows Supplemental Disclosure - Supplemental Disclosures of Cash Flow Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Information [Line Items]
Interest on deposits and borrowings	$ 12,205	$ 8,336	$ 9,245
Income taxes	1,725	475	375
Supplemental schedule of noncash activities:
Securities transferred from available for sale to held to maturity, at fair value			103,768
Accretion of securities held to maturity	195	247	131
Transfers from premises and equipment to other assets, held for sale	1,720
Transfers from loans to real estate owned	996	971	$ 2,264
Transfers from loans to loans held for sale	27,921
Transfers from loans to other assets		6,384
James & Sons Insurance Company [Member]
Supplemental schedule of noncash activities:
Issuance of common stock		$ 1,547
Ohio Legacy Corp. [Member]
Supplemental schedule of noncash activities:
Issuance of common stock	25,816
Net assets acquired excluding cash and cash equivalents	$ 1,247