Merger - Schedule of Recognized Identified Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands		6 Months Ended
	Mar. 06, 2015	Jun. 30, 2015	Mar. 05, 2015	Dec. 31, 2014
Net assets acquired:
Goodwill		$ 26,841		$ 21,720
Cash acquired in acquisition		$ 926
TCNB Financial Corp [Member]
Business Acquisition [Line Items]
Total purchase price	$ 17,226
Net assets acquired:
Cash and short-term investments	18,152
Loans, net	76,830		$ 76,771
Other securities	716
Premises and equipment	1,739
Accrued interest receivable	194
Goodwill	5,121		$ 5,121
Core deposit intangible	1,009
Other assets	1,265
Noninterest-bearing deposits	(18,263)
Interest-bearing deposits	(68,606)
Other liabilities	(5)
Net assets acquired	18,152
Cash acquired in acquisition	$ 926