Merger - Schedule of Financial Information for Former TCNB Financial Corp Included in Consolidated Statement of Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		1 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015
Business Acquisition [Line Items]
Net interest income after provision for loan losses	$ 10,515	$ 9,415
Noninterest income	4,402	4,624
Net income	3,171	2,712
Former TCNB Financial Corp [Member]
Business Acquisition [Line Items]
Net interest income after provision for loan losses			252
Noninterest income			11
Net income			$ 48