Consolidated Statement of Shareholders' Equity - 6 months ended Jun. 30, 2015 - USD ($) $ in Thousands	Total	Common Stock	Common Stock NB&T Financial Group, Inc.	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Balance, December 31, 2014 at Dec. 31, 2014	$ 340,118	$ 265,742		$ 90,391	$ (1,301)	$ (14,714)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	4,224			4,224
Other comprehensive income, net of tax	1,703				1,703
Cash dividends declared	(5,030)			(5,030)
Reissuance of treasury stock for common stock option exercises	0					0
Tax benefit from exercise of stock options	63	63
Reissuance of treasury stock for deferred compensation plan for Boards of Directors	155					155
Purchase of treasury stock	(593)					(593)
Common shares issued under dividend reinvestment plan	204	204
Common shares issued under compensation plan for Board of Directors	109	(6)				115
Common shares issued under employee stock purchase plan	158	(21)				179
Stock-based compensation expense	1,026	1,026
Issuance of common shares related to acquisition of NB&T Financial Group, Inc.	76,027		$ 76,027
Balance, June 30, 2015 at Jun. 30, 2015	$ 418,164	$ 343,035		$ 89,585	$ 402	$ (14,858)