Consolidated Statement of Shareholders' Equity - 9 months ended Sep. 30, 2015 - USD ($) $ in Thousands	Total	Common Shares	Common Shares 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	8,358			8,358
Other comprehensive income, net of tax	6,286				6,286
Cash dividends declared	(7,789)			(7,789)
Tax benefit from exercise of stock options	63	63
Reissuance of treasury stock for deferred compensation plan for Boards of Directors	184					184
Purchase of treasury stock	(628)					(628)
Common shares issued under dividend reinvestment plan	299	299
Common shares issued under compensation plan for Board of Directors	155	23				178
Common shares issued under employee stock purchase plan	(255)	(35)				(290)
Stock-based compensation expense	1,432	1,432
Issuance of common shares related to acquisition of NB&T Financial Group, Inc.	76,027		$ 76,027
Balance, September 30, 2015 at Sep. 30, 2015	$ 424,760	$ 343,505		$ 90,960	$ 4,985	$ (14,690)