Acquisition of Northwest Georgia Bank - Business Acquisition, Pro Forma Information (Details) - Northwest Georgia Bank - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015
Business Acquisition [Line Items]
Interest income	$ 22,516	$ 75,702
Interest expense	1,702	6,616
Net interest income	20,814	69,086
Provision for loan losses	(1,159)	(937)
Noninterest income	25,335	68,271
Noninterest expense	29,409	97,201
Income before income taxes	17,899	41,093
Income taxes	935	2,502
Net income	$ 16,964	$ 38,591
Earnings per share
Basic	$ 0.99	$ 2.25
Diluted	$ 0.99	$ 2.25