Condensed Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Common Stock	Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss).	Total
Balance at Dec. 31, 2015	$ 60,407	$ 703,929	$ 298,919	$ (3,871)	$ 1,059,384
Balance (in shares) at Dec. 31, 2015	24,162,657
Increase (Decrease) in Stockholders' Equity
Comprehensive income			24,494	7,376	31,870
Cash divideends declared on common stock per share			(6,771)		(6,771)
Stock options exercised	$ 46	569			615
Stock options exercised (in shares)	18,348
Restricted stock awards	$ 72	(72)
Restricted stock awards (in shares)	28,858
Stock issued pursuant to restricted stock units.	$ 90	(90)
Stock issued pursuant to restricted stock units (in shares)	35,903
Value of common stock repurchased buyback plan	$ (82)	(2,048)			(2,130)
Common stock repurchased buyback plan (in shares)	(32,900)
Common stock repurchased	$ (88)	(2,192)			(2,280)
Common stock repurchased (in shares)	(35,033)
Share-based compensation expense		1,366			1,366
Balance at Mar. 31, 2016	$ 60,445	701,462	316,642	3,505	$ 1,082,054
Balance (in shares) at Mar. 31, 2016	24,177,833				24,177,833
Balance (in shares) Preferred Stock at Mar. 31, 2016					0
Balance at Dec. 31, 2016	$ 60,576	711,307	370,916	(8,211)	$ 1,134,588
Balance (in shares) at Dec. 31, 2016	24,230,392				24,230,392
Balance (in shares) Preferred Stock at Dec. 31, 2016					0
Increase (Decrease) in Stockholders' Equity
Comprehensive income			18,264	3,327	$ 21,591
Cash divideends declared on common stock per share			(9,646)		(9,646)
Stock options exercised	$ 22	285			307
Stock options exercised (in shares)	9,002
Common stock issued for Southeastern Bank Financial Corp. acquisition	$ 12,446	422,163			434,609
Common stock issued for Southeastern Bank Financial Corp. acquisition (in shares)	4,978,338
Restricted stock awards	$ 28	(28)
Restricted stock awards (in shares)	11,273
Stock issued pursuant to restricted stock units.	$ 95	(95)
Stock issued pursuant to restricted stock units (in shares)	37,802
Common stock repurchased	$ (90)	(3,157)			(3,247)
Common stock repurchased (in shares)	(36,073)
Share-based compensation expense		1,698			1,698
Balance at Mar. 31, 2017	$ 73,077	$ 1,132,173	$ 379,534	$ (4,884)	$ 1,579,900
Balance (in shares) at Mar. 31, 2017	29,230,734				24,230,734
Balance (in shares) Preferred Stock at Mar. 31, 2017					0