Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Foothills Bancorp [Member]	Foothills Bancorp [Member] Common Stock [Member]	Foothills Bancorp [Member] Additional Paid-in Capital [Member]	Tennessee Bancshares [Member]	Tennessee Bancshares [Member] Common Stock [Member]	Tennessee Bancshares [Member] Additional Paid-in Capital [Member]
BALANCE (in shares) at Dec. 31, 2017		11,152,561
BALANCE at Dec. 31, 2017	$ 205,853	$ 11,153	$ 174,009	$ 21,889	$ (1,198)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	18,102			18,102
Other comprehensive gain (loss)	$ (1,567)				(1,567)
Stock awards (in shares)	0	1,320
Stock awards	$ 9	$ 1	8
Exercise of stock options (in shares)		132,783
Exercise of stock options	1,519	$ 132	1,387
Restricted stock (in shares)		4,627
Restricted stock	0	$ 5	(5)
Common stock issued to shareholders (in shares)							1,183,232			1,458,981
Common stock issued to shareholders						$ 23,967	$ 1,183	$ 22,784	$ 34,732	$ 1,459	$ 33,273
Stock compensation expense	396		396
BALANCE (in shares) at Dec. 31, 2018		13,933,504
BALANCE at Dec. 31, 2018	283,011	$ 13,933	231,852	39,991	(2,765)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	26,548			26,548
Other comprehensive gain (loss)	$ 2,933				2,933
Stock awards (in shares)	0	3,298
Stock awards	$ 64	$ 3	61
Exercise of stock options (in shares)		31,931
Exercise of stock options	374	$ 32	342
Restricted stock (in shares)		39,500
Restricted stock	0	$ 40	(40)
Stock compensation expense	517		517
Common stock dividends ($0.05 per share)	(700)			(700)
BALANCE (in shares) at Dec. 31, 2019		14,008,233
BALANCE at Dec. 31, 2019	$ 312,747	$ 14,008	$ 232,732	$ 65,839	$ 168