CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Preferred Stock	Common Stock Tri Valley Bank	Common Stock United American Bank	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income / (Loss)	Tri Valley Bank	United American Bank	Total
Balance at Dec. 31, 2015	$ 19,519			$ 193,364	$ 38,773	$ (6,220)			$ 245,436
Balance (in shares) at Dec. 31, 2015	21,004			32,113,479
Increase (Decrease) in Shareholders' Equity
Net income					27,381				27,381
Other comprehensive loss						(1,694)			(1,694)
Preferred stock exchanged for common stock	$ (19,519)			$ 19,519
Preferred stock exchanged for common stock (in shares)	(21,004)			5,601,000
Issuance of restricted stock awards, net (in shares)				79,112
Amortization of restricted stock awards, net of forfeitures				$ 479					479
Cash dividend declared					(13,627)				(13,627)
Stock option expense, net of forfeitures and taxes				937					937
Stock options exercised				$ 938					938
Stock options exercised (in shares)				147,416
Balance at Dec. 31, 2016				$ 215,237	52,527	(7,914)			259,850
Balance (in shares) at Dec. 31, 2016				37,941,007
Increase (Decrease) in Shareholders' Equity
Net income					23,828				23,828
Other comprehensive loss						(319)			(319)
Issuance of restricted stock awards, net (in shares)				64,136
Amortization of restricted stock awards, net of forfeitures				$ 912					912
Cash dividend declared					(15,238)				(15,238)
Reclassification associated with the Adoption of ASU 2018-02					1,019	(1,019)
Stock option expense, net of forfeitures				838					838
Stock options exercised				$ 1,368					1,368
Stock options exercised (in shares)				195,740
Balance at Dec. 31, 2017				$ 218,355	62,136	(9,252)			271,239
Balance (in shares) at Dec. 31, 2017				38,200,883
Increase (Decrease) in Shareholders' Equity
Net income					35,331				35,331
Other comprehensive loss						(3,129)			(3,129)
Issuance of common shares to acquire Business		$ 30,725	$ 47,280				$ 30,725	$ 47,280
Issuance of common shares to acquire Business (in shares)		1,889,613	2,826,032
Issuance of restricted stock awards, net (in shares)				95,378
Amortization of restricted stock awards, net of forfeitures				$ 1,109					1,109
Cash dividend declared					(18,464)				(18,464)
Stock option expense, net of forfeitures				708					708
Stock options exercised				$ 2,667					2,667
Stock options exercised (in shares)				276,844
Balance at Dec. 31, 2018				$ 300,844	$ 79,003	$ (12,381)			$ 367,466
Balance (in shares) at Dec. 31, 2018				43,288,750