Consolidated statements of changes in shareholders' equity - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income, net
Balance at Dec. 31, 2016	$ 330,498	$ 24,108	$ 213,480	$ 93,784	$ (874)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Initial fair value election on mortgage servicing rights, net of taxes of $396	615			615
Net income	52,398			52,398
Other comprehensive income (loss), net of taxes	1,674				1,674
Reclassification of the income tax effects of the Tax Cuts and Jobs Act to Retained earnings (Note 14)	0			652	(652)
Common stock issued, net of offering costs	152,721	4,807	147,914
Common stock issued in conjunction with acquisition of the Clayton Banks	52,284	1,521	50,763
Stock based compensation expense	6,760	18	6,742
Restricted stock units vested and distributed, net of shares withheld	(856)	63	(919)
Shares issued under employee stock purchase program	635	19	616
Balance at Dec. 31, 2017	596,729	30,536	418,596	147,449	148
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	80,236			80,236
Other comprehensive income (loss), net of taxes	(4,484)				(4,484)
Stock based compensation expense	7,207	17	7,190
Restricted stock units vested and distributed, net of shares withheld	(2,664)	143	(2,807)
Shares issued under employee stock purchase program	1,196	29	1,167
Dividends declared	(6,363)			(6,363)
Balance at Dec. 31, 2018	671,857	30,725	424,146	221,213	(4,227)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	83,814			83,814
Other comprehensive income (loss), net of taxes	16,365				16,365
Stock based compensation expense	7,089	12	7,077
Restricted stock units vested and distributed, net of shares withheld	(6,097)	274	(6,371)
Shares issued under employee stock purchase program	804	23	781
Dividends declared	(10,194)			(10,194)
Balance at Dec. 31, 2019	$ 762,329	$ 31,034	$ 425,633	$ 293,524	$ 12,138