Condensed Consolidated Statements of Shareholders' Equity (unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Total
Balance at beginning of period at Dec. 31, 2017	$ 324,986	$ (54,054)	$ (5,999)	$ 264,933
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		17,978		17,978
Cash dividends declared	0	(6,823)	0	(6,823)
Acquisition of TCSB Bancorp, Inc.	64,536	0	0	64,536
Repurchase of common stock	0
Issuance of common stock	147	0	0	147
Share based compensation	848	0	0	848
Share based compensation withholding obligation	(1,321)	0	0	(1,321)
Other comprehensive income (loss)	0	0	(3,215)	(3,215)
Balances at end of period at Jun. 30, 2018	389,196	(42,899)	(9,214)	337,083
Balance at beginning of period at Mar. 31, 2018	324,518	(48,099)	(8,502)	267,917
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		8,817		8,817
Cash dividends declared	0	(3,617)	0	(3,617)
Acquisition of TCSB Bancorp, Inc.	64,536	0	0	64,536
Issuance of common stock	134	0	0	134
Share based compensation	441	0	0	441
Share based compensation withholding obligation	(433)	0	0	(433)
Other comprehensive income (loss)	0	0	(712)	(712)
Balances at end of period at Jun. 30, 2018	389,196	(42,899)	(9,214)	337,083
Balance at beginning of period at Dec. 31, 2018	377,372	(28,270)	(10,108)	338,994
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		20,111		20,111
Cash dividends declared	0	(8,458)	0	(8,458)
Repurchase of common stock	(25,782)	0	0	(25,782)
Issuance of common stock	282	0	0	282
Share based compensation	888	0	0	888
Share based compensation withholding obligation	(866)	0	0	(866)
Other comprehensive income (loss)	0	0	5,677	5,677
Balances at end of period at Jun. 30, 2019	351,894	(16,617)	(4,431)	330,846
Balance at beginning of period at Mar. 31, 2019	374,678	(23,135)	(6,817)	344,726
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		10,730		10,730
Cash dividends declared	0	(4,212)	0	(4,212)
Repurchase of common stock	(23,252)	0	0	(23,252)
Share based compensation	468	0	0	468
Other comprehensive income (loss)	0	0	2,386	2,386
Balances at end of period at Jun. 30, 2019	$ 351,894	$ (16,617)	$ (4,431)	$ 330,846