Condensed Consolidated Statements of Shareholders' Equity (unaudited) $ in Thousands	USD ($)
Balance at beginning of period at Dec. 31, 2016	$ 248,980
Cumulative effect of change in accounting at Dec. 31, 2016	352
Balance at beginning of period, as adjusted at Dec. 31, 2016	249,332
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	11,905
Cash dividends declared	(4,266)
Acquisition of TCSB Bancorp, Inc.	0
Issuance of common stock	57
Share based compensation	916
Share based compensation withholding obligation	(487)
Net change in accumulated other comprehensive loss, net of related tax effect	4,996
Balance at end of period at Jun. 30, 2017	262,453
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	5,931
Net change in accumulated other comprehensive loss, net of related tax effect	2,724
Balance at end of period at Jun. 30, 2017	262,453
Balance at beginning of period at Dec. 31, 2017	264,933
Cumulative effect of change in accounting at Dec. 31, 2017	0
Balance at beginning of period, as adjusted at Dec. 31, 2017	264,933
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	17,978
Cash dividends declared	(6,823)
Acquisition of TCSB Bancorp, Inc.	64,536
Issuance of common stock	147
Share based compensation	848
Share based compensation withholding obligation	(1,321)
Net change in accumulated other comprehensive loss, net of related tax effect	(3,215)
Balance at end of period at Jun. 30, 2018	337,083
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	8,817
Net change in accumulated other comprehensive loss, net of related tax effect	(712)
Balance at end of period at Jun. 30, 2018	$ 337,083