Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Beginning balance at Dec. 31, 2018	$ 603,804	$ 239	$ (42,655)	$ 350,936	$ 304,566	$ (9,282)
Net income	34,580	0	0	0	34,580	0
Other comprehensive income	22,356	0	0	0	0	22,356
Comprehensive income	56,936	0	0	0	34,580	22,356
Cash dividends paid on common shares	(7,798)	0	0	0	(7,798)	0
Issuance under equity compensation plans, net	(1,233)	1	0	(1,234)	0	0
Share-based Payment Arrangement, Noncash Expense	1,907	0	0	1,907	0	0
Shares issued in connection with acquisition	171,885	40	0	171,845	0	0
Ending balance at Jun. 30, 2019	825,501	280	(42,655)	523,454	331,348	13,074
Beginning balance at Mar. 31, 2019	797,835	280	(42,655)	521,761	316,959	1,490
Net income	18,424	0	0	0	18,424	0
Other comprehensive income	11,584	0	0	0	0	11,584
Comprehensive income	30,008	0	0	0	18,424	11,584
Cash dividends paid on common shares	(4,035)	0	0	0	4,035	0
Issuance under equity compensation plans, net	707	0	0	707	0	0
Share-based Payment Arrangement, Noncash Expense	986	0	0	986	0	0
Ending balance at Jun. 30, 2019	825,501	280	(42,655)	523,454	331,348	13,074
Beginning balance at Dec. 31, 2019	867,185	281	(58,181)	526,599	380,737	17,749
Net income	27,502	0	0	0	27,502	0
Other comprehensive income	15,060	0	0	0	0	15,060
Comprehensive income	42,562	0	0	0	27,502	15,060
Cash dividends paid on common shares	(9,458)	0	0	0	(9,458)	0
Repurchase of common stock	(15,347)	0	(15,347)	0	0	0
Issuance under equity compensation plans, net	(894)	0	0	(894)	0	0
Share-based Payment Arrangement, Noncash Expense	2,029	0	0	2,029	0	0
Reclassification for the adoption of new accounting standards	(18,114)	0	0	0	(18,114)	0
Ending balance at Jun. 30, 2020	867,963	281	(73,528)	527,734	380,667	32,809
Beginning balance at Mar. 31, 2020	846,436	281	(73,528)	525,838	370,748	23,097
Net income	14,634	0	0	0	14,634	0
Other comprehensive income	9,712	0	0	0	0	9,712
Comprehensive income	24,346	0	0	0	14,634	9,712
Cash dividends paid on common shares	(4,715)	0	0	0	(4,715)	0
Issuance under equity compensation plans, net	827	0	0	827	0	0
Share-based Payment Arrangement, Noncash Expense	1,069	0	0	1,069	0	0
Ending balance at Jun. 30, 2020	$ 867,963	$ 281	$ (73,528)	$ 527,734	$ 380,667	$ 32,809