CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (unaudited) - USD ($) $ in Thousands	Total	Impact of ASC 326 Adoption	Total Stockholders’ Equity	Total Stockholders’ Equity Impact of ASC 326 Adoption	Common Stock	Retained Earnings	Retained Earnings Impact of ASC 326 Adoption	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Noncontrolling Interest
Balance (in shares) at Dec. 31, 2019					25,444,275
Beginning balance at Dec. 31, 2019	$ 598,100		$ 598,011		$ 114,858	$ 475,247		$ 12,059	$ (4,153)	$ 89
Increase (Decrease) in Stockholders' Equity
Net income	59,745		59,745			59,745
Other comprehensive income (loss), net of tax	13,165		13,165					13,165
Cash dividends declared and paid	(22,951)		(22,951)			(22,951)
Treasury shares purchased under share repurchase plan (in shares)					(289,101)
Treasury shares purchased under share repurchase plan	(10,012)		(10,012)						(10,012)
Treasury shares purchased under deferred directors' plan (in shares)					(10,450)
Treasury shares purchased under deferred directors' plan	$ 0		0		$ 480				(480)
Treasury shares sold and distributed under deferred directors' plan (in shares)	5,748
Treasury shares sold and distributed under deferred directors' plan	$ 0		0		$ (119)				119
Stock activity under equity compensation plans (in shares)					85,899
Stock activity under equity compensation plans	(2,030)		(2,030)		$ (2,030)
Stock based compensation expense	822		822		$ 822
Balance (in shares) at Sep. 30, 2020					25,236,371
Ending balance at Sep. 30, 2020	636,839		636,750		$ 114,011	512,041		25,224	(14,526)	89
Balance (in shares) at Jun. 30, 2020					25,233,280
Beginning balance at Jun. 30, 2020	620,892		620,803		$ 113,424	496,891		24,802	(14,314)	89
Increase (Decrease) in Stockholders' Equity
Net income	22,776		22,776			22,776
Other comprehensive income (loss), net of tax	422		422					422
Cash dividends declared and paid	(7,626)		(7,626)			(7,626)
Treasury shares purchased under deferred directors' plan (in shares)					(4,709)
Treasury shares purchased under deferred directors' plan	0		0		$ 212				(212)
Stock activity under equity compensation plans (in shares)					7,800
Stock activity under equity compensation plans	0		0		$ 0
Stock based compensation expense	375		375		$ 375
Balance (in shares) at Sep. 30, 2020					25,236,371
Ending balance at Sep. 30, 2020	636,839		636,750		$ 114,011	512,041		25,224	(14,526)	89
Balance (in shares) at Dec. 31, 2020					25,239,748
Beginning balance at Dec. 31, 2020	$ 657,184	$ (6,951)	657,095	$ (6,951)	$ 114,927	529,005	$ (6,951)	27,744	(14,581)	89
Increase (Decrease) in Stockholders' Equity
Accounting standards update	ASU 2016-13
Net income	$ 71,450		71,450			71,450
Other comprehensive income (loss), net of tax	(16,812)		(16,812)					(16,812)
Cash dividends declared and paid	(25,986)		(25,986)			(25,986)
Treasury shares purchased under deferred directors' plan (in shares)					(7,959)
Treasury shares purchased under deferred directors' plan	0		0		$ 496				(496)
Treasury shares sold and distributed under deferred directors' plan (in shares)					5,664
Treasury shares sold and distributed under deferred directors' plan	0		0		$ (115)				115
Stock activity under equity compensation plans (in shares)					61,725
Stock activity under equity compensation plans	(1,818)		(1,818)		$ (1,818)
Stock based compensation expense	6,135		6,135		$ 6,135
Balance (in shares) at Sep. 30, 2021					25,299,178
Ending balance at Sep. 30, 2021	683,202		683,113		$ 119,625	567,518		10,932	(14,962)	89
Balance (in shares) at Jun. 30, 2021					25,289,966
Beginning balance at Jun. 30, 2021	677,471		677,382		$ 117,796	552,063		22,271	(14,748)	89
Increase (Decrease) in Stockholders' Equity
Net income	24,119		24,119			24,119
Other comprehensive income (loss), net of tax	(11,339)		(11,339)					(11,339)
Cash dividends declared and paid	(8,664)		(8,664)			(8,664)
Treasury shares purchased under deferred directors' plan (in shares)					(3,383)
Treasury shares purchased under deferred directors' plan	0		0		$ 214				(214)
Treasury shares sold and distributed under deferred directors' plan (in shares)					0
Treasury shares sold and distributed under deferred directors' plan	0		0						0
Stock activity under equity compensation plans (in shares)					12,595
Stock activity under equity compensation plans	(170)		(170)		$ (170)
Stock based compensation expense	1,785		1,785		$ 1,785
Balance (in shares) at Sep. 30, 2021					25,299,178
Ending balance at Sep. 30, 2021	$ 683,202		$ 683,113		$ 119,625	$ 567,518		$ 10,932	$ (14,962)	$ 89