CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Retained Earnings Adoption of ASU 2017-08	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Total Stockholders' Equity Adoption of ASU 2017-08	Total Stockholders' Equity	Noncontrolling Interest	Adoption of ASU 2017-08	Total
Balance at Dec. 31, 2017	$ 108,862		$ 363,794	$ (670)	$ (3,408)		$ 468,578	$ 89		$ 468,667
Balance (in shares) at Dec. 31, 2017	25,025,933
Increase (Decrease) in Stockholders' Equity
Net income			80,411				80,411			80,411
Other comprehensive income (loss), net of tax				(5,280)			(5,280)			(5,280)
Cash dividends declared			(25,291)				(25,291)			(25,291)
Treasury shares purchased under deferred directors' plan	$ (463)				463		0
Treasury shares purchased under deferred directors' plan (in shares)	(9,625)
Treasury shares sold and distributed under deferred directors' plan	$ (115)				115		0
Treasury shares sold and distributed under deferred directors' plan (in shares)	5,636
Stock activity under equity compensation plans	$ 2,435						2,435			2,435
Stock activity under equity compensation plans (in shares)	106,829
Stock based compensation expense	$ 5,608						5,608			5,608
Balance (Accounting Standards Update 2018-02) at Dec. 31, 2018			173	(173)			0
Balance (Accounting Standards Update 2014-09) at Dec. 31, 2018			24				24			24
Balance (Accounting Standards Update 2016-01) at Dec. 31, 2018			68	(68)			0
Balance at Dec. 31, 2018	$ 112,383		419,179	(6,191)	(3,756)		521,615	89		521,704
Balance (in shares) at Dec. 31, 2018	25,128,773
Increase (Decrease) in Stockholders' Equity
Net income			87,047				87,047			87,047
Other comprehensive income (loss), net of tax				18,250			18,250			18,250
Cash dividends declared			(29,652)				(29,652)			(29,652)
Cashless exercise of warrants							0
Cashless exercise of warrants (in shares)	224,066
Treasury shares purchased under deferred directors' plan	$ (515)				515		0
Treasury shares purchased under deferred directors' plan (in shares)	(11,481)
Treasury shares sold and distributed under deferred directors' plan	$ (118)				118		0
Treasury shares sold and distributed under deferred directors' plan (in shares)	5,699
Stock activity under equity compensation plans	$ 2,109						2,109			2,109
Stock activity under equity compensation plans (in shares)	97,218
Stock based compensation expense	$ 4,187						4,187			4,187
Balance (Accounting Standards Update 2016-01) at Dec. 31, 2019		$ (1,327)				$ (1,327)			$ (1,327)
Balance at Dec. 31, 2019	$ 114,858		475,247	12,059	(4,153)		598,011	89		598,100
Balance (in shares) at Dec. 31, 2019	25,444,275
Increase (Decrease) in Stockholders' Equity
Cumulative period adjustment made to retained earnings										475,247
Net income			84,337				84,337			84,337
Other comprehensive income (loss), net of tax				15,685			15,685			15,685
Cash dividends declared			(30,579)				(30,579)			(30,579)
Treasury shares purchased under share repurchase plan	$ 0				(10,012)		(10,012)			(10,012)
Treasury shares purchased under share repurchase plan (in shares)	(289,101)
Treasury shares purchased under deferred directors' plan	$ (535)				535		0
Treasury shares purchased under deferred directors' plan (in shares)	(11,566)
Treasury shares sold and distributed under deferred directors' plan	$ (119)				119		0
Treasury shares sold and distributed under deferred directors' plan (in shares)	5,748
Stock activity under equity compensation plans	$ 2,137						2,137			2,137
Stock activity under equity compensation plans (in shares)	90,392
Stock based compensation expense	$ 1,790						1,790			1,790
Balance at Dec. 31, 2020	$ 114,927		$ 529,005	$ 27,744	$ (14,581)		$ 657,095	$ 89		657,184
Balance (in shares) at Dec. 31, 2020	25,239,748
Increase (Decrease) in Stockholders' Equity
Cumulative period adjustment made to retained earnings										$ 529,005