CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Total Stockholders' Equity	Noncontrolling Interest	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
Adoption of ASU | Accounting Standards Update 2018-02		173	(173)		0		0
Adoption of ASU | Accounting Standards Update 2014-09		24			24		24
Adoption of ASU | Accounting Standards Update 2016-01		68	(68)		0		0
Net income		59,048			59,048		59,048
Other comprehensive income (loss), net of tax			(12,365)		(12,365)		(12,365)
Comprehensive income (loss)							46,683
Cash dividends declared		(18,713)			(18,713)		(18,713)
Treasury shares purchased under deferred directors' plan	$ 418			(418)	0		0
Treasury shares purchased under deferred directors' plan (in shares)	(8,602)
Treasury shares sold and distributed under deferred directors' plan	$ (115)			115	0		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	$ 4,315				4,315		4,315
Balance at Sep. 30, 2018	$ 111,045	404,394	(13,276)	(3,711)	498,452	89	498,541
Balance (in shares) at Sep. 30, 2018	25,129,796
Balance at Jun. 30, 2018	$ 109,223	390,404	(9,710)	(3,522)	486,395	89	486,484
Balance (in shares) at Jun. 30, 2018	25,126,537
Net income		20,570			20,570		20,570
Other comprehensive income (loss), net of tax			(3,566)		(3,566)		(3,566)
Comprehensive income (loss)							17,004
Cash dividends declared		(6,580)			(6,580)		(6,580)
Treasury shares purchased under deferred directors' plan	$ 189			(189)	0		0
Treasury shares purchased under deferred directors' plan (in shares)	(3,891)
Stock activity under equity compensation plans	$ 0				0		0
Stock activity under equity compensation plans (in shares)	7,150
Stock based compensation expense	$ 1,633				1,633		1,633
Balance at Sep. 30, 2018	$ 111,045	404,394	(13,276)	(3,711)	498,452	89	498,541
Balance (in shares) at Sep. 30, 2018	25,129,796
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
Adoption of ASU | Accounting Standards Update 2017-08		(1,327)			(1,327)		(1,327)
Net income		64,849			64,849		64,849
Other comprehensive income (loss), net of tax			19,658		19,658		19,658
Comprehensive income (loss)							84,507
Cash dividends declared		(21,965)			(21,965)		(21,965)
Cashless exercise of warrants (in shares)	224,066
Cashless exercise of warrants	$ 0				0		0
Treasury shares purchased under deferred directors' plan	$ 461			(461)	0		0
Treasury shares purchased under deferred directors' plan (in shares)	(10,356)
Treasury shares sold and distributed under deferred directors' plan	$ (118)			118	0		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	$ 3,626				3,626		3,626
Balance at Sep. 30, 2019	$ 114,243	460,736	13,467	(4,099)	584,347	89	584,436
Balance (in shares) at Sep. 30, 2019	25,445,400
Balance at Jun. 30, 2019	$ 112,689	446,969	9,500	(3,884)	565,274	89	565,363
Balance (in shares) at Jun. 30, 2019	25,442,300
Net income		21,454			21,454		21,454
Other comprehensive income (loss), net of tax			3,967		3,967		3,967
Comprehensive income (loss)							25,421
Cash dividends declared		(7,687)			(7,687)		(7,687)
Treasury shares purchased under deferred directors' plan	$ 215			(215)	0		0
Treasury shares purchased under deferred directors' plan (in shares)	(4,700)
Stock activity under equity compensation plans	$ (20)				(20)		(20)
Stock activity under equity compensation plans (in shares)	7,800
Stock based compensation expense	$ 1,359				1,359		1,359
Balance at Sep. 30, 2019	$ 114,243	$ 460,736	$ 13,467	$ (4,099)	$ 584,347	$ 89	$ 584,436
Balance (in shares) at Sep. 30, 2019	25,445,400