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		38,478			38,478		38,478
Other comprehensive income (loss), net of tax			(8,799)		(8,799)		(8,799)
Comprehensive income (loss)							29,679
Cash dividends declared		(12,133)			(12,133)		(12,133)
Treasury shares purchased under deferred directors' plan	$ 229			(229)	0		0
Treasury shares purchased under deferred directors' plan (in shares)	(4,711)
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 incentive plans	$ (2,435)				(2,435)		(2,435)
Stock activity under equity incentive plans (in shares)	99,679
Stock based compensation expense	$ (2,682)				(2,682)		(2,682)
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
Balance at Mar. 31, 2018	$ 107,860	376,850	(7,988)	(3,478)	473,244	89	473,333
Balance (in shares) at Mar. 31, 2018	25,124,441
Net income		20,142			20,142		20,142
Other comprehensive income (loss), net of tax			(1,722)		(1,722)		(1,722)
Comprehensive income (loss)							18,420
Cash dividends declared		(6,588)			(6,588)		(6,588)
Treasury shares purchased under deferred directors' plan	$ 44			(44)	0		0
Treasury shares purchased under deferred directors' plan (in shares)	(904)
Stock activity under equity incentive plans	$ 48				48		48
Stock activity under equity incentive plans (in shares)	3,000
Stock based compensation expense	$ (1,271)				(1,271)		(1,271)
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
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		43,395			43,395		43,395
Other comprehensive income (loss), net of tax			15,691		15,691		15,691
Comprehensive income (loss)							59,086
Cash dividends declared		(14,278)			(14,278)		(14,278)
Cashless exercise of warrants (in shares)	224,066
Cashless exercise of warrants	$ 0				0		0
Treasury shares purchased under deferred directors' plan	$ 246			(246)	0		0
Treasury shares purchased under deferred directors' plan (in shares)	(5,656)
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 incentive plans	$ 2,089				2,089		2,089
Stock activity under equity incentive plans (in shares)	89,418
Stock based compensation expense	$ (2,267)				(2,267)		(2,267)
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
Balance at Mar. 31, 2019	$ 111,571	432,953	2,487	(3,833)	543,178	89	543,267
Balance (in shares) at Mar. 31, 2019	25,442,827
Net income		21,713			21,713		21,713
Other comprehensive income (loss), net of tax			7,013		7,013		7,013
Comprehensive income (loss)							28,726
Cash dividends declared		(7,697)			(7,697)		(7,697)
Treasury shares purchased under deferred directors' plan	$ 51			(51)	0		0
Treasury shares purchased under deferred directors' plan (in shares)	(1,078)
Stock activity under equity incentive plans					0		0
Stock activity under equity incentive plans (in shares)	551
Stock based compensation expense	$ (1,067)				(1,067)		(1,067)
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