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, 2016	$ 104,405	$ 327,873	$ (2,387)	$ (2,913)	$ 426,978	$ 89	$ 427,067
Balance (in shares) at Dec. 31, 2016	24,937,865
Net income		57,330			57,330		57,330
Other comprehensive income (loss), net of tax			1,717		1,717		1,717
Cash dividends declared		(21,409)			(21,409)		(21,409)
Treasury shares purchased under deferred directors' plan	$ 495			(495)	0		0
Treasury shares purchased under deferred directors' plan (in shares)	(10,748)
Stock activity under equity incentive plans	$ (1,736)				(1,736)		(1,736)
Stock activity under equity incentive plans (in shares)	98,816
Stock based compensation expense	$ 5,698				5,698		5,698
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		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		0
Treasury shares purchased under deferred directors' plan (in shares)	(9,625)
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)	106,829
Stock based compensation expense	$ 5,608				5,608		5,608
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		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 warrents	$ 0				0		0
Cashless exercise of warrents (in shares)	224,066
Treasury shares purchased under deferred directors' plan	$ 515			(515)	0		0
Treasury shares purchased under deferred directors' plan (in shares)	(11,481)
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	$ (2,109)				(2,109)		(2,109)
Stock activity under equity incentive plans (in shares)	97,218
Stock based compensation expense	$ 4,187				4,187		4,187
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