CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS EQUITY - USD ($) shares in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated other comprehensive Income (Loss)	Retained Earnings
Balance, shares at Dec. 31, 2017		1,852	1,568
Balance, amount at Dec. 31, 2017	$ 184,388,000	$ 342,000	$ (131,663,000)	$ 48,730,000	$ (1,215,000)	$ 268,194,000
Net income	34,255,000					34,255,000
Reclass from adopting ASU 2016-01	0				1,215,000	(1,215,000)
Stock-based compensation transactions, shares		1	(1)
Stock-based compensation transactions, amount	1,687,000		$ 26,000	1,661,000
Shares surrendered in stock transactions	(90,000)		$ (90,000)
Dividends	(9,473,000)					(9,473,000)
Balance, shares at Dec. 31, 2018		1,853	1,567
Balance, amount at Dec. 31, 2018	210,767,000	$ 342,000	$ (131,727,000)	50,391,000	0	291,761,000
Net income	36,761,000					36,761,000
Stock-based compensation transactions, shares		3	(3)
Stock-based compensation transactions, amount	1,698,000		$ 46,000	1,652,000
Shares surrendered in stock transactions	(579,000)		$ (579,000)
Dividends	(10,777,000)					(10,777,000)
Shares surrendered in stock transactions, shares		(1)	1
Balance, shares at Dec. 31, 2019		1,855	1,565
Balance, amount at Dec. 31, 2019	237,870,000	$ 342,000	$ (132,260,000)	52,043,000	0	317,745,000
Net income	32,115,000					32,115,000
Stock-based compensation transactions, amount	1,503,000		19,000	1,484,000
Shares surrendered in stock transactions	(55,000)		$ (55,000)
Dividends	(12,124,000)					(12,124,000)
Cumulative change in accounting principle	(36,000)					(36,000)
Adjusted Balance at January 1, 2020, shares		1,855	1,565
Adjusted Balance at January 1, 2020, amount	237,834,000	$ 342,000	$ (132,260,000)	52,043,000	0	317,709,000
Purchase of treasury stock, shares		(29)	29
Purchase of treasury stock, amount	(18,831,000)		$ (18,831,000)
Balance, shares at Dec. 31, 2020		1,826	1,594
Balance, amount at Dec. 31, 2020	$ 240,442,000	$ 342,000	$ (151,127,000)	$ 53,527,000	$ 0	$ 337,700,000