Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning balance at Dec. 31, 2020	$ 577,932	$ 544	$ 63,261	$ 723,365	$ (58,653)	$ (150,585)
Increase (Decrease) in Stockholders' Equity
Net income (loss)	9,804			9,804
Other comprehensive income (loss)	(6,160)				(6,160)
Comprehensive income (loss)	3,644
Cash dividends declared	(12,235)			(12,235)
Share-based compensation expense	2,537		2,537
Delivery of treasury shares:
RSUs and PSAs	(633)		(3,002)			2,369
Ending balance at Jun. 30, 2021	$ 571,245	544	62,796	720,934	(64,813)	(148,216)
Delivery of treasury shares:
Common Stock, Dividends, Per Share, Declared	$ 0.275
Beginning balance at Mar. 31, 2021	$ 571,061	544	62,576	725,756	(68,493)	(149,322)
Increase (Decrease) in Stockholders' Equity
Net income (loss)	1,410			1,410
Other comprehensive income (loss)	3,680				3,680
Comprehensive income (loss)	5,090
Cash dividends declared	(6,232)			(6,232)
Share-based compensation expense	1,329		1,329
Delivery of treasury shares:
RSUs and PSAs	(3)		(1,109)			1,106
Ending balance at Jun. 30, 2021	$ 571,245	544	62,796	720,934	(64,813)	(148,216)
Delivery of treasury shares:
Common Stock, Dividends, Per Share, Declared	$ 0.14
Beginning balance at Dec. 31, 2021	$ 542,762	544	64,779	705,600	(80,304)	(147,857)
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(110,379)			(110,379)
Other comprehensive income (loss)	(31,109)				(31,109)
Comprehensive income (loss)	(141,488)
Cash dividends declared	(12,534)			(12,534)
Share-based compensation expense	2,419		2,419
Delivery of treasury shares:
RSUs and PSAs	(1,237)		(4,643)			3,406
Ending balance at Jun. 30, 2022	$ 389,922	544	62,555	582,687	(111,413)	(144,451)
Delivery of treasury shares:
Common Stock, Dividends, Per Share, Declared	$ 0.14
Beginning balance at Mar. 31, 2022	$ 416,733	544	61,873	591,012	(91,424)	(145,272)
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(2,052)			(2,052)
Other comprehensive income (loss)	(19,989)				(19,989)
Comprehensive income (loss)	(22,041)
Cash dividends declared	(6,273)			(6,273)
Share-based compensation expense	1,510		1,510
Delivery of treasury shares:
RSUs and PSAs	(7)		(828)			821
Ending balance at Jun. 30, 2022	$ 389,922	$ 544	$ 62,555	$ 582,687	$ (111,413)	$ (144,451)
Delivery of treasury shares:
Common Stock, Dividends, Per Share, Declared	$ 0.14