Interim Consolidated Statements of Shareholders' Equity and Comprehensive Income (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2019	$ 420,780	$ 448	$ 783,871	$ (4,539,154)	$ 4,499,288	$ (323,673)
Beginning balance, shares at Dec. 31, 2019		24,125,317
Exercise of stock options and restricted stock units, shares	50,372	50,372
Share based compensation, exercise value	$ 7,135		0	9,355	2,220	0
Repurchases of common stock	$ (200,000)			(200,000)
Repurchases of common stock, shares	(268,161)	(268,161)
Adjustment to Additional Paid in Capital, Share-Based Compensation	$ 4,395		4,395
Net Income (Loss) Attributable to Parent	98,115				98,115
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(24,028)					(24,028)
Ending balance at Mar. 31, 2020	306,397	$ 448	788,266	(4,729,799)	4,595,183	(347,701)
Ending balance, shares at Mar. 31, 2020		23,907,528
Beginning balance at Dec. 31, 2020	$ 282,675	$ 448	805,140	(5,283,584)	5,095,596	(334,925)
Beginning balance, shares at Dec. 31, 2020	24,125,317	23,471,841
Exercise of stock options and restricted stock units, shares	22,388	22,388
Share based compensation, exercise value	$ 5,049		1,239	4,682	872	0
Repurchases of common stock	$ (262,500)			$ (262,500)
Repurchases of common stock, shares	(224,808)	(224,808)
Adjustment to Additional Paid in Capital, Share-Based Compensation	$ 4,575		$ 4,575
Net Income (Loss) Attributable to Parent	149,663				$ 149,663
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	23,181					$ 23,181
Ending balance at Mar. 31, 2021	$ 202,643
Ending balance, shares at Mar. 31, 2021	23,907,528	23,269,421