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Amount after tax and reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

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Amount after tax and reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount, after tax and reclassification adjustment, of (increase) decrease in accumulated other comprehensive income for defined benefit plan.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Capital In Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Stockholders' Equity	Noncontrolling Interest
Beginning balance (in shares) at Dec. 31, 2016		124,149,609
Beginning balance at Dec. 31, 2016	$ 150,410	$ 1,241	$ 22,018	$ 885,117	$ 3,811	$ (762,169)	$ 150,018	$ 392
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	117,206			116,982			116,982	224
Dividends declared	(20,075)			(20,075)			(20,075)
Currency translation adjustments	2,835				2,835		2,835
Derivative financial instruments	481				481		481
Defined benefit obligations	579				579		579
Available-for-sale investments	(1,438)				(1,438)		(1,438)
Exercise of stock options (in shares)		790,922
Exercise of stock options	18,645	$ 8	18,637				18,645
Shares placed in treasury	(11,174)		39,907			(51,081)	(11,174)
Stock-based compensation charges (in shares)		279,776
Stock-based compensation charges	7,098	$ 3	7,095				7,098
Distributions to noncontrolling interests	(266)							(266)
Ending balance (in shares) at Jun. 30, 2017		125,220,307
Ending balance at Jun. 30, 2017	$ 264,301	$ 1,252	87,657	982,024	6,268	(813,250)	263,951	350
Beginning balance (in shares) at Dec. 31, 2017	125,381,591	125,381,591
Beginning balance at Dec. 31, 2017	$ 285,757	$ 1,254	98,843	990,652	9,454	(814,809)	285,394	363
Recently adopted accounting standards at Dec. 31, 2017	9,926			12,171	(2,245)		9,926
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	127,147			127,104			127,104	43
Dividends declared	(32,262)			(32,262)			(32,262)
Currency translation adjustments	(6,733)				(6,733)		(6,733)
Derivative financial instruments	31				31		31
Defined benefit obligations	785				785		785
Available-for-sale investments	(44)				(44)		(44)
Exercise of stock options (in shares)		182,520
Exercise of stock options	4,324	$ 1	4,323				4,324
Shares placed in treasury	(6,017)					(6,017)	(6,017)
Stock-based compensation charges (in shares)		183,960
Stock-based compensation charges	5,755	$ 2	5,753				5,755
Distributions to noncontrolling interests	$ (352)							(352)
Ending balance (in shares) at Jun. 30, 2018	125,748,071	125,748,071
Ending balance at Jun. 30, 2018	$ 388,317	$ 1,257	$ 108,919	$ 1,097,665	$ 1,248	$ (820,826)	$ 388,263	$ 54