Consolidated Statements Of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common stock	Treasury Stock, Common	Additional paid-in capital	Retained earnings (deficit)	Foreign currency translation adjustments	Available-for-sale investments-Change in net unrealized gains	Defined benefit pension adjustments
Balance	$ 802,883	$ 1,407	$ 0	$ 848,667	$ (416)	$ (46,237)	$ 611	$ 1,149
Balance (in shares) at Dec. 31, 2015		140,716
Shares issued under stock plans (in shares)		1,123
Shares issued under stock plans	826	$ 11	0	815	0	0	0	0
Share-based compensation expense	13,436	$ 0	0	13,436	0	0	0	0
Repurchase and retirement of common stock (in shares)		(519)
Repurchase and retirement of common stock	(7,573)	$ (5)	0	(3,140)	(4,428)	0	0	0
Pension liability adjustment	462	0	0	0	0	0	0	462
Reclassification adjustment associated with the sale of available-for-sale investments	(611)	0	0	0	0	0	(611)	0
Foreign currency translation	(7,352)	0	0	0	0	(7,352)	0	0
Reclassification of cumulative translation adjustment associated with liquidated and planned sale of subsidiaries	0
Net income	97,147	$ 0	0	0	97,147	0	0	0
Balance (in shares) at Dec. 31, 2016		141,320
Balance	899,218	$ 1,413	0	859,778	92,303	(53,589)	0	687
Shares issued under stock plans (in shares)		1,040
Shares issued under stock plans	(321)	$ 11	0	(332)	0	0	0	0
Share-based compensation expense	15,306	$ 0	0	15,306	0	0	0	0
Repurchase and retirement of common stock (in shares)		(1,077)
Repurchase and retirement of common stock	(28,000)	$ (11)	0	(6,565)	(21,424)
Dividends, Common Stock, Cash	(9,896)	0	0	0	(9,896)	0	0	0
Pension liability adjustment	(232)	0	0	0	0	0	0	(232)
Reclassification adjustment associated with the sale of available-for-sale investments	0
Foreign currency translation	29,294	0	0	0	0	29,294	0	0
Reclassification of cumulative translation adjustment associated with liquidated and planned sale of subsidiaries	1,702	0	0	0	0	1,702	0	0
Net income	85,066	$ 0	0	0	85,066	0	0	0
Balance (in shares) at Dec. 31, 2017		141,283
Balance	993,018	$ 1,413	0	867,699	147,418	(22,593)	0	919
Cumulative Effect of New Accounting Principle in Period of Adoption	881	$ 0	0	(488)	1,369	0	0	0
Shares issued under stock plans (in shares)		1,120
Shares issued under stock plans	(9,109)	$ 11	0	(9,120)	0	0	0	0
Share-based compensation expense	17,112	$ 0	$ 0	17,112	0	0	0	0
Repurchase and retirement of common stock (in shares)		(6,224)	(202)
Repurchase and retirement of common stock	(179,315)	$ (62)	$ (7,112)	(38,066)	(134,075)
Dividends, Common Stock, Cash	(39,722)	0	0	(33)	(39,755)	0	0	0
Pension liability adjustment	59	0	0	0	0	0	0	59
Reclassification adjustment associated with the sale of available-for-sale investments	0
Foreign currency translation	(10,183)	0	0	0	0	(10,183)	0	0
Reclassification of cumulative translation adjustment associated with liquidated and planned sale of subsidiaries	0
Net income	240,755	$ 0	$ 0	0	240,755	0	0	0
Balance (in shares) at Dec. 31, 2018		136,179	202
Balance	1,012,025	$ 1,362	$ 7,112	837,658	213,753	(32,776)	0	860
Cumulative Effect of New Accounting Principle in Period of Adoption	$ (590)	$ 0	$ 0	$ 0	$ (590)	$ 0	$ 0	$ 0