Financial Instruments Measured at Fair Value (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Fair Value Disclosures
Equity Method Investment, Ownership Percentage		8.40%
Unrealized Gain (Loss) on Securities		$ (13,693)		$ 14,651		$ (4,064)
Fair Value, Measurements, Recurring [Member]
Fair Value Disclosures
Cash and Cash Equivalents		22,883	[1]	289,938	[2]
Equity investments	[3]	38,045		52,683
Interest rate swaps - liability		(589)		(149)
Foreign exchange contracts - asset		4,163		5,499
Foreign exchange contracts - liability		(2,384)		(8,581)
Contingent consideration				(3,176)
Total Fair Value Assets And Liabilities Measured On Recurring Basis		62,118		336,214
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value Disclosures
Cash and Cash Equivalents		22,883	[1]	3,267
Equity investments	[3]	38,045		52,683
Interest rate swaps - asset				0
Interest rate swaps - liability		0
Foreign exchange contracts - asset		0		0
Foreign exchange contracts - liability		0		0
Contingent consideration				0
Total Fair Value Assets And Liabilities Measured On Recurring Basis		60,928		55,950
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value Disclosures
Cash and Cash Equivalents		0		286,671	[2]
Equity investments		0		0
Interest rate swaps - liability		(589)		(149)
Foreign exchange contracts - asset		4,163		5,499
Foreign exchange contracts - liability		(2,384)		(8,581)
Contingent consideration				0
Total Fair Value Assets And Liabilities Measured On Recurring Basis		1,190		283,440
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Disclosures
Cash and Cash Equivalents		0		0
Equity investments		0		0
Interest rate swaps - asset				0
Interest rate swaps - liability		0
Foreign exchange contracts - asset		0		0
Foreign exchange contracts - liability		0		0
Contingent consideration				(3,176)
Total Fair Value Assets And Liabilities Measured On Recurring Basis		$ 0		$ (3,176)

[1] Cash equivalents include highly liquid investments with an original maturity of less than three months.

[2] Cash equivalents at December 31, 2017 included $286,671 invested in certificates of deposit, with an original maturity of less than three months, held in anticipation of our acquisition of eInfochips, which closed in January 2018 (see Note 2).

[3] The company has an 8.4% equity ownership interest in Marubun Corporation and a portfolio of mutual funds with quoted market prices. During 2018, 2017, and 2016 the company recorded unrealized gains (losses) of $(13,693), $14,651, and $(4,064), respectively, on equity securities held at the end of each year.