Cash, Cash Equivalents And Short-Term Investments (Unrealized Gains And Losses Related To Short-Term Investments Designated As Available-For-Sale) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	$ 360,435	$ 335,867
Gross Unrealized Gain	89	4
Gross Unrealized Loss	(182)	(283)
Cumulative Translation Adjustment	(1,942)	(2,670)
Fair Value	358,400	332,918
Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	217,112	165,251
Cumulative Translation Adjustment	(406)	(1,551)
Fair Value	216,706	163,700
Money Market Accounts [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	68,577	87,429
Fair Value	68,577	87,429
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	72,986	69,442
Gross Unrealized Gain	89	2
Gross Unrealized Loss	(182)	(281)
Cumulative Translation Adjustment	(1,536)	(1,119)
Fair Value	71,357	68,044
U.S. Treasuries And Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost		4,419
Gross Unrealized Loss		(2)
Fair Value		4,417
Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	1,760	9,326
Gross Unrealized Gain		2
Fair Value	$ 1,760	$ 9,328

Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Attributable To Bonds Net Of Tax

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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26610-111562

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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563

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- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563

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- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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