Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Total assets	$ 515,174	$ 259,882
Liabilities, Fair Value Disclosure [Abstract]
Total liabilities	0	0
Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Total assets	1,344,917	1,597,770
Liabilities, Fair Value Disclosure [Abstract]
Total liabilities	3,783	9,692
Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Total assets	6,162	6,073
Liabilities, Fair Value Disclosure [Abstract]
Total liabilities	0	0
Cash and Cash Equivalents [Member] \| Cash [Member] \| Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	295,170	230,370
Cash and Cash Equivalents [Member] \| Cash [Member] \| Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	0	0
Cash and Cash Equivalents [Member] \| Cash [Member] \| Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	0	0
Cash and Cash Equivalents [Member] \| Money Market Funds [Member] \| Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	220,004	29,512
Cash and Cash Equivalents [Member] \| Money Market Funds [Member] \| Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	0	0
Cash and Cash Equivalents [Member] \| Money Market Funds [Member] \| Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	0	0
Cash and Cash Equivalents [Member] \| Corporate Securities [Member] \| Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	0	0
Cash and Cash Equivalents [Member] \| Corporate Securities [Member] \| Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	12,420	267
Cash and Cash Equivalents [Member] \| Corporate Securities [Member] \| Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	0	0
Available-for-sale Securities [Member] \| Corporate Securities [Member] \| Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	0	0
Available-for-sale Securities [Member] \| Corporate Securities [Member] \| Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	673,193	788,042
Available-for-sale Securities [Member] \| Corporate Securities [Member] \| Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	6,162	6,073
Available-for-sale Securities [Member] \| Agency Securities [Member] \| Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	0	0
Available-for-sale Securities [Member] \| Agency Securities [Member] \| Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	578,881	638,313
Available-for-sale Securities [Member] \| Agency Securities [Member] \| Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	0	0
Available-for-sale Securities [Member] \| Municipal securities [Member] \| Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	0	0
Available-for-sale Securities [Member] \| Municipal securities [Member] \| Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	15,493	48,730
Available-for-sale Securities [Member] \| Municipal securities [Member] \| Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	0	0
Available-for-sale Securities [Member] \| Government securities [Member] \| Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	0	0
Available-for-sale Securities [Member] \| Government securities [Member] \| Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	63,739	121,212
Available-for-sale Securities [Member] \| Government securities [Member] \| Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	0	0
Accrued Expenses and Other Current Liabilities [Member] \| Level 1 [Member]
Liabilities, Fair Value Disclosure [Abstract]
Foreign currency derivatives	0	0
Accrued Expenses and Other Current Liabilities [Member] \| Level 2 [Member]
Liabilities, Fair Value Disclosure [Abstract]
Foreign currency derivatives	3,783	9,692
Accrued Expenses and Other Current Liabilities [Member] \| Level 3 [Member]
Liabilities, Fair Value Disclosure [Abstract]
Foreign currency derivatives	0	0
Foreign Exchange Contract [Member] \| Prepaid Expenses and Other Current Assets [Member] \| Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Prepaid expenses and other current assets	0	0
Foreign Exchange Contract [Member] \| Prepaid Expenses and Other Current Assets [Member] \| Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Prepaid expenses and other current assets	1,191	1,206
Foreign Exchange Contract [Member] \| Prepaid Expenses and Other Current Assets [Member] \| Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Prepaid expenses and other current assets	0	0
Estimate of Fair Value Measurement [Member]
Assets, Fair Value Disclosure [Abstract]
Total assets	1,866,253	1,863,725
Liabilities, Fair Value Disclosure [Abstract]
Total liabilities	3,783	9,692
Estimate of Fair Value Measurement [Member] \| Cash and Cash Equivalents [Member] \| Cash [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	295,170	230,370
Estimate of Fair Value Measurement [Member] \| Cash and Cash Equivalents [Member] \| Money Market Funds [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	220,004	29,512
Estimate of Fair Value Measurement [Member] \| Cash and Cash Equivalents [Member] \| Corporate Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	12,420	267
Estimate of Fair Value Measurement [Member] \| Available-for-sale Securities [Member] \| Corporate Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	679,355	794,115
Estimate of Fair Value Measurement [Member] \| Available-for-sale Securities [Member] \| Agency Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	578,881	638,313
Estimate of Fair Value Measurement [Member] \| Available-for-sale Securities [Member] \| Municipal securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	15,493	48,730
Estimate of Fair Value Measurement [Member] \| Available-for-sale Securities [Member] \| Government securities [Member]
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	63,739	121,212
Estimate of Fair Value Measurement [Member] \| Accrued Expenses and Other Current Liabilities [Member]
Liabilities, Fair Value Disclosure [Abstract]
Foreign currency derivatives	3,783	9,692
Estimate of Fair Value Measurement [Member] \| Foreign Exchange Contract [Member] \| Prepaid Expenses and Other Current Assets [Member]
Assets, Fair Value Disclosure [Abstract]
Prepaid expenses and other current assets	$ 1,191	$ 1,206

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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- References

No definition available.

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash

-URI http://asc.fasb.org/extlink&oid=6506951

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash Equivalents

-URI http://asc.fasb.org/extlink&oid=6507016

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- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624163-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226000-175313

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 20

-Section 50

-Paragraph 4D

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=51814546&loc=SL51823488-111719

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- Definition

Fair value portion of liability contracts related to the exchange of different currencies, including, but not limited to, foreign currency options, forward (delivery or nondelivery) contracts, and swaps entered into.

+ References

No definition available.

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Trading Securities

-URI http://asc.fasb.org/extlink&oid=6526789

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 35

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Available-for-Sale Securities

-URI http://asc.fasb.org/extlink&oid=6505594

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph a, f, g

-Article 7

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- Definition

Fair value of financial and nonfinancial obligations.

+ References

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

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