Fair Value Measurements (Schedule Of Fair Values Of Financial Instruments Measured On Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Total assets	$ 377,630us-gaap_AssetsFairValueDisclosure	$ 421,166us-gaap_AssetsFairValueDisclosure
Business Combination, Contingent Consideration, Liability	12,000	15,000
Derivative Liability, Fair Value, Gross Liability	742	742
Financial Liabilities Fair Value Disclosure	12,742	15,742
Money Market Funds [Member]
Cash	190,559	212,645
Bank Time Deposits [Member]
Cash	21,673	51,807
Commercial Paper [Member]
Cash	17,921
Certificates of Deposit [Member]
Investments	60	65
Equity Securities [Member]
Investments	36,321	36,245
Debt Securities Issued By The U.S Treasury And Other U.S Government Corporations And Agencies [Member]
Investments	28,866	26,844
Debt Securities Issued By States Of The United States And Political Subdivisions Of The States [Member]
Investments	2,067	2,093
Debt Securities Issued By Foreign Governments [Member]
Investments	0
Corporate Debt Securities [Member]
Investments	80,163	91,467
Level 1 [Member]
Total assets	226,880	248,890
Business Combination, Contingent Consideration, Liability	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Financial Liabilities Fair Value Disclosure	0	0
Level 1 [Member] \| Money Market Funds [Member]
Cash	190,559	212,645
Level 1 [Member] \| Bank Time Deposits [Member]
Cash	0	0
Level 1 [Member] \| Commercial Paper [Member]
Cash	0
Level 1 [Member] \| Certificates of Deposit [Member]
Investments	0	0
Level 1 [Member] \| Equity Securities [Member]
Investments	36,321	36,245
Level 1 [Member] \| Debt Securities Issued By The U.S Treasury And Other U.S Government Corporations And Agencies [Member]
Investments	0	0
Level 1 [Member] \| Debt Securities Issued By States Of The United States And Political Subdivisions Of The States [Member]
Investments	0	0
Level 1 [Member] \| Debt Securities Issued By Foreign Governments [Member]
Investments	0
Level 1 [Member] \| Corporate Debt Securities [Member]
Investments	0	0
Level 2 [Member]
Total assets	150,750	172,276
Business Combination, Contingent Consideration, Liability	0	0
Derivative Liability, Fair Value, Gross Liability	742	742
Financial Liabilities Fair Value Disclosure	742	742
Level 2 [Member] \| Money Market Funds [Member]
Cash	0	0
Level 2 [Member] \| Bank Time Deposits [Member]
Cash	21,673	51,807
Level 2 [Member] \| Commercial Paper [Member]
Cash	17,921
Level 2 [Member] \| Certificates of Deposit [Member]
Investments	60	65
Level 2 [Member] \| Equity Securities [Member]
Investments	0	0
Level 2 [Member] \| Debt Securities Issued By The U.S Treasury And Other U.S Government Corporations And Agencies [Member]
Investments	28,866	26,844
Level 2 [Member] \| Debt Securities Issued By States Of The United States And Political Subdivisions Of The States [Member]
Investments	2,067	2,093
Level 2 [Member] \| Debt Securities Issued By Foreign Governments [Member]
Investments	0
Level 2 [Member] \| Corporate Debt Securities [Member]
Investments	80,163	91,467
Level 3 [Member]
Total assets	0	0
Business Combination, Contingent Consideration, Liability	12,000	15,000
Derivative Liability, Fair Value, Gross Liability	0	0
Financial Liabilities Fair Value Disclosure	12,000	15,000
Level 3 [Member] \| Money Market Funds [Member]
Cash	0	0
Level 3 [Member] \| Bank Time Deposits [Member]
Cash	0	0
Level 3 [Member] \| Commercial Paper [Member]
Cash	0
Level 3 [Member] \| Certificates of Deposit [Member]
Investments	0	0
Level 3 [Member] \| Equity Securities [Member]
Investments	0	0
Level 3 [Member] \| Debt Securities Issued By The U.S Treasury And Other U.S Government Corporations And Agencies [Member]
Investments	0	0
Level 3 [Member] \| Debt Securities Issued By States Of The United States And Political Subdivisions Of The States [Member]
Investments	0	0
Level 3 [Member] \| Debt Securities Issued By Foreign Governments [Member]
Investments	0
Level 3 [Member] \| Corporate Debt Securities [Member]
Investments	$ 0	$ 0

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)

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- Definition

Amount of liability recognized arising from contingent consideration in a business combination.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 25

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476

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-Paragraph 1

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- Definition

Amount 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. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ 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 SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 1

-Article 5

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

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-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.1)

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- Definition

Fair value, before effects of master netting arrangements, of a financial liability or 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 liabilities elected not to be offset. Excludes liabilities 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=34720828&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

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-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226000-175313

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- Definition

Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

+ 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 Available-for-Sale Securities

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

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

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-Name Accounting Standards Codification

-Glossary Trading Securities

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

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=28360136&loc=d3e22054-111558

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph a, f, g

-Article 7

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-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 35

-Paragraph 1

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

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