Fair Value Measurements (Schedule Of Fair Values Of Financial Instruments Measured On Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Total assets	$ 421,166us-gaap_AssetsFairValueDisclosure	$ 262,144us-gaap_AssetsFairValueDisclosure
Business Combination, Contingent Consideration, Liability	45,300	7,000	2,500
Derivative Liability, Fair Value, Gross Liability	742
Financial Liabilities Fair Value Disclosure	15,742
Money Market Funds [Member]
Cash	212,645	101,231
Bank Time Deposits [Member]
Cash	51,807	22,773
Certificates of Deposit [Member]
Investments	65	14,403
Equity Securities [Member]
Investments	36,245	30,047
US Treasury and Government [Member]
Investments	26,844	23,702
US States and Political Subdivisions Debt Securities [Member]
Investments	2,093	3,296
Corporate Debt Securities [Member]
Investments	91,467	66,692
Level 1 [Member]
Total assets	248,890	262,144
Business Combination, Contingent Consideration, Liability	0
Derivative Liability, Fair Value, Gross Liability	0
Financial Liabilities Fair Value Disclosure	0
Level 1 [Member] \| Money Market Funds [Member]
Cash	212,645	101,231
Level 1 [Member] \| Bank Time Deposits [Member]
Cash	0	22,773
Level 1 [Member] \| Certificates of Deposit [Member]
Investments	0	14,403
Level 1 [Member] \| Equity Securities [Member]
Investments	36,245	30,047
Level 1 [Member] \| US Treasury and Government [Member]
Investments	0	23,702
Level 1 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Investments	0	3,296
Level 1 [Member] \| Corporate Debt Securities [Member]
Investments	0	66,692
Level 2 [Member]
Total assets	172,276	0
Business Combination, Contingent Consideration, Liability	0
Derivative Liability, Fair Value, Gross Liability	742
Financial Liabilities Fair Value Disclosure	742
Level 2 [Member] \| Money Market Funds [Member]
Cash	0	0
Level 2 [Member] \| Bank Time Deposits [Member]
Cash	51,807	0
Level 2 [Member] \| Certificates of Deposit [Member]
Investments	65	0
Level 2 [Member] \| Equity Securities [Member]
Investments	0	0
Level 2 [Member] \| US Treasury and Government [Member]
Investments	26,844	0
Level 2 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Investments	2,093	0
Level 2 [Member] \| Corporate Debt Securities [Member]
Investments	91,467	0
Level 3 [Member]
Total assets	0	0
Business Combination, Contingent Consideration, Liability	15,000
Derivative Liability, Fair Value, Gross Liability	0
Financial Liabilities Fair Value Disclosure	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] \| Certificates of Deposit [Member]
Investments	0	0
Level 3 [Member] \| Equity Securities [Member]
Investments	0	0
Level 3 [Member] \| US Treasury and Government [Member]
Investments	0	0
Level 3 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Investments	0	0
Level 3 [Member] \| Corporate Debt Securities [Member]
Investments	0	0
Ookla [Member]
Business Combination, Contingent Consideration, Liability	$ 15,000

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

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

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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

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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.

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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.

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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

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-Name Accounting Standards Codification

-Topic 320

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-Name Regulation S-X (SX)

-Number 210

-Section 03

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-Subparagraph a, f, g

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-Topic 320

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