Fair Value Measurements (Schedule Of Fair Values Of Financial Instruments Measured On Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Total assets	$ 246,773	$ 421,166
Business Combination, Contingent Consideration, Liability	20,000	15,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	20,000	15,000
Derivative Liability, Fair Value, Gross Liability	742	742
Financial Liabilities Fair Value Disclosure	20,742	15,742
Money Market Funds [Member]
Cash	98,089	212,645
Bank Time Deposits [Member]
Cash	2,886	51,807
Commercial Paper [Member]
Cash	7,499
Certificates of Deposit [Member]
Investments	57	65
Equity Securities [Member]
Investments	28,269	36,245
Debt Securities Issued By The U.S Treasury And Other U.S Government Corporations And Agencies [Member]
Investments	23,081	26,844
Debt Securities Issued By States Of The United States And Political Subdivisions Of The States [Member]
Investments	3,771	2,093
Corporate Debt Securities [Member]
Investments	83,121	91,467
Level 1 [Member]
Total assets	126,358	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	98,089	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	28,269	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] | Corporate Debt Securities [Member]
Investments	0	0
Level 2 [Member]
Total assets	120,415	172,276
Business Combination, Contingent Consideration, Liability	0	0
Derivative Liability, Fair Value, Gross Liability		742
Derivative 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	2,886	51,807
Level 2 [Member] | Commercial Paper [Member]
Cash	7,499
Level 2 [Member] | Certificates of Deposit [Member]
Investments	57	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	23,081	26,844
Level 2 [Member] | Debt Securities Issued By States Of The United States And Political Subdivisions Of The States [Member]
Investments	3,771	2,093
Level 2 [Member] | Corporate Debt Securities [Member]
Investments	83,121	91,467
Level 3 [Member]
Total assets	0	0
Business Combination, Contingent Consideration, Liability		15,000
Derivative Liability, Fair Value, Gross Liability	0	0
Financial Liabilities Fair Value Disclosure	20,000	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] | Corporate Debt Securities [Member]
Investments	$ 0	$ 0