Fair Value Measurements (Schedule Of Fair Values Of Financial Instruments Measured On Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Total assets	$ 205,605	$ 262,144
Money Market Funds [Member]
Cash	66,811	101,232
Bank Time Deposits [Member]
Cash	30,797	22,773
Commercial Paper [Member]
Cash	999
Certificates of Deposit [Member]
Investments	6,233	14,402
Equity Securities [Member]
Investments	25,882	30,047
Debt Securities Issued By The U.S Treasury And Other U.S Government Corporations And Agencies [Member]
Investments	19,219	23,702
Debt Securities Issued By States Of The United States And Political Subdivisions Of The States [Member]
Investments	2,275	3,296
Debt Securities Issued By Foreign Governments [Member]
Investments	2,049
Corporate Debt Securities [Member]
Investments	51,340	66,692
Level 1 [Member]
Total assets	205,605	262,144
Level 1 [Member] | Money Market Funds [Member]
Cash	66,811	101,232
Level 1 [Member] | Bank Time Deposits [Member]
Cash	30,797	22,773
Level 1 [Member] | Commercial Paper [Member]
Cash	999
Level 1 [Member] | Certificates of Deposit [Member]
Investments	6,233	14,402
Level 1 [Member] | Equity Securities [Member]
Investments	25,882	30,047
Level 1 [Member] | Debt Securities Issued By The U.S Treasury And Other U.S Government Corporations And Agencies [Member]
Investments	19,219	23,702
Level 1 [Member] | Debt Securities Issued By States Of The United States And Political Subdivisions Of The States [Member]
Investments	2,275	3,296
Level 1 [Member] | Debt Securities Issued By Foreign Governments [Member]
Investments	2,049
Level 1 [Member] | Corporate Debt Securities [Member]
Investments	51,340	66,692
Level 2 [Member]
Total assets	0	0
Level 2 [Member] | Money Market Funds [Member]
Cash	0	0
Level 2 [Member] | Bank Time Deposits [Member]
Cash	0	0
Level 2 [Member] | Commercial Paper [Member]
Cash	0
Level 2 [Member] | Certificates of Deposit [Member]
Investments	0	0
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	0	0
Level 2 [Member] | Debt Securities Issued By States Of The United States And Political Subdivisions Of The States [Member]
Investments	0	0
Level 2 [Member] | Debt Securities Issued By Foreign Governments [Member]
Investments	0
Level 2 [Member] | Corporate Debt Securities [Member]
Investments	0	0
Level 3 [Member]
Total assets	0	0
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