Fair Value Measurements (Schedule Of Fair Values Of Financial Instruments Measured On Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Total assets	$ 298,682	$ 246,340
Money Market Funds [Member]
Cash	94,278	99,351
Bank Time Deposits [Member]
Cash	22,463	22,093
Commercial Paper [Member]
Cash	6,998	0
Certificates of Deposit [Member]
Investments	14,263	34,876
Equity Securities [Member]
Investments	38,113	23,497
Debt Securities Issued By The U.S Treasury And Other U.S Government Corporations And Agencies [Member]
Investments	30,359	6,450
Debt Securities Issued By States Of The United States And Political Subdivisions Of The States [Member]
Investments	4,321	11,658
Debt Securities Issued By Foreign Governments [Member]
Investments	1,998	3,589
Corporate Debt Securities [Member]
Investments	85,889	44,826
Level 1 [Member]
Total assets	298,682	246,340
Level 1 [Member] | Money Market Funds [Member]
Cash	94,278	99,351
Level 1 [Member] | Bank Time Deposits [Member]
Cash	22,463	22,093
Level 1 [Member] | Commercial Paper [Member]
Cash	6,998	0
Level 1 [Member] | Certificates of Deposit [Member]
Investments	14,263	34,876
Level 1 [Member] | Equity Securities [Member]
Investments	38,113	23,497
Level 1 [Member] | Debt Securities Issued By The U.S Treasury And Other U.S Government Corporations And Agencies [Member]
Investments	30,359	6,450
Level 1 [Member] | Debt Securities Issued By States Of The United States And Political Subdivisions Of The States [Member]
Investments	4,321	11,658
Level 1 [Member] | Debt Securities Issued By Foreign Governments [Member]
Investments	1,998	3,589
Level 1 [Member] | Corporate Debt Securities [Member]
Investments	85,889	44,826
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	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	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	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	0
Level 3 [Member] | Corporate Debt Securities [Member]
Investments	$ 0	$ 0