Fair Value Measurements (Schedule Of Fair Values Of Financial Instruments Measured On Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Total assets	$ 233,955	$ 246,340
Money Market Funds [Member]
Cash	113,310	99,351
Bank Time Deposits [Member]
Cash	3,681	22,093
Certificates of Deposit [Member]
Investments	20,387	34,876
Equity Securities [Member]
Investments	27,827	23,497
Debt Securities Issued By The U.S Treasury And Other U.S Government Corporations And Agencies [Member]
Investments	14,569	6,450
Debt Securities Issued By States Of The United States And Political Subdivisions Of The States [Member]
Investments	4,171	11,658
Debt Securities Issued By Foreign Governments [Member]
Investments	2,510	3,589
Corporate Debt Securities [Member]
Investments	47,500	44,826
Level 1 [Member]
Total assets	233,955	246,340
Level 1 [Member] | Money Market Funds [Member]
Cash	113,310	99,351
Level 1 [Member] | Bank Time Deposits [Member]
Cash	3,681	22,093
Level 1 [Member] | Certificates of Deposit [Member]
Investments	20,387	34,876
Level 1 [Member] | Equity Securities [Member]
Investments	27,827	23,497
Level 1 [Member] | Debt Securities Issued By The U.S Treasury And Other U.S Government Corporations And Agencies [Member]
Investments	14,569	6,450
Level 1 [Member] | Debt Securities Issued By States Of The United States And Political Subdivisions Of The States [Member]
Investments	4,171	11,658
Level 1 [Member] | Debt Securities Issued By Foreign Governments [Member]
Investments	2,510	3,589
Level 1 [Member] | Corporate Debt Securities [Member]
Investments	47,500	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] | 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] | 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