Cash, Cash Equivalents And Short-Term Investments (Unrealized Gains And Losses Related To Short-Term Investments Designated As Available-For-Sale) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Cash and Cash Equivalents [Line Items]
Adjusted Cost	$ 338,981	$ 370,418
Gross Unrealized Gain	58	253
Gross Unrealized Loss	(48)	(77)
Cumulative Translation Adjustment	(3,829)	(4,482)
Fair Value	335,162	366,112
Cash [Member]
Cash and Cash Equivalents [Line Items]
Adjusted Cost	141,340	106,431
Fair Value	141,340	106,431
Money Market Accounts [Member]
Cash and Cash Equivalents [Line Items]
Adjusted Cost	20,656	22,677
Fair Value	20,656	22,677
Municipal Bonds [Member]
Cash and Cash Equivalents [Line Items]
Adjusted Cost	1,465	12,381
Gross Unrealized Gain	1	11
Fair Value	1,466	12,392
Corporate Bonds [Member]
Cash and Cash Equivalents [Line Items]
Adjusted Cost	8,708	18,631
Gross Unrealized Loss	(20)	(67)
Cumulative Translation Adjustment	(910)
Fair Value	7,778	18,564
U.S. Treasuries And Agencies [Member]
Cash and Cash Equivalents [Line Items]
Adjusted Cost	135,953	170,926
Gross Unrealized Gain		2
Gross Unrealized Loss	(28)	(9)
Fair Value	135,925	170,919
Foreign Government Bonds [Member]
Cash and Cash Equivalents [Line Items]
Adjusted Cost	27,947	36,460
Gross Unrealized Gain	57	240
Gross Unrealized Loss		(1)
Cumulative Translation Adjustment	(2,919)	(4,482)
Fair Value	25,085	32,217
Time Deposits [Member]
Cash and Cash Equivalents [Line Items]
Adjusted Cost	2,912	2,912
Fair Value	$ 2,912	$ 2,912