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	Mar. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	$ 332,059	$ 338,981
Gross Unrealized Gain	44	58
Gross Unrealized Loss	(34)	(48)
Cumulative Translation Adjustment	(4,764)	(3,829)
Fair Value	327,305	335,162
Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	134,054	141,340
Fair Value	134,054	141,340
Money Market Accounts [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	38,001	20,656
Fair Value	38,001	20,656
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	1,432	1,465
Gross Unrealized Gain	2	1
Fair Value	1,434	1,466
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	17,835	8,708
Gross Unrealized Loss	(34)	(20)
Cumulative Translation Adjustment	(2,314)	(910)
Fair Value	15,487	7,778
U.S. Treasuries And Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	119,006	135,953
Gross Unrealized Gain	19
Gross Unrealized Loss		(28)
Fair Value	119,025	135,925
Foreign Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	18,819	27,947
Gross Unrealized Gain	23	57
Cumulative Translation Adjustment	(2,450)	(2,919)
Fair Value	16,392	25,085
Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	2,912	2,912
Fair Value	$ 2,912	$ 2,912