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	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	$ 431,725	$ 477,944
Gross Unrealized Gain	129	63
Gross Unrealized Loss	(132)	(262)
Cumulative Translation Adjustment	(8,922)	(6,552)
Fair Value	422,800	471,193
Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	133,791	149,598
Fair Value	133,791	149,598
Money Market Accounts [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	98,993	124,432
Fair Value	98,993	124,432
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	126,798	118,242
Gross Unrealized Gain	60	54
Gross Unrealized Loss	(132)	(254)
Cumulative Translation Adjustment	(8,922)	(4,966)
Fair Value	117,804	113,076
U.S. Treasuries And Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	69,231	73,919
Gross Unrealized Gain	69	1
Gross Unrealized Loss		(8)
Fair Value	69,300	73,912
Foreign Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost		8,841
Gross Unrealized Gain		8
Cumulative Translation Adjustment		(1,586)
Fair Value		7,263
Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	2,912	2,912
Fair Value	$ 2,912	$ 2,912