Cash, Cash Equivalents And Short-Term Investments (Contractual Maturities Of Short-Term Investments Designated As Available-For-Sale) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Cash and Cash Equivalents [Line Items]
Adjusted Cost, Due in less than 1 year	$ 65,586
Fair Value, Due in less than 1 year	62,831
Adjusted Cost, Due in 1 to 5 years	111,399
Fair Value, Due in 1 to 5 years	110,335
Adjusted Cost, Total	176,985
Fair Value, Total	173,166
Municipal Bonds [Member]
Cash and Cash Equivalents [Line Items]
Adjusted Cost, Due in 1 to 5 years	1,465
Fair Value, Due in 1 to 5 years	1,466
Corporate Bonds [Member]
Cash and Cash Equivalents [Line Items]
Adjusted Cost, Due in 1 to 5 years	8,708
Fair Value, Due in 1 to 5 years	7,778
U.S. Treasuries And Agencies [Member]
Cash and Cash Equivalents [Line Items]
Adjusted Cost, Due in less than 1 year	46,458
Fair Value, Due in less than 1 year	46,449
Adjusted Cost, Due in 1 to 5 years	89,495
Fair Value, Due in 1 to 5 years	89,476
Foreign Government Bonds [Member]
Cash and Cash Equivalents [Line Items]
Adjusted Cost, Due in less than 1 year	16,216
Fair Value, Due in less than 1 year	13,470
Adjusted Cost, Total	11,731
Fair Value, Total	11,615
Time Deposits [Member]
Cash and Cash Equivalents [Line Items]
Adjusted Cost, Due in less than 1 year	2,912
Fair Value, Due in less than 1 year	$ 2,912