Financial Instruments And Marketable Securities (Future Maturities Of Available-For-Sale Securities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized cost, maturities less than twelve months	$ 27,048
Available-for-sale securities, Fair value, maturities less than twelve months	27,165
Available-for-sale securities, Amortized cost, maturities greater than twelve months	0
Available-for-sale securities, Fair value, maturities greater than twelve months	0
Common Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized cost, maturities less than twelve months	197
Available-for-sale securities, Fair value, maturities less than twelve months	320
Available-for-sale securities, Amortized cost, maturities greater than twelve months	0
Available-for-sale securities, Fair value, maturities greater than twelve months	0
Government And Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized cost, maturities less than twelve months	26,851
Available-for-sale securities, Fair value, maturities less than twelve months	26,845
Available-for-sale securities, Amortized cost, maturities greater than twelve months	0
Available-for-sale securities, Fair value, maturities greater than twelve months	$ 0