Marketable Securities (Summary Of Future Maturities Of Available-For-Sale Securities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized cost, maturities Less than 12 months	$ 27,054
Available-for-sale securities, Fair value, maturities Less than 12 months	27,194
Available-for-sale securities, Amortized cost, maturities Greater than 12 months	0
Available-for-sale securities, Fair value, maturities Greater than 12 months	0
Common Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized cost, maturities Less than 12 months	197
Available-for-sale securities, Fair value, maturities Less than 12 months	347
Available-for-sale securities, Amortized cost, maturities Greater than 12 months	0
Available-for-sale securities, Fair value, maturities Greater than 12 months	0
Government And Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized cost, maturities Less than 12 months	26,857
Available-for-sale securities, Fair value, maturities Less than 12 months	26,847
Available-for-sale securities, Amortized cost, maturities Greater than 12 months	0
Available-for-sale securities, Fair value, maturities Greater than 12 months	$ 0