Cash And Cash Equivalents And Investments (Summary Of Cash And Cash Equivalents And Investments By Balance Sheet Classification) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011
Cash And Cash Equivalents And Investments [Abstract]
Cash and cash equivalents, Amortized Cost	$ 220,006		$ 192,165
Cash and cash equivalents, Fair Value	220,006	[1]	192,165	[1]
Short-term investments, Amortized Cost	43,115		36,688
Short-term investments, Fair Value	43,194	[1]	36,774	[1]
Long-term investments, Amortized Cost	19,014		24,964
Long-term investments, Fair Value	19,166	[1]	24,832	[1]
Total cash and cash equivalents and investments, Amortized Cost	282,135		253,817
Total cash and cash equivalents and investments, Fair Value	$ 282,366	[1]	$ 253,771	[1]

[1] See Note 16 - Fair Value Measurements for details regarding fair value measurements.