Cash and Cash Equivalents and Investments (Summary Of Cash And Cash Equivalents And Investments By Balance Sheet Classification) (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Cash And Cash Equivalents And Investments
Cash and cash equivalents, cost	$ 204,094	$ 356,533
Cash and cash equivalents, fair value	204,094	356,533	[1]
Short term investments, cost	44,126	90,466
Short-term investments, fair value	43,504	90,284	[1]
Long term investments, cost	33,554	45,647
Long-term investments, fair value	33,553	45,466	[1]
Total cash and cash equivalents and investments, cost	281,774	492,646
Total cash and cash equivalents and investments, fair value	$ 281,151	$ 492,283	[1]

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