Fair Value Of Financial Instruments (Financial Instruments Measured At Fair Value On Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Derivatives, Fair Value [Line Items]
Cash and cash equivalents, Carrying Amount	$ 114,094	$ 44,791	$ 108,172	$ 76,315
Short-term investments (held-to-maturity), Carrying Amount	55,694	20,069
Total short-term investments, Carrying Amount	55,694	20,070
Total cash and cash equivalents and short-term investments, Carrying Amount	169,788	64,860
Total cash and cash equivalents and investments, Carrying Amount	172,368	66,140
Total cash and cash equivalents and short term investments, Estimated Fair Value	169,788	64,784
Total cash and cash equivalents and investments, Estimated Fair Value	172,368	66,064
Assets and Liabilities Measured at Fair Value	114,094	44,792
Certificates Of Deposit [Member]
Derivatives, Fair Value [Line Items]
Short-term investments (held-to-maturity), Carrying Amount	55,694	20,069
Short-term investments (held-to-maturity), Estimated Fair Value	55,694	19,992
Equity Securities [Member]
Derivatives, Fair Value [Line Items]
Short-term investments (available-for-sale), Estimated Fair Value		1
Assets and Liabilities Measured at Fair Value		1
Restricted Cash [Member]
Derivatives, Fair Value [Line Items]
Cash and cash equivalents, Carrying Amount	2,580	1,280
Cash and cash equivalents, Estimated Fair Value	2,580	1,280
Level 1 [Member]
Derivatives, Fair Value [Line Items]
Total cash and cash equivalents and short term investments, Estimated Fair Value	169,788	44,791
Total cash and cash equivalents and investments, Estimated Fair Value	172,368	44,791
Level 1 [Member] | Certificates Of Deposit [Member]
Derivatives, Fair Value [Line Items]
Short-term investments (held-to-maturity), Estimated Fair Value	55,694
Level 1 [Member] | Restricted Cash [Member]
Derivatives, Fair Value [Line Items]
Cash and cash equivalents, Estimated Fair Value	2,580
Level 2 [Member]
Derivatives, Fair Value [Line Items]
Total cash and cash equivalents and short term investments, Estimated Fair Value		1
Total cash and cash equivalents and investments, Estimated Fair Value		1
Level 2 [Member] | Equity Securities [Member]
Derivatives, Fair Value [Line Items]
Short-term investments (available-for-sale), Estimated Fair Value		1
Cash And Cash Equivalents [Member]
Derivatives, Fair Value [Line Items]
Cash and cash equivalents, Carrying Amount	114,094	44,791
Cash and cash equivalents, Estimated Fair Value	114,094	44,791
Assets and Liabilities Measured at Fair Value	114,094	44,791
Cash And Cash Equivalents [Member] | Cash [Member]
Derivatives, Fair Value [Line Items]
Cash and cash equivalents, Carrying Amount	8,680	6,824
Cash and cash equivalents, Estimated Fair Value	8,680	6,824
Assets and Liabilities Measured at Fair Value	8,680	6,824
Cash And Cash Equivalents [Member] | Money Market Funds [Member]
Derivatives, Fair Value [Line Items]
Cash and cash equivalents, Carrying Amount	105,414	37,967
Cash and cash equivalents, Estimated Fair Value	105,414	37,967
Assets and Liabilities Measured at Fair Value	105,414	37,967
Cash And Cash Equivalents [Member] | Level 1 [Member]
Derivatives, Fair Value [Line Items]
Cash and cash equivalents, Estimated Fair Value	114,094	44,791
Cash And Cash Equivalents [Member] | Level 1 [Member] | Cash [Member]
Derivatives, Fair Value [Line Items]
Cash and cash equivalents, Estimated Fair Value	8,680	6,824
Cash And Cash Equivalents [Member] | Level 1 [Member] | Money Market Funds [Member]
Derivatives, Fair Value [Line Items]
Cash and cash equivalents, Estimated Fair Value	105,414	37,967
Total Short-Term Investments [Member]
Derivatives, Fair Value [Line Items]
Short-term investments (held-to-maturity), Carrying Amount	55,694
Total short-term investments, Carrying Amount		20,069
Total short-term investments	55,694	19,993
Assets and Liabilities Measured at Fair Value		1
Total Short-Term Investments [Member] | Level 1 [Member]
Derivatives, Fair Value [Line Items]
Short-term investments (held-to-maturity), Estimated Fair Value	55,694
Total Short-Term Investments [Member] | Level 2 [Member]
Derivatives, Fair Value [Line Items]
Total short-term investments		$ 1