Cash, Cash Equivalents, and Short-Term Investments (Details 1) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Summary of cost and estimated fair value of short-term investments
Amortized Cost of short-term investments, Due within one year	$ 38,772
Amortized Cost of short-term investments, Due within two years	6,254
Short-term investments, Amortized Cost	45,081
Estimated fair value of short-term investments, Due within one year	38,934
Estimated fair value of short-term investments, Due within two years	6,278
Short-term investments, Estimated Fair Value	$ 45,212	$ 1,587	[1]

[1] The Condensed Consolidated Balance Sheet as of December 31, 2011 has been derived from the audited consolidated financial statements at that date but does not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements.