Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2012

Fair Value Measurements [Abstract]

Fair value measurements of Company's financial assets and liabilities

The Company’s financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used in such measurements are as follows as of September 30, 2012 and December 31, 2011 (in thousands):

	September 30, 2012 (unaudited)
Description	Level 1		Level 2		Level 3		Total
Money market fund	$	18,088	$	—	$	—	$	18,088
Government-sponsored agencies		—		6,007		—		6,007
Commercial paper		—		32,132		—		32,132
Corporate debt securities		—		71,295		—		71,295
Total assets	$	18,088	$	109,434	$	—	$	127,522

	December 31, 2011
Description	Level 1		Level 2		Level 3		Total
Money market fund	$	41,266	$	—	$	—	$	41,266
Government-sponsored agencies		—		9,044		—		9,044
Commercial paper		—		12,541		—		12,541
Corporate debt securities		—		32,494		—		32,494
Total assets	$	41,266	$	54,079	$	—	$	95,345
Convertible debt from related party	$	—	$	—	$	10,472	$	10,472
Total liabilities	$	—	$	—	$	10,472	$	10,472

Change in fair market value of the Company's liabilities

The following table shows the change in fair market value of the Company’s liabilities during the nine months ended September 30, 2012 (in thousands):

	Fair Market Value
Convertible debt from related party
Balance as of December 31, 2011	$	10,472
Change in fair market value prior to conversion		794
Balance upon conversion		11,266
Balance as of September 30, 2012	$	—