Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2013

Summary of Financial Assets, and Liabilities, Allocated into Level 1, Level 2, and Level 3 Measured on Recurring Basis

The following table sets forth the fair value of our financial assets and liabilities,allocated into Level1, Level 2, and Level 3, that was measured on a recurring basis (in thousands):

	June30, 2013
	Level1			Level2			Level3			Total
Financial Assets:
Money market funds	$	103,302	$		—	$		—	$		103,302
Corporate notes and commercial paper		—			77,004			—			77,004
U.S. government agency securities		—			45,940			—			45,940
Total financial assets	$	103,302	$		122,944	$		—	$		226,246
Financial Liabilities:
Foreign currency forward contracts	$	—	$		228	$		—	$		228

	December31, 2012
	Level1			Level2			Level3			Total
Financial Assets:
Money market funds	$	43,303	$		—	$		—	$		43,303
Corporate notes and commercial paper		—			64,425			—			64,425
U.S. government agency securities		—			19,346			—			19,346
Foreign currency forward contracts		—			51			—			51
Total financial assets	$	43,303	$		83,822	$		—	$		127,125
Financial Liabilities:
Convertible preferred stock warrant liability	$	—	$		—	$		683	$		683

Summary of Changes in Estimated Fair Value

The following table sets forth a summary of the changes in the estimated fair value of our convertible preferred stock warrants,which were measured at fair value on a recurring basis until their conversion to common stock warrants and related reclassification to additional paid-in capital (in thousands):

Balance as of December31, 2012	$	683
Recognized gain upon final remeasurement		(24	)
Reclassification of warrant liability to additional paid-in capital		(659	)
Balance as of June30, 2013	$	—

Estimated Fair Value of Convertible Preferred Stock Warrant determined Using Black-Sholes Option Pricing Model

The estimated fair value of the convertible preferred stock warrants was determined as of May 22, 2013, the date remeasurement was no longer applicable, and June 30, 2012 using the Black-Scholes option-pricing model using the following assumptions:

	May 22, 2013			June 30, 2012
Risk free interest rate		0.11 - 0.91	%		0.33–0.72	%
Estimated term equal to the remaining contractual term		1.7–3.8years			2.6 – 4.7years
Volatility		79	%		70	%
Dividend yield		—			—