Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2014

Fair Value of Financial Assets and Liabilities Measured on Recurring Basis

The following table sets forth the fair value of our financial assets and liabilities, allocated into Level 1, Level 2 and Level 3, that was measured on a recurring basis (in thousands):

	December 31, 2014
	Level 1		Level 2		Level 3		Total
Financial Assets:
Money market funds	$	24,915	$	–	$	–	$	24,915
Corporate notes and commercial paper		–		226,047		–		226,047
U.S. government agency securities		–		120,169		–		120,169
Total financial assets	$	24,915	$	346,216	$	–	$	371,131

	December 31, 2013
	Level 1		Level 2		Level 3		Total
Financial Assets:
Money market funds	$	57,296	$	–	$	–	$	57,296
Corporate notes and commercial paper		–		182,472		–		182,472
U.S. government agency securities		–		75,289		–		75,289
Foreign currency forward contracts		–		372		–		372
Total financial assets	$	57,296	$	258,133	$	–	$	315,429

Change in Estimated Fair Value of Convertible Preferred Stock Warrants

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 (in thousands):

Change in Estimated Fair Value of Convertible Preferred Stock Warrants

Balance as of December 31, 2011		766
Recognized gain		(83	)
Balance as of December 31, 2012		683
Recognized gain		(24	)
Reclassification of warrant liability to additional paid-in capital		(659	)
Balance as of December 31, 2013	$	–

Black-Scholes Option-Pricing Model Assumptions to Estimate Fair Value of the Convertible Preferred Stock Warrants

The estimated fair value of the convertible preferred stock warrants outstanding through May 22, 2013, the date the remeasurement was no longer applicable, and the year ended December 31, 2012 was determined using the Black-Scholes option-pricing model using the following assumptions:

	May 22,		December 31,
	2013		2012
Risk-free interest rate	0.1 - 0.9%		0.3 - 0.6%
Estimated term equal to the remaining contractual term	1.7 - 3.8 years		2.1 - 4.2 years
Volatility		79%		82%
Dividend yield	–		–

- Definition

Tabular disclosure of liabilities, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, by class that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3). Where the quoted price in an active market for the identical liability is not available, the Level 1 input is the quoted price of an identical liability when traded as an asset.

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- Definition

Tabular disclosure of the fair value measurement of liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and gains or losses recognized in other comprehensive income (loss) and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs) by class of liability.

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