Fair Value Measurements and Marketable Securities

The Company's marketable securities are classified as “available-for-sale.” The Company includes these investments in current assets and carries them at fair value. Unrealized gains and losses on available-for-sale securities are included in accumulated other comprehensive loss on the condensed consolidated balance sheets. The amortized cost of debt securities is adjusted for the amortization of premiums and accretion of discounts to maturity. Such amortization is included in interest income in the condensed consolidated statements of operations. Gains and losses on securities sold are recorded based on the specific identification method and are included in interest and other income, net in the condensed consolidated statements of operations. The Company records all investment purchases and sales based on the trade date.

Management assesses whether declines in the fair value of marketable securities are other than temporary. If the decline is judged to be other than temporary, the cost basis of the individual security is written down to fair value and the amount of the write down is included in the statement of operations. In determining whether a decline is other than temporary, management considers various factors including the length of time and the extent to which the market value has been less than cost, the financial condition and near-term prospects of the issuer and the Company's intent and ability to retain its investment in the issuer for a period of time sufficient to allow for any anticipated recovery in market value. To date, the Company has not recorded any impairment charges on marketable securities related to other-than-temporary declines in market value.

The fair value of the Company's financial assets and liabilities is determined by using three levels of input which are defined as follows:

Level 1 - Quoted prices in active markets for identical assets or liabilities. At March 31, 2015, the Company's Level 1 assets were comprised of money market funds.

Level 2 - Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The Company's short-term investments primarily utilize broker quotes in markets with infrequent transactions for valuation of these securities. At March 31, 2015, the Company's Level 2 assets were comprised of FDIC insured certificates of deposit.

Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. At March 31, 2015, the Company did not hold any Level 3 assets.

The Company utilizes the market approach to measure fair value for its financial assets and liabilities. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities.

The following is a summary of the Company's available-for-sale securities at March 31, 2015 and December 31, 2014, respectively (in thousands):



As of March 31, 2015	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Certificates of deposit – FDIC insured	$	11,960	$	—	$	(2	)	$	11,958
Total marketable securities	$	11,960	$	—	$	(2	)	$	11,958



As of December 31, 2014	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Certificates of deposit – FDIC insured	$	11,960	$	—	$	(8	)	$	11,952
Total marketable securities	$	11,960	$	—	$	(8	)	$	11,952

At March 31, 2015, the Company's marketable securities had the following remaining contractual maturities (in thousands):



	Amortized Cost		Estimated Fair Value
Less than one year	$	11,960	$	11,958

The following table sets forth the basis of fair value measurements for the Company's cash equivalents and available-for-sale securities as of March 31, 2015 and December 31, 2014 (in thousands):



	March 31, 2015
	Level 1		Level 2		Level 3		Fair value
Cash equivalents:
Money market funds	$	376,585	$	—	$	—	$	376,585
Marketable securities:
Certificates of deposit - FDIC insured	—		11,958		—		11,958
	$	376,585	$	11,958	$	—	$	388,543



	December 31, 2014
	Level 1		Level 2		Level 3		Fair value
Cash equivalents:
Money market funds	$	373,119	$	—	$	—	$	373,119
Marketable securities:
Certificates of deposit - FDIC insured	—		11,952		—		11,952
	$	373,119	$	11,952	$	—	$	385,071

There were no transfers between levels of the fair value hierarchy during the three months ended March 31, 2015.