Fair value

The fair value of our financial assets reflects our estimate of amounts that we would have received in connection with the sale of such asset in an orderly transaction between market participants at the measurement date. In connection with measuring the fair value of our assets, we seek to maximize the use of observable inputs (market data obtained from independent sources) and to minimize the use of unobservable inputs (our assumptions about how market participants would price assets). We use the following fair value hierarchy to classify assets based on the observable inputs and unobservable inputs we used to value our assets:


•	Level 1—quoted prices (unadjusted) in active markets for identical assets.


•	Level 2—quoted prices for similar assets in active markets or inputs that are observable for the asset, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument.


•	Level 3—unobservable inputs based on our assumptions used to measure assets at fair value.

For fixed income securities, we reference pricing data supplied by our custodial agent and nationally known pricing vendors, using a variety of daily data sources, largely readily-available market data and broker quotes. The prices provided by third-party pricing services are validated by reviewing their pricing methods and obtaining market values from other pricing sources.

The following tables provide our assets that are measured at fair value on a recurring basis as of June 30, 2017 and December 31, 2016 (in thousands):



Description	Balance as of June 30, 2017		Level 1		Level 2		Level 3
Assets:
Cash and money market funds	$	22,937	$	22,937	$	—	$	—
Corporate debt securities (including commercial paper)	63,622		—		63,622		—
Total	$	86,559	$	22,937	$	63,622	$	—



Description	Balance as of December 31, 2016		Level 1		Level 2		Level 3
Assets:
Cash and money market funds	$	43,930	$	43,930	$	—	$	—
Corporate debt securities (including commercial paper)	70,458		—		70,458		—
Total	$	114,388	$	43,930	$	70,458	$	—