Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2017

Summary of financial instruments measured at fair value on a recurring basis

The following table summarizes the financial instruments measured at fair value on a recurring basis in the accompanying condensed consolidated balance sheets as of June 30, 2017 and December 31, 2016 (in thousands):



	As of June 30, 2017
	Level 1		Level 2		Level 3		Total
Assets
Cash and cash equivalents:
Cash	$	98,201	$	—	$	—	$	98,201
Money market funds (1)	30,573		—		—		30,573
Domestic corporate debt securities (2)	—		6,336		—		6,336
Total	$	128,774	$	6,336	$	—	$	135,110
Marketable Securities
Domestic corporate debt securities (2)	$	—	$	34,909	$	—	$	34,909
Domestic corporate commercial paper (2)	—		44,697		—		44,697
Total	$	—	$	79,606	$	—	$	79,606



	As of December 31, 2016
	Level 1		Level 2		Level 3		Total
Assets
Cash and cash equivalents:
Cash	$	77,443	$	—	$	—	$	77,443
Money market funds (1)	173,631		—		—		173,631
Domestic corporate commercial paper (2)	—		5,487		—		5,487
Domestic corporate debt securities (2)	—		2,006		—		2,006
Total	$	251,074	$	7,493	$	—	$	258,567
Marketable Securities
Domestic corporate debt securities (2)	$	—	$	19,315	$	—	$	19,315
Domestic corporate commercial paper (2)	—		31,930		—		31,930
Asset-backed securities (2)	—		22,635		—		22,635
Total	$	—	$	73,880	$	—	$	73,880

(1) Fair value is based upon quoted market prices.

(2) Fair value is based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active and model-based valuation techniques for which all significant assumptions are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. Inputs are obtained from various sources, including market participants, dealers and brokers.