Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2016

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, 2016 and December 31, 2015 (in thousands):



	As of June 30, 2016
	Level 1		Level 2		Level 3		Total
Assets
Cash and cash equivalents:
Cash	$	3,303	$	—	$	—	$	3,303
Money market funds (1)	114,750		—		—		114,750
Domestic corporate commercial paper (2)	—		2,501		—		2,501
Total	$	118,053	$	2,501	$	—	$	120,554
Marketable Securities
Domestic corporate debt securities (2)	$	—	$	108,860	$	—	108,860
Domestic corporate commercial paper (2)	—		84,377		—		84,377
Asset-backed securities (2)	—		87,065		—		87,065
Total	$	—	$	280,302	$	—	$	280,302



	As of December 31, 2015
	Level 1		Level 2		Level 3		Total
Assets
Cash and cash equivalents:
Cash	$	2,934	$	—	$	—	$	2,934
Money market funds (1)	83,257		—		—		83,257
Domestic corporate commercial paper (2)	—		39,984		—		39,984
Government-sponsored enterprise debt securities (2)	—		15,996		—		15,996
Domestic corporate debt securities (2)	—		10,007		—		10,007
Asset-backed securities (2)	—		7,500		—		7,500
Total	$	86,191	$	73,487	$	—	$	159,678
Marketable Securities
Domestic corporate debt securities (2)	$	—	$	173,035	$	—	173,035
Domestic corporate commercial paper (2)	—		84,158		—		84,158
Asset-backed securities (2)	—		56,468		—		56,468
Total	$	—	$	313,661	$	—	$	313,661

(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.