Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Schedule of financial instruments carried at fair value

The following tables set forth the Company’s financial instruments carried at fair value using the lowest level of input that is significant to each financial instrument as of June 30, 2020 and December 31, 2019 (in thousands):

	June 30, 2020
	Quoted Prices in Active Markets for Identical Items (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Money market funds	$	232,582	$	—	$	—	$	232,582
Corporate obligations	—		60,982		—		60,982
U.S. Treasury securities	—		64,054		—		64,054
Certificates of deposit	—		249		—		249
Total assets	$	232,582	$	125,285	$	—	$	357,867
Liabilities:
Warrants to purchase common stock	$	—	$	—	$	3,516	$	3,516
Total liabilities	$	—	$	—	$	3,516	$	3,516

	December 31, 2019
	Quoted Prices in Active Markets for Identical Items (Level 1)		Significant other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Money market funds	$	193,867	$	—	$	—	$	193,867
Corporate obligations	—		138,369		—		138,369
U.S. Treasury securities	—		83,819		—		83,819
Certificates of deposit	—		493		—		493
Mortgage and other asset backed securities	—		12,470		—		12,470
Total assets	$	193,867	$	235,151	$	—	$	429,018
Liabilities:
Warrants to purchase common stock	$	—	$	—	$	1,856	$	1,856
Total liabilities	$	—	$	—	$	1,856	$	1,856

Summary of changes in the fair value of the preferred and common stock warrant liability

The following table sets forth a summary of changes in the fair value of the Company’s common stock warrant liabilities, which represent a recurring measurement that is classified within Level 3 of the fair value hierarchy, wherein fair value is estimated using significant unobservable inputs (in thousands):

	Six Months Ended June 30,
	2020		2019
Beginning balance	$	1,856	$	1,491
Change in fair value	1,660		(102)
Ending balance	$	3,516	$	1,389