Investments

9 Months Ended

Sep. 30, 2020

Investments, Debt and Equity Securities [Abstract]

Our investments are classified as available-for-sale and consist of the following:


	September 30, 2020
			Unrealized
	Cost		Gains		Losses		Fair Value
Short-Term:
Commercial paper	$	13,264	$	—	$	—	$	13,264
Corporate bonds	6,580		—		(1)		6,579

U.S. government securities	36,015		74		—		36,089
Short-term investments	$	55,859	$	74	$	(1)	$	55,932


	December 31, 2019
			Unrealized
	Cost		Gains		Losses		Fair Value
Short-Term:
Commercial paper	$	14,214	$	—	$	—	$	14,214
Corporate bonds	26,194		16		(2)		26,208
Asset-backed securities	8,097		5		(1)		8,101
U.S. government securities	78,017		65		—		78,082
Short-term investments	$	126,522	$	86	$	(3)	$	126,605
Long-Term:
Corporate bonds	$	6,258	$	18	$	—	$	6,276
Long-term investments	$	6,258	$	18	$	—	$	6,276

As of September 30, 2020 and December 31, 2019, we had no investments with a contractual maturity of greater than two years. Currently, we do not intend to sell the investments and it is not more likely than not that we will be required to sell the investments before recovery of their amortized cost bases, which may be maturity. We do not consider those investments to be other-than-temporarily impaired at September 30, 2020. At the end of each reporting period, we evaluate potential credit impairment on available-for-sale securities in an unrealized loss position, based on the expected cash flows to be collected and the yield-to-maturity on those securities. Securities with a valuation allowance for expected credit losses and deemed uncollectible are permanently written-down, and a reversal out of the valuation allowance occurs.