Investments

3 Months Ended

Mar. 31, 2020

Investments, Debt and Equity Securities [Abstract]

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


	March 31, 2020
			Unrealized
	Cost		Gains		Losses		Fair Value
Short-Term:
Commercial paper	$	6,292	$	—	$	—	$	6,292

Asset-backed securities	6,100		1		(7)		6,094
U.S. government securities	47,021		201		—		47,222
Short-term investments	$	59,413	$	202	$	(7)	$	59,608
Long-Term:


U.S. government securities	6,047		92		—		6,139
Long-term investments	$	6,047	$	92	$	—	$	6,139


	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 March 31, 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 March 31, 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.