Short-Term Investments (Tables)

3 Months Ended

Mar. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Short-term investments available-for-sale

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

	March 31, 2019
			Unrealized
	Cost		Gains		Losses		Fair Value
Commercial paper	$	18,829	$	—	$	—	$	18,829
Corporate bonds	17,271		9		(1)		17,279
Asset-backed securities	15,605		4		—		15,609
U.S. government securities	23,348		4		—		23,352
Short-term investments	$	75,053	$	17	$	(1)	$	75,069

	December 31, 2018
			Unrealized
	Cost		Gains		Losses		Fair Value
Commercial paper	$	27,898	$	—	$	—	$	27,898
Corporate bonds	28,043		—		(31)		28,012
Asset-backed securities	17,074		—		(19)		17,055
U.S. government securities	17,959		—		(2)		17,957
Short-term investments	$	90,974	$	—	$	(52)	$	90,922