Short-term Investments (Tables)

3 Months Ended

Mar. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Summary of short-term investments

Short-term investments as of December 31, 2019 consisted of the following (in thousands):

			Gross
	Amortized		Unrealized		Estimated
	Cost		Losses		Fair Value
Municipal bonds and notes	$	2,986	$	—	$	2,986
Zero coupon bonds		33,919		—		33,919
Corporate bonds		19,509		(3)		19,506
Certificates of deposit		518		—		518
Total short-term investments	$	56,932	$	(3)	$	56,929

Short-term investments as of March 31, 2020 consisted of the following (in thousands):

			Gross
	Amortized		Unrealized		Estimated
	Cost		Gains (Losses)		Fair Value
Zero coupon bonds	$	26,857	$	6	$	26,863
Corporate bonds		2,451		(2)		2,449
Certificates of deposit		518		—		518
Total short-term investments	$	29,826	$	4	$	29,830