Investments (Tables)

9 Months Ended

Sep. 30, 2021

Investments

Schedule of available-for-sale investments at fair value

	December 31, 2020
			Gross		Gross		Estimated
			Unrealized		Unrealized		Fair
(In thousands)	Cost		(Losses)		Gains		Value
Short-term investments – commercial paper	$	3,499	$	—	$	—	$	3,499
Short-term investments – US treasury bills		1,000		—		—		1,000
Total short-term investments	$	4,499	$	—	$	—	$	4,499