Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2020

Fair Value Measurements [Abstract]

Fair Value, by Balance Sheet Grouping [Table Text Block]

	Assets and Liabilities at Fair Value as of March 31, 2020
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets
Cash and cash equivalents	$	55,592	$	—	$	—	$	55,592
Short-term investments	193,545		—		—		193,545
Total cash and cash equivalents and investments	$	249,137	$	—	$	—	$	249,137

	Assets and Liabilities at Fair Value as of December 31, 2019
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets
Cash and cash equivalents	$	36,112	$	—	$	—	$	36,112
Short-term investments	235,547		—		—		235,547
Total cash and cash equivalents and investments	$	271,659	$	—	$	—	$	271,659