Cash and Cash Equivalents and Investments (Tables)

3 Months Ended

Mar. 31, 2020

Cash and Cash Equivalents and Investments [Abstract]

Schedule of Cash, Cash Equivalents and Short-term Investments [Table Text Block]

	As of March 31, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(in thousands)
Cash and cash equivalents	$	55,592	$	—	$	—	$	55,592
Securities maturing within one year:
U.S. treasury securities	192,685		860				193,545
Total short-term investments	$	192,685	$	860	$	—	$	193,545
Total cash and cash equivalents and investments	$	248,277	$	860	$	—	$	249,137
	As of December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
			(in thousands)
Cash and cash equivalents	$	36,112	$	—	$	—	$	36,112
Securities maturing within one year:
U.S. treasury securities	235,463		94		(10)		235,547
Total short-term investments	$	235,463	$	94	$	(10)	$	235,547
Total cash and cash equivalents and investments	$	271,575	$	94	$	(10)	$	271,659