Cash Equivalents and Investments - Tabular Disclosure - Cash Equivalents (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Money market funds
Cash equivalents:
Cash equivalents, Amortized Cost	$ 341,711	$ 98,946
Cash equivalents	341,711	98,946
U.S. Treasury obligations
Cash equivalents:
Cash equivalents, Amortized Cost	29,999	14,992
Cash equivalents	$ 29,999	$ 14,992

Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_CashEquivalentsAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant