Basis of Presentation and Summary of Significant Accounting Policies - Carrying Amounts and Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Assets
Money market funds	$ 41,675	$ 50,731
Marketable securities – certificates of deposit	117,036	116,469
Marketable securities – equity securities	39	70
Total	158,750	167,270
Level 1
Assets
Money market funds	41,675	50,731
Marketable securities – certificates of deposit	117,036	116,469
Marketable securities – equity securities	39	70
Total	158,750	167,270
Level 2
Assets
Money market funds	0	0
Marketable securities – certificates of deposit	0	0
Marketable securities – equity securities	0	0
Total	0	0
Level 3
Assets
Money market funds	0	0
Marketable securities – certificates of deposit	0	0
Marketable securities – equity securities	0	0
Total	$ 0	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes 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.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
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