Basis of Presentation and Summary of Significant Accounting Policies - Carrying Amounts and Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Assets
Money market funds	$ 126,985	$ 115,769
Marketable securities – certificates of deposit	66,862	67,637
Marketable securities – equity securities	69	58
Total	193,916	183,464
Level 1
Assets
Money market funds	126,985	115,769
Marketable securities – certificates of deposit	66,862	67,637
Marketable securities – equity securities	69	58
Total	193,916	183,464
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
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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).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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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
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