Fair Value - Schedule of Fair Value of Cash Equivalents, Short-term Investments and Long-term Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	$ 165,725	$ 2,056
Recurring Basis \| Cash Equivalents
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	152,822
Cash equivalents, Unrealized Losses	(3)
Cash equivalents, Fair Value	152,819
Recurring Basis \| Cash Equivalents \| Money Market Fund \| Level 1
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	66,596
Cash equivalents, Fair Value	66,596
Recurring Basis \| Cash Equivalents \| Commercial Paper \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	70,392
Cash equivalents, Unrealized Losses	(3)
Cash equivalents, Fair Value	70,389
Recurring Basis \| Cash Equivalents \| U.S. Government Debt and Agency Securities \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	835
Cash equivalents, Fair Value	835
Recurring Basis \| Cash Equivalents \| U.S. Treasury Bills \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	14,999
Cash equivalents, Fair Value	14,999
Recurring Basis \| Short-term Investments
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	60,539
Investments, Unrealized Gains	9
Investments, Unrealized Losses	(1)
Investments, Fair Value	60,547
Recurring Basis \| Short-term Investments \| Commercial Paper \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	30,393
Investments, Unrealized Gains	2
Investments, Unrealized Losses	(1)
Investments, Fair Value	30,394
Recurring Basis \| Short-term Investments \| U.S. Government Debt and Agency Securities \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	29,220
Investments, Unrealized Gains	7
Investments, Fair Value	29,227
Recurring Basis \| Short-term Investments \| Corporate Bonds \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	926
Investments, Fair Value	926
Recurring Basis \| Long-term Investments
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	33,654
Investments, Unrealized Gains	11
Investments, Unrealized Losses	(9)
Investments, Fair Value	33,656
Recurring Basis \| Long-term Investments \| U.S. Government Debt and Agency Securities \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	32,634
Investments, Unrealized Gains	11
Investments, Unrealized Losses	(9)
Investments, Fair Value	32,636
Recurring Basis \| Long-term Investments \| U.S. Treasury Bills \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	1,020
Investments, Fair Value	$ 1,020

Cash and cash equivalents accumulated gross unrealized loss before tax.

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on 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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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on 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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Amortized cost 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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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

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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), classified as noncurrent.

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Amount 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. Excludes cash and cash equivalents within disposal group and discontinued operation.

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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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