Financial Instruments - Summary of Cash and Cash Equivalents, Money Market Funds and Short-term Investments by Significant Investment Category (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Adjusted Cost	$ 263,729	$ 53,568
Unrealized Gains	15	1
Unrealized Losses	(47)	(2)
Market Value	263,697	53,567
Level 1 \| Money Market Funds
Schedule Of Available For Sale Securities [Line Items]
Adjusted Cost	27,686	16,366
Market Value	27,686	16,366
Level 2 \| U.S. Treasury Securities Included in Cash and Cash Equivalents and Short-term Investments
Schedule Of Available For Sale Securities [Line Items]
Adjusted Cost	63,101	2,998
Unrealized Gains	4
Unrealized Losses	(1)
Market Value	63,104	2,998
Level 2 \| U.S. Government Agency Securities Included in Short-term Investments
Schedule Of Available For Sale Securities [Line Items]
Adjusted Cost	54,183	34,204
Unrealized Gains	10	1
Unrealized Losses		(2)
Market Value	54,193	$ 34,203
Level 2 \| Corporate Debt Securities Included in Cash and Cash Equivalents and Short-term Investments
Schedule Of Available For Sale Securities [Line Items]
Adjusted Cost	118,759
Unrealized Gains	1
Unrealized Losses	(46)
Market Value	$ 118,714

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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