Fair Value Measurements - Schedule of Cash and Available-for-sale Debt Securities' Amortized Cost, Unrealized Gains (Losses) and Fair Value by Significant Investment Category (Details) - USD ($)	Jun. 30, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	$ 159,318,000	$ 204,178,000
Amortized Cost	1,595,914,000	1,672,782,000
Unrealized Gain	32,000	66,000
Unrealized (Loss)	(6,265,000)	(11,885,000)
Fair Value	1,589,681,000	1,660,963,000
Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	132,434,000	87,719,000
Unrealized Gain	0	0
Unrealized (Loss)	0	0
Fair Value	132,434,000	87,719,000
Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	0	0
Unrealized (Loss)	0	0
Level I \| Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	25,018,000	125,450,000
Unrealized Gain	0	0
Unrealized (Loss)	0	0
Fair Value	25,018,000	125,450,000
Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	1,438,462,000	1,459,613,000
Unrealized Gain	32,000	66,000
Unrealized (Loss)	(6,265,000)	(11,885,000)
Fair Value	1,432,229,000	1,447,794,000
Level II \| Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	229,829,000	258,617,000
Unrealized Gain	0	46,000
Unrealized (Loss)	(1,768,000)	(2,621,000)
Fair Value	228,061,000	256,042,000
Level II \| U.S. treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	878,373,000	818,379,000
Unrealized Gain	31,000	20,000
Unrealized (Loss)	(4,227,000)	(9,233,000)
Fair Value	874,177,000	809,166,000
Level II \| U.S. government agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	63,663,000	25,283,000
Unrealized Gain	1,000	0
Unrealized (Loss)	(266,000)	(31,000)
Fair Value	63,398,000	25,252,000
Level II \| Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	266,597,000	357,334,000
Unrealized Gain	0	0
Unrealized (Loss)	(4,000)	0
Fair Value	266,593,000	357,334,000
Cash & Cash Equivalents \| Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets measured at fair value on a recurring basis	159,318,000	204,178,000
Cash & Cash Equivalents \| Fair Value, Recurring \| Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	127,373,000	77,164,000
Cash & Cash Equivalents \| Fair Value, Recurring \| Level I \| Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	25,018,000	124,979,000
Cash & Cash Equivalents \| Fair Value, Recurring \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	6,927,000	2,035,000
Cash & Cash Equivalents \| Fair Value, Recurring \| Level II \| Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	2,035,000
Cash & Cash Equivalents \| Fair Value, Recurring \| Level II \| U.S. treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Cash & Cash Equivalents \| Fair Value, Recurring \| Level II \| U.S. government agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Cash & Cash Equivalents \| Fair Value, Recurring \| Level II \| Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	6,927,000	0
Available-for-sale securities \| Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	1,425,302,000	1,445,759,000
Available-for-sale securities \| Fair Value, Recurring \| Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Available-for-sale securities \| Fair Value, Recurring \| Level I \| Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Available-for-sale securities \| Fair Value, Recurring \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	1,425,302,000	1,445,759,000
Available-for-sale securities \| Fair Value, Recurring \| Level II \| Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	228,061,000	254,007,000
Available-for-sale securities \| Fair Value, Recurring \| Level II \| U.S. treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	874,177,000	809,166,000
Available-for-sale securities \| Fair Value, Recurring \| Level II \| U.S. government agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	63,398,000	25,252,000
Available-for-sale securities \| Fair Value, Recurring \| Level II \| Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	259,666,000	357,334,000
Restricted Cash (Current and Non-Current) \| Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets measured at fair value on a recurring basis	5,061,000	11,026,000
Restricted Cash (Current and Non-Current) \| Fair Value, Recurring \| Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	5,061,000	10,555,000
Restricted Cash (Current and Non-Current) \| Fair Value, Recurring \| Level I \| Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	471,000
Restricted Cash (Current and Non-Current) \| Fair Value, Recurring \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Restricted Cash (Current and Non-Current) \| Fair Value, Recurring \| Level II \| Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Restricted Cash (Current and Non-Current) \| Fair Value, Recurring \| Level II \| U.S. treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Restricted Cash (Current and Non-Current) \| Fair Value, Recurring \| Level II \| U.S. government agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Restricted Cash (Current and Non-Current) \| Fair Value, Recurring \| Level II \| Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 0	$ 0

Cash And Cash Equivalents, Accumulated Gross Unrealized Gain, Before Tax

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Cash And Cash Equivalents, Accumulated Gross Unrealized Loss, Before Tax

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Cash And Cash Equivalents And Debt Securities, Available-For-Sale

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Cash And Cash Equivalents And Debt Securities, Available-For-Sale, Accumulated Gross Unrealized Gain, Before Tax

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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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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).

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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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