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 ($)	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	$ 86,864,000	$ 204,178,000
Amortized Cost	1,676,044,000	1,672,782,000
Unrealized Gain	3,078,000	66,000
Unrealized (Loss)	(1,018,000)	(11,885,000)
Fair Value	1,678,104,000	1,660,963,000
Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	1,584,820,000	1,459,613,000
Unrealized Gain	3,078,000	66,000
Unrealized (Loss)	(1,018,000)	(11,885,000)
Fair Value	1,586,880,000	1,447,794,000
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	86,864,000	204,178,000
Cash & Cash Equivalents \| Fair Value, Recurring \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	2,035,000
Available-for-sale Securities \| Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	1,586,880,000	1,445,759,000
Available-for-sale Securities \| Fair Value, Recurring \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	1,586,880,000	1,445,759,000
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	4,360,000	11,026,000
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
Corporate bonds \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	312,510,000	258,617,000
Unrealized Gain	718,000	46,000
Unrealized (Loss)	(378,000)	(2,621,000)
Fair Value	312,850,000	256,042,000
Corporate bonds \| Cash & Cash Equivalents \| Fair Value, Recurring \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	2,035,000
Corporate bonds \| Available-for-sale Securities \| Fair Value, Recurring \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	312,850,000	254,007,000
Corporate bonds \| 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
U.S. treasury securities \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	1,020,167,000	818,379,000
Unrealized Gain	2,344,000	20,000
Unrealized (Loss)	(544,000)	(9,233,000)
Fair Value	1,021,967,000	809,166,000
U.S. treasury securities \| Cash & Cash Equivalents \| Fair Value, Recurring \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
U.S. treasury securities \| Available-for-sale Securities \| Fair Value, Recurring \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	1,021,967,000	809,166,000
U.S. treasury securities \| 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
U.S. government agency securities \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	84,154,000	25,283,000
Unrealized Gain	14,000	0
Unrealized (Loss)	(96,000)	(31,000)
Fair Value	84,072,000	25,252,000
U.S. government agency securities \| Cash & Cash Equivalents \| Fair Value, Recurring \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
U.S. government agency securities \| Available-for-sale Securities \| Fair Value, Recurring \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	84,072,000	25,252,000
U.S. government agency securities \| 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
Commercial paper \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	167,989,000	357,334,000
Unrealized Gain	2,000	0
Unrealized (Loss)	0	0
Fair Value	167,991,000	357,334,000
Commercial paper \| Cash & Cash Equivalents \| Fair Value, Recurring \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Commercial paper \| Available-for-sale Securities \| Fair Value, Recurring \| Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	167,991,000	357,334,000
Commercial paper \| 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
Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	51,189,000	87,719,000
Unrealized Gain	0	0
Unrealized (Loss)	0	0
Fair Value	51,189,000	87,719,000
Cash \| Cash & Cash Equivalents \| Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	46,829,000	77,164,000
Cash \| Available-for-sale Securities \| Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Cash \| Restricted Cash (Current and Non-Current) \| Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	4,360,000	10,555,000
Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	0	0
Unrealized (Loss)	0	0
Money market funds \| Level I
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	40,035,000	125,450,000
Unrealized Gain	0	0
Unrealized (Loss)	0	0
Fair Value	40,035,000	125,450,000
Money market funds \| Cash & Cash Equivalents \| Fair Value, Recurring \| Level I
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	40,035,000	124,979,000
Money market funds \| Available-for-sale Securities \| Fair Value, Recurring \| Level I
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Money market funds \| Restricted Cash (Current and Non-Current) \| Fair Value, Recurring \| Level I
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 0	$ 471,000

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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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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