Financial Instruments (Details) $ in Thousands	9 Months Ended
Sep. 30, 2022 USD ($) position	Dec. 31, 2021 USD ($)
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	$ 483,893	$ 842,224
Gross Unrealized Gain		1,342
Gross Unrealized Loss	(19,285)	(3,629)
Estimated Fair Value	464,608	839,937
Proceeds from investments sold	214,700
Realized gain	500
Other than temporary impairment	$ 0
Number of investments, unrealized loss position \| position	64
Amortized Cost
Less than or equal to one year	$ 234,061
Greater than one year but less than five years	249,336
Total	483,397
Fair Value
Less than or equal to one year	227,890
Greater than or equal to one year but less than five years	236,222
Total	464,112
Money market deposits
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	496	10,041
Estimated Fair Value	496	10,041
U.S. Treasury securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	392,949	689,640
Gross Unrealized Gain		1,081
Gross Unrealized Loss	(14,841)	(2,624)
Estimated Fair Value	378,108	688,097
Corporate bonds and notes
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	24,098	52,729
Gross Unrealized Loss	(724)	(392)
Estimated Fair Value	23,374	52,337
Municipal securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	66,350	89,814
Gross Unrealized Gain		261
Gross Unrealized Loss	(3,720)	(613)
Estimated Fair Value	62,630	89,462
Available-for-sale securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Gross Unrealized Loss	(19,300)
Unrealized loss position	464,100
Cash equivalents
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Estimated Fair Value	496	10,041
Short-term investments
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Estimated Fair Value	$ 464,112	$ 829,896

Amount of cash, cash equivalents, restricted cash and investment in marketable securities.

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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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