Financial Instruments (Details) $ in Thousands	6 Months Ended
Jun. 30, 2022 USD ($) position	Dec. 31, 2021 USD ($)
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	$ 603,806	$ 842,224
Gross Unrealized Gain		1,342
Gross Unrealized Loss	(16,185)	(3,629)
Estimated Fair Value	587,621	839,937
Proceeds from investments sold	191,900
Realized gain	200
Other than temporary impairment	$ 0
Number of investments, unrealized loss position \| position	70
Amortized Cost
Less than or equal to one year	$ 187,392
Greater than one year but less than five years	376,146
Total	563,538
Fair Value
Less than or equal to one year	184,947
Greater than or equal to one year but less than five years	362,406
Total	547,353
Money market deposits
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	40,268	10,041
Estimated Fair Value	40,268	10,041
U.S. Treasury securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	459,509	689,640
Gross Unrealized Gain		1,081
Gross Unrealized Loss	(12,505)	(2,624)
Estimated Fair Value	447,004	688,097
Corporate bonds and notes
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	34,280	52,729
Gross Unrealized Loss	(839)	(392)
Estimated Fair Value	33,441	52,337
Municipal securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	69,749	89,814
Gross Unrealized Gain		261
Gross Unrealized Loss	(2,841)	(613)
Estimated Fair Value	66,908	89,462
Available-for-sale securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Gross Unrealized Loss	(16,200)
Unrealized loss position	547,400
Cash equivalents
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Estimated Fair Value	40,268	10,041
Short-term investments
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Estimated Fair Value	$ 547,353	$ 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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