Financial Instruments (Details) $ in Thousands	12 Months Ended
Dec. 31, 2022 USD ($) position	Dec. 31, 2021 USD ($)
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Proceeds from investments sold	$ 248,500	$ 187,600
Gross realized gains and realized losses	$ 900
Number of investments, unrealized loss position \| position	61
Less than 12 Months, Fair value	$ 35,048
12 Months or Longer, Fair value	395,746
Fair value	430,794
Less than 12 Months, Unrealized loss	(692)
12 Months or Longer, Unrealized loss	(15,411)
Unrealized loss	(16,103)
Amortized Cost
Less than or equal to one year	329,499
Greater than one year but less than five years	118,904
Total	448,403
Fair Value
Less than or equal to one year	320,708
Greater than or equal to one year but less than five years	111,593
Total	432,301
Available-for-sale securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	857,357	842,224
Gross Unrealized Gain	1	1,342
Gross Unrealized Loss	(16,103)	(3,629)
Estimated Fair Value	841,255	839,937
Gross unrealized loss	16,103	3,629
Money market deposits
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	283,358	10,041
Estimated Fair Value	283,358	10,041
Liquid demand deposits
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	125,596
Estimated Fair Value	125,596
U.S. Treasury securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	358,385	689,640
Gross Unrealized Gain		1,081
Gross Unrealized Loss	(12,328)	(2,624)
Estimated Fair Value	346,057	688,097
Less than 12 Months, Fair value	18,677
12 Months or Longer, Fair value	327,374
Fair value	346,051
Less than 12 Months, Unrealized loss	(565)
12 Months or Longer, Unrealized loss	(11,762)
Unrealized loss	(12,327)
Gross unrealized loss	12,328	2,624
Corporate bonds and notes
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	24,045	52,729
Gross Unrealized Loss	(516)	(392)
Estimated Fair Value	23,529	52,337
12 Months or Longer, Fair value	23,529
Fair value	23,529
12 Months or Longer, Unrealized loss	(516)
Unrealized loss	(516)
Gross unrealized loss	516	392
Municipal securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	65,973	89,814
Gross Unrealized Gain	1	261
Gross Unrealized Loss	(3,259)	(613)
Estimated Fair Value	62,715	89,462
Less than 12 Months, Fair value	16,371
12 Months or Longer, Fair value	44,843
Fair value	61,214
Less than 12 Months, Unrealized loss	(127)
12 Months or Longer, Unrealized loss	(3,133)
Unrealized loss	(3,260)
Gross unrealized loss	3,259	613
Cash equivalents \| Available-for-sale securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Estimated Fair Value	408,954	10,041
Short-term investments \| Available-for-sale securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Estimated Fair Value	$ 432,301	$ 829,896

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