Investments, Summary of Investments (Details) $ in Thousands		3 Months Ended
		Mar. 31, 2024 USD ($) Company	Dec. 31, 2023 USD ($)
Ownership Interests in Private and Public Companies [Abstract]
Number of private companies in which there is an equity ownership interest of less than 20% | Company		7
Number of public companies in which there is an equity ownership interest of less than 20% | Company		3
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract]
Amortized cost		$ 1,307,024	$ 1,316,219
Gross unrealized gains		178	415
Gross unrealized losses		(3,848)	(5,238)
Estimated fair value		1,303,354	1,311,396
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		569,655	651,628
Gross unrealized gains		672	3,063
Gross unrealized losses		(2,166)	(1,197)
Estimated fair value		568,161	653,494
Available-for-sale Debt Securities [Abstract]
Amortized cost		1,876,679	1,967,847
Gross unrealized gains		850	3,478
Gross unrealized losses		(6,014)	(6,435)
Estimated fair value		1,871,515	1,964,890
Equity Securities [Abstract]
Amortized cost		35,012	35,012
Gross unrealized gains		25,320	25,237
Gross unrealized losses		(8,881)	(10,957)
Estimated fair value		51,451	49,292
Available-for-sale Debt and Equity Securities [Abstract]
Amortized cost		1,911,691	2,002,859
Gross unrealized gains		26,170	28,715
Gross unrealized losses		(14,895)	(17,392)
Estimated fair value		1,922,966	2,014,182
Corporate Debt Securities [Member]
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract]
Amortized cost	[1]	529,593	559,967
Gross unrealized gains		87	157
Gross unrealized losses		(1,990)	(2,625)
Estimated fair value		527,690	557,499
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		248,548	243,151
Gross unrealized gains		405	1,270
Gross unrealized losses		(890)	(692)
Estimated fair value		248,063	243,729
Debt Securities Issued by U.S. Government Agencies [Member]
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract]
Amortized cost		179,632	224,711
Gross unrealized gains		24	64
Gross unrealized losses		(409)	(611)
Estimated fair value		179,247	224,164
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		115,152	110,138
Gross unrealized gains		134	547
Gross unrealized losses		(187)	(21)
Estimated fair value		115,099	110,664
Debt Securities Issued by the U.S. Treasury [Member]
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract]
Amortized cost	[1]	582,782	513,784
Gross unrealized gains		38	152
Gross unrealized losses		(1,372)	(1,889)
Estimated fair value		581,448	512,047
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		204,535	294,873
Gross unrealized gains		133	1,239
Gross unrealized losses		(1,086)	(480)
Estimated fair value		203,582	295,632
Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member]
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract]
Amortized cost		15,017	17,757
Gross unrealized gains		29	42
Gross unrealized losses		(77)	(113)
Estimated fair value		14,969	17,686
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		1,420	3,466
Gross unrealized gains		0	7
Gross unrealized losses		(3)	(4)
Estimated fair value		1,417	3,469
Publicly Traded Equity Securities [Member]
Equity Securities [Abstract]
Amortized cost	[2]	11,897	11,897
Gross unrealized gains		319	236
Gross unrealized losses		(3,756)	(5,832)
Estimated fair value		8,460	6,301
Available-for-sale Debt and Equity Securities [Abstract]
Unrealized gain on equity securities		2,200
Privately Held Equity Securities [Member]
Equity Securities [Abstract]
Amortized cost	[3]	23,115	23,115
Gross unrealized gains		25,001	25,001
Gross unrealized losses		(5,125)	(5,125)
Estimated fair value		42,991	$ 42,991
Available-for-sale Debt and Equity Securities [Abstract]
Unrealized gain on equity securities		$ 0

[1] Includes investments classified as cash equivalents in our condensed consolidated balance sheets.

[2] Our publicly traded equity securities are included in other current assets. We recognize publicly traded equity securities at fair value. In the three months ended March 31, 2024, we recorded a $2.2 million net unrealized gain in our condensed consolidated statements of operations related to changes in the fair value of our investments in publicly traded companies.

[3] Our privately held equity securities are included in deposits and other assets. We recognize our privately held equity securities at cost minus impairments, plus or minus changes resulting from observable price changes in orderly transactions for the identical or similar investment of the same issuer, which are Level 3 inputs. In the three months ended March 31, 2024, there were no changes in the fair value of our investments in privately held companies.