Investments, Summary of Investments (Details) $ in Thousands		9 Months Ended
		Sep. 30, 2023 USD ($) Company	Dec. 31, 2022 USD ($)
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		$ 1,346,830	$ 1,223,522
Gross unrealized gains		14	64
Gross unrealized losses		(9,190)	(12,018)
Estimated fair value		1,337,654	1,211,568
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		553,704	525,314
Gross unrealized gains		236	130
Gross unrealized losses		(7,082)	(15,621)
Estimated fair value		546,858	509,823
Available-for-sale Debt Securities [Abstract]
Amortized cost		1,900,534	1,748,836
Gross unrealized gains		250	194
Gross unrealized losses		(16,272)	(27,639)
Estimated fair value		1,884,512	1,721,391
Equity Securities [Abstract]
Amortized cost		35,012	35,012
Gross unrealized gains		23,749	17,257
Gross unrealized losses		(9,208)	(1,358)
Estimated fair value		49,553	50,911
Available-for-sale Debt and Equity Securities [Abstract]
Amortized cost		1,935,546	1,783,848
Gross unrealized gains		23,999	17,451
Gross unrealized losses		(25,480)	(28,997)
Estimated fair value		1,934,065	1,772,302
Corporate Debt Securities [Member]
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract]
Amortized cost	[1]	535,408	513,790
Gross unrealized gains		13	23
Gross unrealized losses		(4,492)	(4,365)
Estimated fair value		530,929	509,448
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		195,674	227,631
Gross unrealized gains		183	14
Gross unrealized losses		(3,160)	(10,143)
Estimated fair value		192,697	217,502
Debt Securities Issued by U.S. Government Agencies [Member]
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract]
Amortized cost		267,503	133,585
Gross unrealized gains		0	0
Gross unrealized losses		(1,429)	(1,829)
Estimated fair value		266,074	131,756
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		56,365	34,339
Gross unrealized gains		0	0
Gross unrealized losses		(507)	(1,040)
Estimated fair value		55,858	33,299
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]	520,013	512,655
Gross unrealized gains		1	23
Gross unrealized losses		(3,027)	(5,124)
Estimated fair value		516,987	507,554
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		297,501	245,030
Gross unrealized gains		0	0
Gross unrealized losses		(3,364)	(4,109)
Estimated fair value		294,137	240,921
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		23,906	57,484
Gross unrealized gains		0	18
Gross unrealized losses		(242)	(686)
Estimated fair value		23,664	56,816
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		4,164	18,314
Gross unrealized gains		53	116
Gross unrealized losses		(51)	(329)
Estimated fair value		4,166	18,101
Other Municipal Debt Securities [Member]
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract]
Amortized cost			6,008
Gross unrealized gains			0
Gross unrealized losses			(14)
Estimated fair value			5,994
Publicly Traded Equity Securities [Member]
Equity Securities [Abstract]
Amortized cost	[2]	11,897	11,897
Gross unrealized gains		(1,252)	0
Gross unrealized losses		(4,083)	(1,358)
Estimated fair value		6,562	10,539
Available-for-sale Debt and Equity Securities [Abstract]
Unrealized loss on equity securities		(4,000)
Privately Held Equity Securities [Member]
Equity Securities [Abstract]
Amortized cost	[3]	23,115	23,115
Gross unrealized gains		25,001	17,257
Gross unrealized losses		(5,125)	0
Estimated fair value		42,991	$ 40,372
Available-for-sale Debt and Equity Securities [Abstract]
Unrealized gain on equity securities		$ 2,600

[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 nine months ended September 30, 2023, we recognized a $4.0 million unrealized loss in our condensed consolidated statements of operations related to a decrease 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 nine months ended September 30, 2023, we recorded a net gain of $2.6 million in our condensed consolidated statements of operations related to changes in the fair value of our investments in privately held companies.