Investments, Summary of Investments (Details) $ in Thousands		6 Months Ended
		Jun. 30, 2022 USD ($) Company	Dec. 31, 2021 USD ($)
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		8
Number of public companies in which there is an equity ownership interest of less than 20% | Company		3
Available-for-sale Securities with Maturity of One Year or Less [Abstract]
Amortized cost		$ 1,032,687	$ 612,557
Gross unrealized gains		39	792
Gross unrealized losses		(7,088)	(345)
Estimated fair value		1,025,638	613,004
Available-for-sale Securities with Maturity of More Than One Year [Abstract]
Amortized cost		514,406	638,615
Gross unrealized gains		64	471
Gross unrealized losses		(16,841)	(3,966)
Estimated fair value		497,629	635,120
Available-for-sale Securities [Abstract]
Amortized cost		1,547,093	1,251,172
Gross unrealized gains		103	1,263
Gross unrealized losses		(23,929)	(4,311)
Estimated fair value		1,523,267	1,248,124
Equity Securities [Abstract]
Amortized cost		35,012	27,512
Gross unrealized gains		17,257	23,852
Gross unrealized losses		(7,159)	(837)
Estimated fair value		45,110	50,527
Available-for-sale and Equity Securities [Abstract]
Amortized cost		1,582,105	1,278,684
Gross unrealized gains		17,360	25,115
Gross unrealized losses		(31,088)	(5,148)
Estimated fair value		1,568,377	1,298,651
Corporate Debt Securities [Member]
Available-for-sale Securities with Maturity of One Year or Less [Abstract]
Amortized cost	[1]	481,866	383,870
Gross unrealized gains		4	728
Gross unrealized losses		(3,749)	(226)
Estimated fair value		478,121	384,372
Available-for-sale Securities with Maturity of More Than One Year [Abstract]
Amortized cost		294,276	382,000
Gross unrealized gains		1	331
Gross unrealized losses		(11,542)	(2,644)
Estimated fair value		282,735	379,687
Debt Securities Issued by U.S. Government Agencies [Member]
Available-for-sale Securities with Maturity of One Year or Less [Abstract]
Amortized cost		55,207	48,493
Gross unrealized gains		0	19
Gross unrealized losses		(927)	(18)
Estimated fair value		54,280	48,494
Available-for-sale Securities with Maturity of More Than One Year [Abstract]
Amortized cost		35,545	72,935
Gross unrealized gains		0	0
Gross unrealized losses		(1,451)	(561)
Estimated fair value		34,094	72,374
Debt Securities Issued by the U.S. Treasury [Member]
Available-for-sale Securities with Maturity of One Year or Less [Abstract]
Amortized cost	[1]	340,480	45,424
Gross unrealized gains		34	0
Gross unrealized losses		(1,829)	(64)
Estimated fair value		338,685	45,360
Available-for-sale Securities with Maturity of More Than One Year [Abstract]
Amortized cost		158,476	137,635
Gross unrealized gains		61	139
Gross unrealized losses		(3,100)	(500)
Estimated fair value		155,437	137,274
Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member]
Available-for-sale Securities with Maturity of One Year or Less [Abstract]
Amortized cost		148,750	134,770
Gross unrealized gains		1	45
Gross unrealized losses		(493)	(37)
Estimated fair value		148,258	134,778
Available-for-sale Securities with Maturity of More Than One Year [Abstract]
Amortized cost		26,109	39,909
Gross unrealized gains		2	1
Gross unrealized losses		(748)	(224)
Estimated fair value		25,363	39,686
Other Municipal Debt Securities [Member]
Available-for-sale Securities with Maturity of One Year or Less [Abstract]
Amortized cost		6,384
Gross unrealized gains		0
Gross unrealized losses		(90)
Estimated fair value		6,294
Available-for-sale Securities with Maturity of More Than One Year [Abstract]
Amortized cost			6,136
Gross unrealized gains			0
Gross unrealized losses			(37)
Estimated fair value			6,099
Publicly Traded Equity Securities [Member]
Equity Securities [Abstract]
Amortized cost	[2]	11,897	11,897
Gross unrealized gains		0	7,145
Gross unrealized losses		(7,159)	(837)
Estimated fair value		4,738	18,205
Available-for-sale and Equity Securities [Abstract]
Unrealized loss on equity investment		(13,500)
Privately Held Equity Securities [Member]
Equity Securities [Abstract]
Amortized cost	[3]	23,115	15,615
Gross unrealized gains		17,257	16,707
Gross unrealized losses		0	0
Estimated fair value		$ 40,372	$ 32,322

[1] Includes investments classified as cash equivalents on our condensed consolidated balance sheet.

[2] Our equity securities included in other current assets consisted of our investments in publicly traded companies. We recognize publicly traded equity securities at fair value. In the six months ended June 30, 2022, we recognized a $13.5 million unrealized loss in our condensed consolidated statement of operations related to a decrease in the fair value of our investments in publicly traded companies.

[3] Our equity securities included in deposits and other assets consisted of our investments in privately held companies. We recognize our private company 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.