Fair Value Measurements (Details) - USD ($) $ in Thousands		Sep. 30, 2022		Dec. 31, 2021		Sep. 30, 2021
Fair Value Measurements [Abstract]
Available-for-sale securities		$ 1,701,033		$ 1,248,124
Equity securities		$ 47,628		$ 50,527
0.125% Notes [Member]
Fair Value Measurements [Abstract]
Interest rate on convertible senior notes		0.125%		0.125%		0.125%
0% Notes [Member]
Fair Value Measurements [Abstract]
Interest rate on convertible senior notes		0.00%		0.00%		0.00%
Publicly Traded Equity Securities [Member]
Fair Value Measurements [Abstract]
Equity securities		$ 7,256		$ 18,205
Significant Other Observable Inputs (Level 2) [Member] | 0.125% Notes [Member]
Fair Value Measurements [Abstract]
Fair value of convertible notes		498,700
Significant Other Observable Inputs (Level 2) [Member] | 0% Notes [Member]
Fair Value Measurements [Abstract]
Fair value of convertible notes		631,800
Recurring Basis [Member]
Fair Value Measurements [Abstract]
Cash equivalents	[1]	231,960		541,199
Total		1,940,249		1,807,528
Recurring Basis [Member] | Corporate Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		728,054	[2]	764,059	[3]
Recurring Basis [Member] | Corporate Debt Securities [Member] | Cash and Cash Equivalents [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		23,500
Recurring Basis [Member] | Debt Securities Issued by U.S. Government Agencies [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		130,767	[2]	120,868	[3]
Recurring Basis [Member] | Debt Securities Issued by the U.S. Treasury [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities	[3]	750,933		182,634
Recurring Basis [Member] | Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		85,315	[4]	174,464	[5]
Recurring Basis [Member] | Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member] | Cash and Cash Equivalents [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		10,000		2,300
Recurring Basis [Member] | Other Municipal Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities	[3]	5,964		6,099
Recurring Basis [Member] | Publicly Traded Equity Securities [Member] | Other Current Assets [Member]
Fair Value Measurements [Abstract]
Equity securities		7,256		18,205
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Fair Value Measurements [Abstract]
Cash equivalents		231,960		541,199
Total		990,149		727,708
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member] | Corporate Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		0		0
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member] | Debt Securities Issued by U.S. Government Agencies [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		0		0
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member] | Debt Securities Issued by the U.S. Treasury [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		750,933		182,634
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member] | Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		0		0
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member] | Other Municipal Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		0		0
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member] | Publicly Traded Equity Securities [Member]
Fair Value Measurements [Abstract]
Equity securities		7,256		3,875
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value Measurements [Abstract]
Cash equivalents		0		0
Total		950,100		1,065,490
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		728,054		764,059
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Debt Securities Issued by U.S. Government Agencies [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		130,767		120,868
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Debt Securities Issued by the U.S. Treasury [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		0		0
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		85,315		174,464
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other Municipal Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		5,964		6,099
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Publicly Traded Equity Securities [Member]
Fair Value Measurements [Abstract]
Equity securities		0		0
Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Measurements [Abstract]
Cash equivalents		0		0
Total		0		14,330
Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		0		0
Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Debt Securities Issued by U.S. Government Agencies [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		0		0
Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Debt Securities Issued by the U.S. Treasury [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		0		0
Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		0		0
Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other Municipal Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		0		0
Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Publicly Traded Equity Securities [Member]
Fair Value Measurements [Abstract]
Equity securities		$ 0		$ 14,330

[1] Included in cash and cash equivalents in our condensed consolidated balance sheet.

[2] $23.5 million was included in cash and cash equivalents in our condensed consolidated balance sheet, with the difference included in short-term investments in our condensed consolidated balance sheet.

[3] Included in short-term investments.

[4] $10.0 million was included in cash and cash equivalents in our condensed consolidated balance sheet, with the difference included in short-term investments in our condensed consolidated balance sheet.

[5] $2.3 million was included in cash and cash equivalents in our condensed consolidated balance sheet, with the difference included in short-term investments in our condensed consolidated balance sheet.