Fair Value Measurements (Details) - USD ($) $ in Thousands		Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021	Apr. 30, 2021	Dec. 31, 2019
Fair Value Measurements [Abstract]
Available-for-sale securities		$ 1,964,890		$ 1,721,391
Equity securities		$ 49,292		$ 50,911
1.75% Notes [Member]
Fair Value Measurements [Abstract]
Interest rate on convertible senior notes		1.75%		1.75%
0.125% Notes [Member]
Fair Value Measurements [Abstract]
Interest rate on convertible senior notes		0.125%		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%	0.00%
Publicly Traded Equity Securities [Member]
Fair Value Measurements [Abstract]
Equity securities		$ 6,301		$ 10,539
Recurring Basis [Member]
Fair Value Measurements [Abstract]
Cash equivalents	[1]	185,424		211,655
Total		2,156,615		1,943,585
Recurring Basis [Member] | Corporate Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		801,228	[2]	726,950	[3]
Recurring Basis [Member] | Corporate Debt Securities [Member] | Cash and Cash Equivalents [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		33,000		11,000
Recurring Basis [Member] | Debt Securities Issued by U.S. Government Agencies [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities	[4]	334,828		165,055
Recurring Basis [Member] | Debt Securities Issued by the U.S. Treasury [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities	[4]	807,679		748,475
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	[4]	21,155		74,917
Recurring Basis [Member] | Other Municipal Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities	[4]			5,994
Recurring Basis [Member] | Publicly Traded Equity Securities [Member] | Other Current Assets [Member]
Fair Value Measurements [Abstract]
Equity securities	[5]	6,301		10,539
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Fair Value Measurements [Abstract]
Cash equivalents		185,424		211,655
Total		999,404		970,669
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		807,679		748,475
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
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member] | Publicly Traded Equity Securities [Member] | Other Current Assets [Member]
Fair Value Measurements [Abstract]
Equity securities		6,301		10,539
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value Measurements [Abstract]
Cash equivalents		0		0
Total		1,157,211		972,916
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | 1.75% Notes [Member]
Fair Value Measurements [Abstract]
Convertible notes		661,100
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | 0.125% Notes [Member]
Fair Value Measurements [Abstract]
Convertible notes		42,400
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | 0% Notes [Member]
Fair Value Measurements [Abstract]
Convertible notes		667,800
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		801,228		726,950
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		334,828		165,055
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		21,155		74,917
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other Municipal Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities				5,994
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Publicly Traded Equity Securities [Member] | Other Current Assets [Member]
Fair Value Measurements [Abstract]
Equity securities		$ 0		$ 0

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

[2] $33.0 million was included in cash and cash equivalents, with the difference included in short-term investments in our consolidated balance sheets.

[3] $11.0 million was included in cash and cash equivalents, with the difference included in short-term investments in our consolidated balance sheets.

[4] Included in short-term investments in our consolidated balance sheets.

[5] Included in other current assets in our consolidated balance sheets.