Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value Measurements
Marketable Securities	$ 686,946	$ 944,231
Recurring \| Estimate of Fair Value Measurement
Fair Value Measurements
Marketable Securities	686,946	944,231
Investments in Other Companies	15,402	21,380
Cash and Cash Equivalents	148,277	102,984
Total Assets Measured at Fair Value	850,625	1,068,595
Recurring \| Estimate of Fair Value Measurement \| Bonds and bond funds
Fair Value Measurements
Marketable Securities	677,074	624,254
Recurring \| Estimate of Fair Value Measurement \| Commercial Paper
Fair Value Measurements
Marketable Securities	9,872	319,977
Recurring \| Level 1
Fair Value Measurements
Investments in Other Companies	2,925	7,200
Cash and Cash Equivalents	148,277	102,984
Total Assets Measured at Fair Value	151,202	110,184
Recurring \| Level 2
Fair Value Measurements
Marketable Securities	686,946	944,231
Total Assets Measured at Fair Value	686,946	944,231
Recurring \| Level 2 \| Bonds and bond funds
Fair Value Measurements
Marketable Securities	677,074	624,254
Recurring \| Level 2 \| Commercial Paper
Fair Value Measurements
Marketable Securities	9,872	319,977
Recurring \| Level 3
Fair Value Measurements
Investments in Other Companies	12,477	14,180
Total Assets Measured at Fair Value	$ 12,477	$ 14,180

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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