FAIR VALUE MEASUREMENT - Assets and Liabilities Measured At Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets:
Cash equivalents—Money market funds	$ 264,576	$ 252,650
Equity securities, at fair value	41,091	82,823
Available-for-sale debt securities	10,358
Trading securities held in a "rabbi trust"	459	399
Total assets	316,484	335,872
Liabilities:
Deferred compensation accrual "rabbi trust"	475	396
Total liabilities	475	396
Level 1
Assets:
Cash equivalents—Money market funds	264,576	252,650
Equity securities, at fair value	15	36
Available-for-sale debt securities	0
Trading securities held in a "rabbi trust"	459	399
Total assets	265,050	253,085
Liabilities:
Deferred compensation accrual "rabbi trust"	475	396
Total liabilities	475	396
Level 2
Assets:
Cash equivalents—Money market funds	0	0
Equity securities, at fair value	0	0
Available-for-sale debt securities	0
Trading securities held in a "rabbi trust"	0	0
Total assets	0	0
Liabilities:
Deferred compensation accrual "rabbi trust"	0	0
Total liabilities	0	0
Level 3
Assets:
Cash equivalents—Money market funds	0	0
Equity securities, at fair value	41,076	82,787
Available-for-sale debt securities	10,358
Trading securities held in a "rabbi trust"	0	0
Total assets	51,434	82,787
Liabilities:
Deferred compensation accrual "rabbi trust"	0	0
Total liabilities	$ 0	$ 0

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).

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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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Aggregate carrying value as of the balance sheet date of the liabilities for deferred compensation arrangements. Represents currently earned compensation under cash arrangements (such as a profit-sharing plan, rabbi trust, and employee contract--excluding equity-based arrangements) that is not actually paid until a later date.

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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 noncurrent.

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Fair value of financial and nonfinancial obligations.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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