Fair Value Measurements (Fair Values of Financial Instruments Measured On Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Consensus common stock	$ 26,000	$ 58,400
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Certificates of deposit	3,753
Consensus common stock	26,044	58,421
Investment in corporate debt securities	15,469	15,586
Total assets measured at fair value	333,876	386,017
Contingent consideration	3,389	555
Total liabilities measured at fair value	3,389	555
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Certificates of deposit	3,753
Consensus common stock	26,044	58,421
Investment in corporate debt securities	15,469	15,586
Total assets measured at fair value	333,876	386,017
Contingent consideration	3,389	555
Total liabilities measured at fair value	3,389	555
Money market and other funds \| Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market and other funds	288,610	312,010
Money market and other funds \| Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market and other funds	288,610	312,010
Level 1 \| Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Certificates of deposit	0
Consensus common stock	26,044	58,421
Investment in corporate debt securities	0	0
Total assets measured at fair value	314,654	370,431
Contingent consideration	0	0
Total liabilities measured at fair value	0	0
Level 1 \| Money market and other funds \| Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market and other funds	288,610	312,010
Level 2 \| Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Certificates of deposit	3,753
Consensus common stock	0	0
Investment in corporate debt securities	0	0
Total assets measured at fair value	3,753	0
Contingent consideration	0	0
Total liabilities measured at fair value	0	0
Level 2 \| Money market and other funds \| Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market and other funds	0	0
Level 3 \| Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Certificates of deposit	0
Consensus common stock	0	0
Investment in corporate debt securities	15,469	15,586
Total assets measured at fair value	15,469	15,586
Contingent consideration	3,389	555
Total liabilities measured at fair value	3,389	555
Level 3 \| Money market and other funds \| Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market and other funds	$ 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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Amount of liability recognized arising from contingent consideration in a business combination.

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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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A savings certificate entitling the Entity (that is, bearer) to receive interest at an established maturity date, based upon a fixed interest rate. A certificate of deposit may be issued in any denomination. Certificates of deposit are generally issued by commercial banks and, therefore, insured by the FDIC (up to the prescribed limit). Certificates of deposit generally restrict holders from withdrawing funds on demand without the incurrence of penalties. Generally, only certificates of deposit with original maturities of three months or less qualify as cash equivalents. Original maturity means original maturity to the entity holding the investment. As a related example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

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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).

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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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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

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