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Goodwill and Intangible Assets - Changes to Carrying Amount of Goodwill by Reporting Unit (Details) | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2022 USD ($) | Sep. 30, 2022 USD ($)
Goodwill [Line Items] |  |
Goodwill impairment | $ 0 |
Goodwill [Roll Forward] |  |
Beginning balance |  | $ 2,951,317,000
Foreign currency translation impact |  | (15,177,000)
Ending balance | 2,936,140,000 | 2,936,140,000
Goodwill, accumulated impairment losses | 0 | 0
Research |  |
Goodwill [Roll Forward] |  |
Beginning balance |  | 2,670,934,000
Foreign currency translation impact |  | (12,751,000)
Ending balance | 2,658,183,000 | 2,658,183,000
Conferences |  |
Goodwill [Roll Forward] |  |
Beginning balance |  | 184,021,000
Foreign currency translation impact |  | (148,000)
Ending balance | 183,873,000 | 183,873,000
Consulting |  |
Goodwill [Roll Forward] |  |
Beginning balance |  | 96,362,000
Foreign currency translation impact |  | (2,278,000)
Ending balance | $ 94,084,000 | $ 94,084,000

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