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Business Combinations - Narrative, PRA Acquisition (Details) $ / shares in Units, $ in Thousands |  | 12 Months Ended
--- | --- | ---
Jul. 01, 2021 Employee $ / shares shares | Dec. 31, 2023 USD ($) Employee | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($)
Business Acquisition [Line Items] |  |  |  |
Number of employees | Employee | 38,000 | 41,100 |  |
Integration related costs |  | $ 44,176 | $ 39,695 | $ 198,263
Total financing costs |  | 336,699 | 229,731 | 182,423
PRA Health Sciences, Inc |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Business acquisition, share price (in USD per share) | $ / shares | $ 80 |  |  |
Business acquisition, number of shares issued (in shares) | shares | 0.4125 |  |  |
Total financing costs |  | $ 16,400 | $ 17,700 | $ 86,700

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