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Goodwill and Acquired Client Relationships - Additional Information (Details) - Acquired Client Relationships - USD ($) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020 | Dec. 31, 2020
Intangible Assets |  |  |  |  |
Amortization and impairment expenses of intangible assets |  |  | $ 16,400,000 |  |
Estimated Future Amortization Expense of Finite-Lived Intangibles |  |  |  |  |
Finite-lived intangible, future amortization expense, remainder of fiscal year | $ 15,000,000 |  | 15,000,000 |  |
Finite-lived intangible, future amortization expense in year one | 30,000,000 |  | 30,000,000 |  |
Finite-lived intangible, future amortization expense in year two | 30,000,000 |  | 30,000,000 |  |
Finite-lived intangible, future amortization expense in year three | 15,000,000 |  | 15,000,000 |  |
Finite-lived intangible, future amortization expense in year four | 10,000,000 |  | 10,000,000 |  |
Finite-lived intangible, future amortization expense in year five | 10,000,000 |  | 10,000,000 |  |
Intangible impairments |  | $ 60,300,000 | 0 |  |
Indefinite-lived acquired client relationships | 913,000,000.0 | 0 | 913,000,000.0 | $ 0 | $ 909,000,000.0
Intangible amortization and impairments |  |  |  |  |
Intangible Assets |  |  |  |  |
Amortization and impairment expenses of intangible assets | $ 8,900,000 | 20,600,000 | $ 16,400,000 | $ 41,200,000 |
Controlling Interest |  |  |  |  |
Estimated Future Amortization Expense of Finite-Lived Intangibles |  |  |  |  |
Intangible impairments |  | $ 32,800,000 |  |  |

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