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Goodwill and Acquired Client Relationships - Additional Information (Details) - USD ($) | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Dec. 31, 2019 | Sep. 30, 2019 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Goodwill |  |  |  |  |
Goodwill impairment |  | $ 0 |  |  |
Intangible future amortization expense in 2022 | $ 30,000,000 |  | $ 30,000,000 |  |
Intangible future amortization expense in 2023 | 75,000,000 |  | 75,000,000 |  |
Acquired Client Relationships |  |  |  |  |
Goodwill |  |  |  |  |
Impairment of indefinite-lived intangibles | $ 35,000,000.0 |  | 0 |  |
Fair value assumptions, average projected growth rate | (9.00%) |  |  |  |
Fair value assumptions, discount rate for asset based fees | 14.50% |  |  |  |
Fair value assumptions, market participant tax rate | 25.00% |  |  |  |
Acquired Client Relationships | Closure Of Certain Retail Investment Products |  |  |  |  |
Goodwill |  |  |  |  |
Impairment of indefinite-lived intangibles | $ 16,100,000 |  |  |  |
Carrying value of indefinite-lived intangibles | 0 |  | 0 |  |
Acquired Client Relationships | Controlling interests |  |  |  |  |
Goodwill |  |  |  |  |
Impairment of indefinite-lived intangibles | 31,200,000 |  |  |  |
Acquired Client Relationships |  |  |  |  |
Goodwill |  |  |  |  |
Intangible amortization expense |  |  | 93,400,000 | $ 114,400,000 | $ 86,400,000
Intangible future amortization expense in 2020 | 60,000,000 |  | 60,000,000 |  |
Intangible future amortization expense in 2021 | 30,000,000 |  | 30,000,000 |  |
Intangible future amortization expense in 2023 | 30,000,000 |  | 30,000,000 |  |
Intangible future amortization expense in 2024 | 20,000,000 |  | 20,000,000 |  |
Impairment of indefinite-lived intangibles |  |  | 51,100,000 | 400,000 |
Carrying value of indefinite-lived intangibles | $ 972,200,000 |  | $ 972,200,000 | $ 1,006,300,000 | $ 1,028,700,000

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