Fair Value Assumptions, Average Projected Growth Rate

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Fair Value Assumptions, Discount Rate For Assets Based Fees

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Fair Value Assumptions, Market Participant Tax Rate

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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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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Amount of impairment loss resulting from write-down of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit to fair value.

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Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

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Goodwill and Acquired Client Relationships - Additional Information (Details) - USD ($)	3 Months Ended			9 Months Ended	12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill
Goodwill impairment				$ 0
Acquired Client Relationships
Estimated Future Amortization Expense of Finite-Lived Intangibles
Impairment of indefinite-lived intangibles			$ 35,000,000.0
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
Estimated Future Amortization Expense of Finite-Lived Intangibles
Impairment of indefinite-lived intangibles			$ 16,100,000
Carrying value of indefinite-lived intangibles	$ 0	$ 0	0	$ 0		$ 0
Acquired Client Relationships \| Parent Company
Estimated Future Amortization Expense of Finite-Lived Intangibles
Impairment of indefinite-lived intangibles			31,200,000
Acquired Client Relationships \| Parent Company \| Closure Of Certain Retail Investment Products
Estimated Future Amortization Expense of Finite-Lived Intangibles
Impairment of indefinite-lived intangibles			16,100,000
Acquired Client Relationships
Goodwill
Intangible amortization expense					$ 69,800,000	93,400,000
Estimated Future Amortization Expense of Finite-Lived Intangibles
Intangible future amortization expense in 2021					30,000,000
Intangible future amortization expense in 2022					30,000,000
Intangible future amortization expense in 2023					30,000,000
Intangible future amortization expense in 2024					20,000,000
Intangible future amortization expense in 2025					10,000,000
Impairment of indefinite-lived intangibles	$ 14,000,000.0	60,300,000			70,700,000	51,100,000
Fair value assumptions, average projected growth rate	(14.00%)
Fair value assumptions, discount rate for asset based fees	15.00%
Fair value assumptions, market participant tax rate	25.00%
Carrying value of indefinite-lived intangibles			$ 972,200,000		909,000,000.0	972,200,000	$ 1,006,300,000
Acquired Client Relationships \| Intangible Amortization and Impairments
Goodwill
Intangible amortization expense					$ 55,300,000	$ 93,400,000	$ 114,400,000
Acquired Client Relationships \| Closure Of Certain Retail Investment Products
Estimated Future Amortization Expense of Finite-Lived Intangibles
Impairment of indefinite-lived intangibles	$ 10,900,000
Acquired Client Relationships \| Parent Company
Estimated Future Amortization Expense of Finite-Lived Intangibles
Impairment of indefinite-lived intangibles	12,500,000	$ 32,800,000
Acquired Client Relationships \| Parent Company \| Closure Of Certain Retail Investment Products
Estimated Future Amortization Expense of Finite-Lived Intangibles
Impairment of indefinite-lived intangibles	$ 7,400,000