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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Intangible Assets - Narrative (Details) - USD ($) $ in Millions			12 Months Ended
	Nov. 18, 2019	Jul. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-lived Intangible Assets
Amortization expense for finite-lived intangible assets			$ 7.5	$ 6.2	$ 0.6
Expected aggregate annual amortization expense for finite-lived intangible assets in 2020			8.6
Expected aggregate annual amortization expense for finite-lived intangible assets in 2021			8.6
Expected aggregate annual amortization expense for finite-lived intangible assets in 2022			8.6
Expected aggregate annual amortization expense for finite-lived intangible assets in 2023			8.6
Expected aggregate annual amortization expense for finite-lived intangible assets in 2024			8.6
Rights to Manage Fund Assets
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets			335.2	204.1
Rights to Manage Fund Assets \| Hermes
Indefinite-lived Intangible Assets [Line Items]
Increase of indefinite-lived intangible assets		$ 198.5	65.8
Trade Name
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets			$ 52.0	$ 50.1
Trade Name \| Hermes
Indefinite-lived Intangible Assets [Line Items]
Increase of indefinite-lived intangible assets		$ 49.9
PNC Capital Advisors LLC \| Rights to Manage Fund Assets
Indefinite-lived Intangible Assets [Line Items]
Increase of indefinite-lived intangible assets	$ 58.0