Consolidated and Nonconsolidated Investment Entities - Fair Value Hierarchy (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Transfers, Net	$ 0.0
Assets measured on recurring basis
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	4,183.0	$ 3,751.0
NAV	2,802.0	2,469.0
Liabilities	1,234.0	880.0
Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
NAV	0.0	0.0
Level 1 | Assets measured on recurring basis
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	88.0	171.0
Liabilities	0.0	0.0
Level 2 | Assets measured on recurring basis
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	1,293.0	1,111.0
Liabilities	1,234.0	880.0
Level 3 | Assets measured on recurring basis
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0.0	0.0
Liabilities	0.0	0.0
Cash and cash equivalents | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	88.0	171.0
NAV	0.0	0.0
Cash and cash equivalents | Level 1 | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	88.0	171.0
Cash and cash equivalents | Level 2 | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0.0	0.0
Cash and cash equivalents | Level 3 | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0.0	0.0
Corporate loans, at fair value using the fair value option | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	1,293.0	1,111.0
NAV	0.0	0.0
Corporate loans, at fair value using the fair value option | Level 1 | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0.0	0.0
Corporate loans, at fair value using the fair value option | Level 2 | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	1,293.0	1,111.0
Corporate loans, at fair value using the fair value option | Level 3 | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0.0	0.0
Limited Partnerships/Corporations, at fair value | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	2,802.0	2,469.0
NAV	2,802.0	2,469.0
Limited Partnerships/Corporations, at fair value | Level 1 | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0.0	0.0
Limited Partnerships/Corporations, at fair value | Level 2 | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0.0	0.0
Limited Partnerships/Corporations, at fair value | Level 3 | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0.0	0.0
CLO notes, at fair value using the fair value option | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
NAV	0.0	0.0
Liabilities	1,234.0	880.0
CLO notes, at fair value using the fair value option | Level 1 | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities	0.0	0.0
CLO notes, at fair value using the fair value option | Level 2 | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities	1,234.0	880.0
CLO notes, at fair value using the fair value option | Level 3 | Assets measured on recurring basis | VIEs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities	$ 0.0	$ 0.0