v3.26.1
Borrowings - Additional Information (Details)
€ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Jun. 30, 2026
EUR (€)
Dec. 31, 2025
USD ($)
Jun. 30, 2021
USD ($)
May 31, 2021
USD ($)
Mar. 31, 2014
USD ($)
Mar. 31, 2013
USD ($)
Debt Instrument [Line Items]                    
Interest $ 38,200,000 $ 28,000,000.0 $ 76,800,000 $ 55,800,000            
Borrowings 3,026,100,000   3,026,100,000     $ 3,025,100,000        
Fair value of collateralized loan obligation assets 10,900,000,000   $ 10,900,000,000     11,000,000,000.0        
Senior Notes                    
Debt Instrument [Line Items]                    
Debt redemption price percentage (percent)     100.00%              
CLO Borrowings                    
Debt Instrument [Line Items]                    
Interest 3,800,000 4,000,000.0 $ 8,000,000.0 7,800,000            
Borrowings           350,100,000        
CLO Financing Facility                    
Debt Instrument [Line Items]                    
Outstanding borrowings 346,100,000   346,100,000   € 283.1          
CLO Financing Facility | Euro Member Countries, Euro                    
Debt Instrument [Line Items]                    
Outstanding borrowings $ 323,100,000   $ 323,100,000              
5.650% Senior Notes Due 9/15/2048                    
Debt Instrument [Line Items]                    
Interest rate (percent) 5.65%   5.65%   5.65%          
Borrowings $ 350,000,000.0   $ 350,000,000.0     350,000,000.0        
5.650% Senior Notes Due 9/15/2048 | Senior Notes                    
Debt Instrument [Line Items]                    
Borrowings 350,000,000.0   350,000,000.0              
Fair value of debt $ 339,300,000   $ 339,300,000     347,500,000        
5.650% Senior Notes Due 9/15/2048 | Treasury rate | Senior Notes                    
Debt Instrument [Line Items]                    
Discount rate, spread on variable rate     0.40%              
5.625% Senior Notes Due 3/30/2043                    
Debt Instrument [Line Items]                    
Interest rate (percent) 5.625%   5.625%   5.625%          
Borrowings $ 600,000,000.0   $ 600,000,000.0     600,000,000.0        
5.625% Senior Notes Due 3/30/2043 | Senior Notes                    
Debt Instrument [Line Items]                    
Borrowings 600,000,000.0   600,000,000.0           $ 200,000,000.0 $ 400,000,000.0
Fair value of debt $ 584,400,000   $ 584,400,000     600,700,000        
5.625% Senior Notes Due 3/30/2043 | Treasury rate | Senior Notes                    
Debt Instrument [Line Items]                    
Discount rate, spread on variable rate     0.40%              
5.050% Senior Notes Due 9/19/2035                    
Debt Instrument [Line Items]                    
Interest rate (percent) 5.05%   5.05%   5.05%          
Borrowings $ 800,000,000.0   $ 800,000,000.0     800,000,000.0        
5.050% Senior Notes Due 9/19/2035 | Senior Notes                    
Debt Instrument [Line Items]                    
Interest rate (percent) 5.05%   5.05%   5.05%          
Borrowings $ 800,000,000.0   $ 800,000,000.0              
Fair value of debt $ 777,800,000   $ 777,800,000     800,900,000        
5.050% Senior Notes Due 9/19/2035 | Treasury rate | Senior Notes                    
Debt Instrument [Line Items]                    
Discount rate, spread on variable rate     0.20%              
3.500% Senior Notes Due 9/19/2029                    
Debt Instrument [Line Items]                    
Interest rate (percent) 3.50%   3.50%   3.50%          
Borrowings $ 425,000,000.0   $ 425,000,000.0     425,000,000.0        
3.500% Senior Notes Due 9/19/2029 | Senior Notes                    
Debt Instrument [Line Items]                    
Interest rate (percent) 3.50%   3.50%   3.50%          
Borrowings $ 425,000,000.0   $ 425,000,000.0              
Fair value of debt 412,400,000   $ 412,400,000     417,800,000        
3.500% Senior Notes Due 9/19/2029 | Treasury rate | Senior Notes                    
Debt Instrument [Line Items]                    
Discount rate, spread on variable rate     0.30%              
4.625% Subordinated Notes Due 5/15/2061                    
Debt Instrument [Line Items]                    
Interest $ 5,900,000 5,900,000 $ 11,800,000 11,800,000            
Interest rate (percent) 4.625%   4.625%   4.625%     4.625%    
Borrowings $ 500,000,000.0   $ 500,000,000.0     500,000,000.0 $ 65,000,000.0 $ 435,000,000.0    
Period from tax redemption event that debt may be redeemed (in days)     120 days              
Fair value of debt 326,200,000   $ 326,200,000     342,000,000.0        
Revolving Credit Facility                    
Debt Instrument [Line Items]                    
Borrowing capacity 1,000,000,000.0   1,000,000,000.0              
Management fee-earning assets $ 156,900,000,000   $ 156,900,000,000              
Covenant, liquidity ratio required, maximum 4.0   4.0   4.0          
Interest rate under credit facility (percent) 4.75%   4.75%   4.75%          
Borrowings under credit facilities $ 0 0 $ 0 0            
Outstanding borrowings 0   0              
Fair value of debt 41,500,000   $ 41,500,000     $ 63,000,000.0        
Revolving Credit Facility | Base rate                    
Debt Instrument [Line Items]                    
Margin spread on interest rate (percent)     0.50%              
Revolving Credit Facility | SOFR                    
Debt Instrument [Line Items]                    
Margin spread on interest rate (percent)     0.10%              
Revolving Credit Facility | SOFR | Maximum                    
Debt Instrument [Line Items]                    
Margin spread on interest rate (percent)     1.50%              
Revolving Credit Facility | Global Credit Revolving Credit Facility                    
Debt Instrument [Line Items]                    
Borrowings under credit facilities 0 $ 0 $ 0 $ 0            
Outstanding borrowings 0   $ 0              
Revolving Credit Facility | Global Credit Revolving Credit Facility | Base rate                    
Debt Instrument [Line Items]                    
Margin spread on interest rate (percent)     1.00%              
Revolving Credit Facility | Global Credit Revolving Credit Facility | SOFR                    
Debt Instrument [Line Items]                    
Margin spread on interest rate (percent)     2.00%              
Revolving Credit Facility | Global Credit Revolving Credit Facility Maturing in 2027                    
Debt Instrument [Line Items]                    
Borrowing capacity 300,000,000   $ 300,000,000              
Revolving Credit Facility | Global Credit Revolving Credit Facility Maturing in 2026                    
Debt Instrument [Line Items]                    
Borrowing capacity $ 200,000,000   $ 200,000,000