v3.25.2
Fair Value Measurements (Assets and Liabilities Measured on a Recurring Basis) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Mar. 31, 2025
Dec. 31, 2024
Mar. 31, 2024
Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                
Investments, Fair Value Disclosure $ 833.7 $ 744.7 $ 833.7 $ 744.7   $ 742.0   $ 740.8
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]                
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                
Investments, Fair Value Disclosure 45.5   45.5     43.8    
Foreign currency forward contracts receivable 0.0   0.0     0.0    
Loans Receivable, Fair Value Disclosure 0.0   0.0     0.0    
Deferred compensation plan assets 0.0   0.0     0.0    
Mortgage banking derivative asset 0.0   0.0     0.0    
Total assets at fair value 45.5   45.5     43.8    
Foreign currency forward contracts payable 0.0   0.0     0.0    
Deferred compensation plan liabilities 0.0   0.0     0.0    
Business Combination, Contingent Consideration, Liability 0.0   0.0     0.0    
Mortgage banking derivative liabilities 0.0   0.0     0.0    
Total liabilities at fair value 0.0   0.0     0.0    
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]                
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                
Investments, Fair Value Disclosure 0.0   0.0     0.0    
Foreign currency forward contracts receivable 6.3   6.3     4.9    
Loans Receivable, Fair Value Disclosure 1,228.6   1,228.6     770.7    
Deferred compensation plan assets 674.9   674.9     664.0    
Mortgage banking derivative asset 0.0   0.0     0.0    
Total assets at fair value 1,909.8   1,909.8     1,439.6    
Foreign currency forward contracts payable 8.5   8.5     13.9    
Deferred compensation plan liabilities 658.5   658.5     658.4    
Business Combination, Contingent Consideration, Liability 0.0   0.0     0.0    
Mortgage banking derivative liabilities 0.0   0.0     0.0    
Total liabilities at fair value 667.0   667.0     672.3    
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]                
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                
Derivative Assets (Liabilities), at Fair Value, Net 19.9 31.7 19.9 31.7 $ 16.7 93.8 $ 18.9 10.3
Investments, Fair Value Disclosure 293.1 367.8 293.1 367.8 311.0 330.3 369.7 367.3
Foreign currency forward contracts receivable 0.0   0.0     0.0    
Loans Receivable, Fair Value Disclosure 0.0   0.0     0.0    
Deferred compensation plan assets 0.0   0.0     0.0    
Mortgage banking derivative asset 54.2   54.2     161.1    
Total assets at fair value 347.3   347.3     491.4    
Foreign currency forward contracts payable 0.0   0.0     0.0    
Deferred compensation plan liabilities 0.0   0.0     0.0    
Business Combination, Contingent Consideration, Liability 19.1 53.7 19.1 53.7 $ 37.5 35.8 $ 46.7 $ 57.5
Mortgage banking derivative liabilities 34.3   34.3     67.3    
Total liabilities at fair value 53.4   53.4     $ 103.1    
Investments [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]                
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings (25.3) (9.3) (45.2) (10.4)        
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) 1.4 (0.1) 2.1 (0.3)        
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases 6.0 2.3 6.0 2.8        
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements 0.0 0.0 (0.1) 0.0        
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 0.0 5.2 0.0 8.4        
Derivative [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]                
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings 9.7 19.5 17.0 28.2        
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) 0.0 0.0 0.0        
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases 34.9 22.3 64.9 46.1        
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements (41.4) (29.0) (155.8) (52.9)        
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 0.0 0.0 0.0        
Earn-out Liabilities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]                
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings (7.4) (2.1) (3.5) (12.6)        
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) 0.3 0.0 0.4 0.0        
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases 0.2 11.0 0.2 11.0        
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements (12.0) (1.7) (12.1) (2.0)        
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 $ 0.5 $ (0.2) $ (1.7) $ (0.2)