v3.26.1
Corporate Investments and Funds Held For Clients - Cash and Cash Equivalents and Investments (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Jun. 30, 2025
Corporate Investments and Funds Held for Clients [Line Items]      
Cash and cash equivalents, amortized cost $ 198.0 $ 370.0  
Funds held for clients cash and cash equivalents, amortized cost 2,631.0 4,762.5  
Total investments, amortized cost 3,204.1 5,506.2  
Gross unrealized gains 0.1 0.8  
Gross unrealized losses (0.2)    
Cash and cash equivalents, fair value 198.0 370.0 $ 532.2
Funds held for clients cash and cash equivalents, fair value 2,631.0 4,762.5  
Total investments, fair value 3,204.1 5,507.0  
Available-for-sale Securities [Member] | U.S. Treasury Securities [Member]      
Corporate Investments and Funds Held for Clients [Line Items]      
Amortized cost [1] 300.2 298.7  
Gross unrealized gains [1] 0.1 0.7  
Gross unrealized losses [1] (0.2)    
Fair value [1] 300.1 299.4  
Available-for-sale Securities [Member] | Certificates of Deposit [Member]      
Corporate Investments and Funds Held for Clients [Line Items]      
Amortized cost [1] 75.0 75.0  
Gross unrealized gains [1]   0.1  
Fair value [1] $ 75.0 $ 75.1  
[1] All available-for-sale securities were included within the funds held for clients.