v3.25.2
Customer Funds - Investment of Customer Funds (Detail) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]    
Money market securities, investments carried at cost and other cash equivalents, Fair Value $ 1,690.0 $ 2,650.9
Invested customer funds, Fair Value 4,233.4 4,978.2
Receivables, Fair Value 26.1 23.3
Total customer funds, Fair Value 4,259.5 5,001.5
Money market securities, investments carried at cost and other cash equivalents, Amortized Cost 1,690.0 2,650.9
Invested customer funds, Amortized Cost 4,225.9 5,003.8
Receivables, Amortized Cost 26.1 23.3
Total customer funds, Amortized Cost 4,252.0 5,027.1
Amortized Cost 2,535.9 2,352.9
Gross Unrealized Gain 27.3 14.9
Gross Unrealized Loss (19.8) (40.5)
Fair value 2,543.4 2,327.3
U.S. Government and Agencies Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 869.3 818.3
Gross Unrealized Gain 4.7 0.5
Gross Unrealized Loss (14.1) (27.1)
Fair value 859.9 791.7
Canadian and Provincial Government Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 498.8 449.2
Gross Unrealized Gain 5.9 4.6
Gross Unrealized Loss (1.9) (3.6)
Fair value 502.8 450.2
Corporate Debt Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 798.9 734.7
Gross Unrealized Gain 12.5 7.7
Gross Unrealized Loss (3.0) (7.0)
Fair value 808.4 735.4
Asset-backed Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 205.4 202.9
Gross Unrealized Gain 2.3 1.9
Gross Unrealized Loss (0.3) (0.6)
Fair value 207.4 204.2
Mortgage-backed Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 105.1 83.5
Gross Unrealized Gain 1.6 0.1
Gross Unrealized Loss (0.3) (1.3)
Fair value 106.4 82.3
Other Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 58.4 64.3
Gross Unrealized Gain 0.3 0.1
Gross Unrealized Loss (0.2) (0.9)
Fair value $ 58.5 $ 63.5