v3.24.2
Customer Funds - Investment of Customer Funds (Detail) - USD ($)
$ in Millions
Jun. 30, 2024
Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]    
Money market securities, investments carried at cost and other cash equivalents, Fair Value $ 2,658.2 $ 2,800.7
Invested customer funds, Fair Value 4,961.7 4,979.0
Receivables, Fair Value 7.8 49.6
Total customer funds, Fair Value 4,969.5 5,028.6
Money market securities, investments carried at cost and other cash equivalents, Amortized Cost 2,658.2 2,800.7
Invested customer funds, Amortized Cost 5,026.1 5,043.9
Receivables, Amortized Cost 7.8 49.6
Total customer funds, Amortized Cost 5,033.9 5,093.5
Amortized Cost 2,367.9 2,243.2
Gross Unrealized Gain 3.8 8.1
Gross Unrealized Loss (68.2) (73.0)
Fair value 2,303.5 2,178.3
U.S. Government and Agencies Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 804.1 768.3
Gross Unrealized Gain 0.3 2.3
Gross Unrealized Loss (35.2) (35.1)
Fair value 769.2 735.5
Canadian and Provincial Government Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 470.4 448.7
Gross Unrealized Gain 0.8 1.3
Gross Unrealized Loss (10.1) (11.3)
Fair value 461.1 438.7
Corporate Debt Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 735.4 664.7
Gross Unrealized Gain 1.7 2.6
Gross Unrealized Loss (16.9) (19.4)
Fair value 720.2 647.9
Asset-backed Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 213.2 208.9
Gross Unrealized Gain 0.7 1.0
Gross Unrealized Loss (2.6) (3.3)
Fair value 211.3 206.6
Mortgage-backed Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 65.9 60.3
Gross Unrealized Gain 0.2 0.8
Gross Unrealized Loss (1.1) (0.7)
Fair value 65.0 60.4
Other Short-Term Investments [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 3.6 16.1
Fair value 3.6 16.1
Other Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 75.3 76.2
Gross Unrealized Gain 0.1 0.1
Gross Unrealized Loss (2.3) (3.2)
Fair value $ 73.1 $ 73.1