v3.26.1
Supplemental balance sheet and cash flow information (intangibles) (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Amortizable intangibles [Line Items]      
Gross carrying amount $ 981.3   $ 964.1
Accumulated amortization (645.8)   (615.7)
Net carrying amount 335.5   348.4
Amortization of intangibles 30.3 $ 29.7  
Estimated future amortization expense      
Remainder of 2025 81.4    
2026 81.1    
2027 56.6    
2028 28.2    
2029 20.8    
Internal-use software [Member]      
Amortizable intangibles [Line Items]      
Gross carrying amount 560.8   543.2
Accumulated amortization (393.0)   (373.4)
Net carrying amount 167.8   169.8
Acquired intangibles $ 17.6    
Acquired intangibles, weighted-average useful life (in years) 3 years    
Customer lists/relationships [Member]      
Amortizable intangibles [Line Items]      
Gross carrying amount $ 223.1   223.1
Accumulated amortization (179.4)   (174.4)
Net carrying amount 43.7   48.7
Partner relationships [Member]      
Amortizable intangibles [Line Items]      
Gross carrying amount 75.9   76.3
Accumulated amortization (25.1)   (24.1)
Net carrying amount 50.8   52.2
Technology-based intangibles [Member]      
Amortizable intangibles [Line Items]      
Gross carrying amount 65.0   65.0
Accumulated amortization (39.3)   (37.2)
Net carrying amount 25.7   27.8
Residual commission buy-out [Member]      
Amortizable intangibles [Line Items]      
Gross carrying amount 36.0   36.0
Accumulated amortization (1.8)   0.0
Net carrying amount 34.2   36.0
Other [Member]      
Amortizable intangibles [Line Items]      
Gross carrying amount 20.5   20.5
Accumulated amortization (7.2)   (6.6)
Net carrying amount $ 13.3   $ 13.9