v3.26.1
Supplemental balance sheet and cash flow information (intangibles) (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Amortizable intangibles [Line Items]          
Gross carrying amount $ 960.8   $ 960.8   $ 964.1
Accumulated amortization (633.0)   (633.0)   (615.7)
Net carrying amount 327.8   327.8   348.4
Amortization of intangibles 30.4 $ 27.9 60.7 $ 57.6  
Estimated future amortization expense          
Remainder of 2026 60.2   60.2    
2027 90.2   90.2    
2028 66.1   66.1    
2029 29.4   29.4    
2030 20.4   20.4    
Internal-use software [Member]          
Amortizable intangibles [Line Items]          
Gross carrying amount 583.3   583.3   543.2
Accumulated amortization (412.8)   (412.8)   (373.4)
Net carrying amount 170.5   170.5   169.8
Acquired intangibles     $ 40.1    
Acquired intangibles, weighted-average useful life (in years)     3 years    
Customer lists/relationships [Member]          
Amortizable intangibles [Line Items]          
Gross carrying amount 180.1   $ 180.1   223.1
Accumulated amortization (140.9)   (140.9)   (174.4)
Net carrying amount 39.2   39.2   48.7
Partner relationships [Member]          
Amortizable intangibles [Line Items]          
Gross carrying amount 75.9   75.9   76.3
Accumulated amortization (26.5)   (26.5)   (24.1)
Net carrying amount 49.4   49.4   52.2
Technology-based intangibles [Member]          
Amortizable intangibles [Line Items]          
Gross carrying amount 65.0   65.0   65.0
Accumulated amortization (41.3)   (41.3)   (37.2)
Net carrying amount 23.7   23.7   27.8
Residual commission buy-out [Member]          
Amortizable intangibles [Line Items]          
Gross carrying amount 36.0   36.0   36.0
Accumulated amortization (3.6)   (3.6)   0.0
Net carrying amount 32.4   32.4   36.0
Other [Member]          
Amortizable intangibles [Line Items]          
Gross carrying amount 20.5   20.5   20.5
Accumulated amortization (7.9)   (7.9)   (6.6)
Net carrying amount $ 12.6   $ 12.6   $ 13.9