v3.25.2
Borrowings - Schedule of Components of Interest and Other Debt Expenses (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
2025 Notes        
Debt Instrument [Line Items]        
Coupon interest $ 0.0 $ 2.6 $ 4.2 $ 7.9
Amortization of financing costs and discount 0.0 0.3 0.5 0.9
Effect of interest rate swap 0.0 0.0 0.0 0.0
Total interest expense $ 0.0 $ 2.9 $ 4.7 $ 8.8
Coupon interest rate (net of effect of interest rate swaps) (as a percent) 3.50% 3.50% 3.50% 3.50%
2027 Notes        
Debt Instrument [Line Items]        
Coupon interest $ 2.4 $ 2.4 $ 7.1 $ 7.1
Amortization of financing costs and discount 0.2 0.2 0.7 0.7
Effect of interest rate swap 3.2 4.0 10.1 12.3
Total interest expense $ 5.8 $ 6.6 $ 17.9 $ 20.1
Coupon interest rate (net of effect of interest rate swaps) (as a percent) 6.28% 7.213% 6.458% 7.262%
2029 Notes        
Debt Instrument [Line Items]        
Coupon interest $ 5.3 $ 5.3 $ 16.0 $ 16.0
Amortization of financing costs and discount 0.3 0.3 0.9 1.0
Effect of interest rate swap 0.3 1.1 1.4 3.4
Total interest expense $ 5.9 $ 6.7 $ 18.3 $ 20.4
Coupon interest rate (net of effect of interest rate swaps) (as a percent) 7.45% 8.44% 7.65% 8.469%
2030 Notes        
Debt Instrument [Line Items]        
Coupon interest $ 4.8   $ 6.6  
Amortization of financing costs and discount 0.2   0.3  
Effect of interest rate swap 0.2   0.2  
Total interest expense $ 5.2   $ 7.1  
Coupon interest rate (net of effect of interest rate swaps) (as a percent) 6.515%   6.514%