v3.20.4
Derivative Financial Instruments and Hedging Derivatives designated as hedges and pledged collateral (Details) - USD ($)
$ in Millions
3 Months Ended
Dec. 31, 2019
Dec. 31, 2020
Sep. 30, 2020
Derivative Instruments, (Gain) Loss      
Accumulated Other Comprehensive Income, Cumulative Changes in Net Gain from Hedges, Before Tax   $ 90.7  
Cross Currency Swap Settlements and Unrealized Gains Included in AOCI   99.5 $ 99.5
Cross Currency Swap Settlements and Unrealized Gains Recognized in AOCI $ 1.4    
Collateral Already Posted   0.3 4.9
Hedging Instruments      
Derivative Instruments, (Gain) Loss      
Accumulated Other Comprehensive Income, Cumulative Changes in Net Gain from Hedges, Before Tax   90.7 90.2
Accumulated Other Comprehensive Income, Cumulative Changes in Net Gain from Hedges, Effect Net of Tax   68.3 $ 67.9
Interest Rate Swap | Hedging Instruments      
Derivative Instruments, (Gain) Loss      
Interest Rate Swap Losses to be Reclassified During Next 12 Months   $ 2.3