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 |