Pension Plans (Schedule of Allocation of Plan Assets) (Details) - Pension Plan - USD ($) $ in Millions | Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2019 |
United States | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | $ 490.1 | $ 491.7 | $ 463.5 |
United States | Fair Value, Inputs, Level 1, 2 and 3 | U.S. Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 60 | 57.8 | |
United States | Fair Value, Inputs, Level 1, 2 and 3 | International Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 3.4 | 2.4 | |
United States | Fair Value, Inputs, Level 1, 2 and 3 | U.S. Government | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 292.8 | 278.1 | |
United States | Fair Value, Inputs, Level 1, 2 and 3 | Other Government | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 18.9 | |
United States | Fair Value, Inputs, Level 1, 2 and 3 | CASH & CASH EQUIVALENTS | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 3.5 | 0 | |
United States | Fair Value, Inputs, Level 1, 2 and 3 | OTHER | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 7.3 | |
United States | Level 1 | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 63.4 | 60.2 | |
United States | Level 1 | U.S. Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 60 | 57.8 | |
United States | Level 1 | International Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 3.4 | 2.4 | |
United States | Level 1 | U.S. Government | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
United States | Level 1 | Other Government | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
United States | Level 1 | CASH & CASH EQUIVALENTS | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
United States | Level 1 | OTHER | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
United States | Level 2 | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 296.3 | 304.3 | |
United States | Level 2 | U.S. Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
United States | Level 2 | International Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
United States | Level 2 | U.S. Government | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 292.8 | 278.1 | |
United States | Level 2 | Other Government | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 18.9 | |
United States | Level 2 | CASH & CASH EQUIVALENTS | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 3.5 | 0 | |
United States | Level 2 | OTHER | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 7.3 | |
United States | Assets Measured at Net Asset Value | U.S. Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 76.8 | 77.6 | |
United States | Assets Measured at Net Asset Value | International Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 53.6 | 49.6 | |
United States | Assets Measured at Net Asset Value | Corporate | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
United States | Assets Measured at Net Asset Value | OTHER | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
International Pension Plan Assets | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 133.1 | 124.5 | $ 122.8 |
International Pension Plan Assets | Fair Value, Inputs, Level 1, 2 and 3 | U.S. Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
International Pension Plan Assets | Fair Value, Inputs, Level 1, 2 and 3 | International Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 9.9 | 9.8 | |
International Pension Plan Assets | Fair Value, Inputs, Level 1, 2 and 3 | U.S. Government | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
International Pension Plan Assets | Fair Value, Inputs, Level 1, 2 and 3 | Other Government | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 22.5 | 22.5 | |
International Pension Plan Assets | Fair Value, Inputs, Level 1, 2 and 3 | CASH & CASH EQUIVALENTS | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 2.6 | 0.4 | |
International Pension Plan Assets | Fair Value, Inputs, Level 1, 2 and 3 | OTHER | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 7 | 7.7 | |
International Pension Plan Assets | Level 1 | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
International Pension Plan Assets | Level 1 | U.S. Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
International Pension Plan Assets | Level 1 | International Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
International Pension Plan Assets | Level 1 | U.S. Government | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
International Pension Plan Assets | Level 1 | Other Government | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
International Pension Plan Assets | Level 1 | CASH & CASH EQUIVALENTS | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
International Pension Plan Assets | Level 1 | OTHER | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
International Pension Plan Assets | Level 2 | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 42 | 40.4 | |
International Pension Plan Assets | Level 2 | U.S. Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
International Pension Plan Assets | Level 2 | International Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 9.9 | 9.8 | |
International Pension Plan Assets | Level 2 | U.S. Government | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
International Pension Plan Assets | Level 2 | Other Government | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 22.5 | 22.5 | |
International Pension Plan Assets | Level 2 | CASH & CASH EQUIVALENTS | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 2.6 | 0.4 | |
International Pension Plan Assets | Level 2 | OTHER | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 7 | 7.7 | |
International Pension Plan Assets | Assets Measured at Net Asset Value | U.S. Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 0 | 0 | |
International Pension Plan Assets | Assets Measured at Net Asset Value | International Equity | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 28.3 | 21.1 | |
International Pension Plan Assets | Assets Measured at Net Asset Value | Corporate | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | 41.3 | 45.2 | |
International Pension Plan Assets | Assets Measured at Net Asset Value | OTHER | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Assets at estimated fair value | $ 21.5 | $ 17.8 | |