Fair Value Measurements (Schedule of Nonrecurring Fair Value Measurements) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended	13 Months Ended
	Sep. 30, 2025	Sep. 30, 2025	Mar. 31, 2026
Long Lived Assets Held-for-sale [Line Items]
Plant and equipment, net	$ 25,337.8	$ 25,337.8	$ 26,693.7
Project Exit Costs
Long Lived Assets Held-for-sale [Line Items]
Impairment of property and equipment			2,500.0
Fair Value, Nonrecurring | Project Exit Costs
Long Lived Assets Held-for-sale [Line Items]
Assets held for sale			454.7
Plant and equipment, net			6.9
Fair Value, Nonrecurring | Project Exit Costs | Level 3
Long Lived Assets Held-for-sale [Line Items]
Assets held for sale			454.7
Plant and equipment, net			$ 6.9
Fair Value, Nonrecurring | Project Exit Costs | Assets held for sale
Long Lived Assets Held-for-sale [Line Items]
Impairment of property and equipment	$ 350.6
Fair Value, Nonrecurring | Project Exit Costs | Plant and equipment, net
Long Lived Assets Held-for-sale [Line Items]
Impairment of property and equipment		$ 2,100.0