Other Comprehensive Income (Loss) - Schedule of reclassifications (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Affected Line in the Consolidated Statement of Operations:
Net revenue	$ 550.2	$ 706.9
Cost of Product and Service Sold	(366.5)	(471.9)
Tax expense	12.9	(6.4)
Total reclassifications for the period, net of tax	0.1	0.7
Amortization of Pension and Postretirement
Affected Line in the Consolidated Statement of Operations:
Total reclassifications for the period, net of tax	0.2	0.0
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Affected Line in the Consolidated Statement of Operations:
Total reclassifications for the period, net of tax	(0.1)	0.7
Reclassifications out of accumulated other comprehensive income (loss)
Affected Line in the Consolidated Statement of Operations:
Net revenue	(0.1)	0.3
Operating expenses	0.2	(0.5)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0.1	0.8
Tax expense	0.0	(0.1)
Total reclassifications for the period, net of tax	0.1	0.7
Reclassifications out of accumulated other comprehensive income (loss) \| Accumulated Defined Benefit Plans Adjustment Net Loss Recognized [Member]
Affected Line in the Consolidated Statement of Operations:
Net revenue	0.0	0.0
Operating expenses	0.2	0.0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0.2	0.0
Reclassifications out of accumulated other comprehensive income (loss) \| Accumulated Defined Benefit Plans Adjustment Prior Service Cost Recognized [Member]
Affected Line in the Consolidated Statement of Operations:
Net revenue	0.0	0.0
Operating expenses	0.0	0.0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0.0	0.0
Reclassifications out of accumulated other comprehensive income (loss) \| Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Affected Line in the Consolidated Statement of Operations:
Net revenue	(0.1)	0.3
Operating expenses	0.0	(0.5)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	$ (0.1)	$ 0.8

Hillenbrand, Inc. 10-Q