Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Changes in accumulated other comprehensive income (loss) by component
Balance	$ 1,457.4	$ 1,662.9	$ 1,108.0
Other comprehensive income (loss) before reclassifications
Before tax amount	(25.2)	42.4	10.2
Tax benefit (expense)	(1.9)	2.9	(1.5)
After tax amount	(27.1)	45.3	8.7
Amounts reclassified from accumulated other comprehensive income	(5.9)	5.1	(0.3)
Net current period other comprehensive income (loss)	(33.0)	50.4	8.4
Balance	1,424.2	1,457.4	1,662.9
Reclassification out of Accumulated Other Comprehensive Income
Other comprehensive income (loss) before reclassifications
Amounts reclassified from accumulated other comprehensive income	(5.9)	5.1	(0.3)
Total Attributable to Hillenbrand, Inc.
Changes in accumulated other comprehensive income (loss) by component
Balance		(147.1)	(155.6)
Other comprehensive income (loss) before reclassifications
Before tax amount			10.3
Tax benefit (expense)			(1.5)
After tax amount			8.8
Amounts reclassified from accumulated other comprehensive income			(0.3)
Net current period other comprehensive income (loss)			8.5
Balance			(147.1)
Pension and Postretirement
Changes in accumulated other comprehensive income (loss) by component
Balance	(15.6)	(34.5)	(32.8)
Other comprehensive income (loss) before reclassifications
Before tax amount	8.3	(9.4)	0.2
Tax benefit (expense)	(2.5)	3.0	(0.6)
After tax amount	5.8	(6.4)	(0.4)
Amounts reclassified from accumulated other comprehensive income	(4.0)	25.3	(1.3)
Net current period other comprehensive income (loss)	1.8	18.9	(1.7)
Balance	(13.8)	(15.6)	(34.5)
Currency Translation (1)
Changes in accumulated other comprehensive income (loss) by component
Balance	(55.4)	(107.1)	(113.7)
Other comprehensive income (loss) before reclassifications
Before tax amount	9.1	51.7	6.6
Tax benefit (expense)	0.0	0.0	0.0
After tax amount	9.1	51.7	6.6
Amounts reclassified from accumulated other comprehensive income	(5.6)	0.0	0.0
Net current period other comprehensive income (loss)	3.5	51.7	6.6
Balance	(51.9)	(55.4)	(107.1)
Net Unrealized (Loss) Gain on Derivative Instruments
Changes in accumulated other comprehensive income (loss) by component
Balance	(25.6)	(5.5)	(9.1)
Other comprehensive income (loss) before reclassifications
Before tax amount	(41.1)	0.2	3.5
Tax benefit (expense)	0.6	(0.1)	(0.9)
After tax amount	(40.5)	0.1	2.6
Amounts reclassified from accumulated other comprehensive income	3.7	(20.2)	1.0
Net current period other comprehensive income (loss)	(36.8)	(20.1)	3.6
Balance	(62.4)	(25.6)	(5.5)
Noncontrolling Interests
Changes in accumulated other comprehensive income (loss) by component
Balance	34.4	32.6	25.1
Other comprehensive income (loss) before reclassifications
Before tax amount	(1.5)	(0.1)	(0.1)
Tax benefit (expense)	0.0	0.0	0.0
After tax amount	(1.5)	(0.1)	(0.1)
Amounts reclassified from accumulated other comprehensive income	0.0	0.0	0.0
Net current period other comprehensive income (loss)	(1.5)	(0.1)	(0.1)
Balance	37.5	34.4	32.6
Accumulated Other Comprehensive Loss
Changes in accumulated other comprehensive income (loss) by component
Balance	(96.6)	(147.1)	(155.6)
Other comprehensive income (loss) before reclassifications
Before tax amount	(23.7)	42.5
Tax benefit (expense)	(1.9)	2.9
After tax amount	(25.6)	45.4
Amounts reclassified from accumulated other comprehensive income	(5.9)	5.1
Net current period other comprehensive income (loss)	(31.5)	50.5
Balance	$ (128.1)	$ (96.6)	$ (147.1)