Other Comprehensive Income (Loss) - Schedule of changes in accumulated other comprehensive income (loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Balance at the beginning of the period			$ (102.8)
Other comprehensive income before reclassifications
Before tax amount			14.6	$ (15.9)
Tax benefit			(0.2)	0.6
After tax amount			14.4	(15.3)
Amounts reclassified from accumulated other comprehensive loss (1)			2.7	3.0
Total changes in other comprehensive (loss) income, net of tax	$ (45.1)	$ (32.1)	17.1	(12.3)
Balance at the end of the period	(85.8)		(85.8)
Pension and Postretirement
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Balance at the beginning of the period			(69.6)	(62.3)
Other comprehensive income before reclassifications
Before tax amount			0.0	0.0
Tax benefit			0.0	0.0
After tax amount			0.0	0.0
Amounts reclassified from accumulated other comprehensive loss (1)			1.8	2.5
Total changes in other comprehensive (loss) income, net of tax			1.8	2.5
Balance at the end of the period	(67.8)	(65.8)	(67.8)	(65.8)
Currency Translation
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Balance at the beginning of the period			(21.1)	(64.7)
Other comprehensive income before reclassifications
Before tax amount			14.0	(12.3)
Tax benefit			0.0	0.0
After tax amount			14.0	(12.3)
Amounts reclassified from accumulated other comprehensive loss (1)			0.0	0.0
Total changes in other comprehensive (loss) income, net of tax			14.0	(12.3)
Balance at the end of the period	(7.1)	(77.0)	(7.1)	(77.0)
Net Unrealized Gain (Loss) on Derivative Instruments
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Balance at the beginning of the period			(12.1)	(13.6)
Other comprehensive income before reclassifications
Before tax amount			0.5	(3.0)
Tax benefit			(0.2)	0.6
After tax amount			0.3	(2.4)
Amounts reclassified from accumulated other comprehensive loss (1)			0.9	0.5
Total changes in other comprehensive (loss) income, net of tax			1.2	(1.9)
Balance at the end of the period	(10.9)	(15.5)	(10.9)	(15.5)
Total Attributable to Hillenbrand, Inc.
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Balance at the beginning of the period			(102.8)	(84.2)
Other comprehensive income before reclassifications
Before tax amount			14.5	(15.3)
Tax benefit			(0.2)	0.6
After tax amount			14.3	(14.7)
Amounts reclassified from accumulated other comprehensive loss (1)			2.7	3.0
Total changes in other comprehensive (loss) income, net of tax			17.0	(11.7)
Balance at the end of the period	$ (85.8)	(158.3)	(85.8)	(158.3)
Noncontrolling Interests
Other comprehensive income before reclassifications
Before tax amount			0.1	(0.6)
Tax benefit			0.0	0.0
After tax amount			0.1	(0.6)
Amounts reclassified from accumulated other comprehensive loss (1)			0.0	0.0
Total changes in other comprehensive (loss) income, net of tax		$ (0.5)	$ 0.1	$ (0.6)