Condensed Consolidating Information - Consolidating balance sheet (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018
ASSETS
Cash and cash equivalents	$ 374.0		$ 399.0	$ 58.6
Trade receivables, net	292.8		217.4
Receivables from long-term manufacturing contracts	187.3		181.1
Inventories, net	423.3		176.6
Other current assets	86.7		49.1
Total current assets	1,364.1		1,023.2
Property, plant, and equipment, net	348.7		140.3
Operating lease right-of-use assets	165.0		0.0
Intangible assets, net	1,101.3		454.9
Goodwill	1,133.5		578.0
Investment in consolidated subsidiaries	0.0
Other long-term assets	78.1		32.2
Total Assets	4,190.7		2,228.6
LIABILITIES
Trade accounts payable	297.9		236.2
Liabilities from long-term manufacturing contracts and advances	176.6		158.2
Current portion of long-term debt	46.7		0.0
Accrued compensation	78.2		73.2
Other current liabilities	205.8		121.7
Total current liabilities	805.2		589.3
Long-term debt	1,826.6		619.5
Accrued pension and postretirement healthcare	157.9		131.3
Operating lease liabilities	130.8		0.0
Deferred Income Tax Liabilities, Net	187.5		73.6
Other long-term liabilities	55.7		45.1
Total Liabilities	3,163.7		1,458.8
Hillenbrand Shareholders’ Equity	1,009.0		754.1
Stockholders' Equity Attributable to Parent [Abstract]
Noncontrolling interests	18.0		15.7
Total Shareholders’ Equity	1,027.0	$ 1,143.8	769.8	$ 770.1	$ 747.4	$ 744.1
Total Liabilities and Shareholders’ Equity	4,190.7		2,228.6
Reportable legal entities | Parent
ASSETS
Cash and cash equivalents	145.3		283.1
Intercompany receivables	0.0		0.0
Other current assets	4.6		2.5
Total current assets	149.9		285.6
Property, plant, and equipment, net	3.7		3.8
Operating lease right-of-use assets	0.7
Intangible assets, net	2.3		2.4
Investment in consolidated subsidiaries	3,947.1		2,266.4
Other long-term assets	49.9		33.8
Total Assets	4,153.6		2,592.0
LIABILITIES
Trade accounts payable	3.9		2.6
Current portion of long-term debt	45.3		0.0
Accrued compensation	3.0		6.9
Intercompany payables	1,287.9		1,167.0
Other current liabilities	26.2		19.2
Total current liabilities	1,366.3		1,195.7
Long-term debt	1,754.8		619.5
Accrued pension and postretirement healthcare	0.9		0.8
Operating lease liabilities	0.4
Deferred Income Tax Liabilities, Net	0.0		0.0
Other long-term liabilities	22.2		21.9
Total Liabilities	3,144.6		1,837.9
Hillenbrand Shareholders’ Equity	1,009.0		754.1
Stockholders' Equity Attributable to Parent [Abstract]
Total Shareholders’ Equity	1,009.0		754.1
Total Liabilities and Shareholders’ Equity	4,153.6		2,592.0
Reportable legal entities | Guarantors
ASSETS
Cash and cash equivalents	11.5		9.6
Trade receivables, net	92.3		113.6
Receivables from long-term manufacturing contracts	13.2		9.8
Inventories, net	78.2		78.2
Intercompany receivables	1,135.2		1,179.7
Other current assets	25.3		6.1
Total current assets	1,355.7		1,397.0
Property, plant, and equipment, net	60.8		61.2
Operating lease right-of-use assets	13.2
Intangible assets, net	174.3		181.4
Goodwill	170.3		225.0
Investment in consolidated subsidiaries	654.1		655.2
Other long-term assets	27.4		20.5
Total Assets	2,455.8		2,540.3
LIABILITIES
Trade accounts payable	60.4		59.0
Liabilities from long-term manufacturing contracts and advances	13.0		13.5
Accrued compensation	13.3		20.8
Intercompany payables	0.0		10.2
Other current liabilities	54.8		45.0
Total current liabilities	141.5		148.5
Accrued pension and postretirement healthcare	30.4		32.1
Operating lease liabilities	10.3
Deferred Income Tax Liabilities, Net	12.0		24.0
Other long-term liabilities	14.7		12.5
Total Liabilities	208.9		217.1
Hillenbrand Shareholders’ Equity	2,246.9		2,323.2
Stockholders' Equity Attributable to Parent [Abstract]
Total Shareholders’ Equity	2,246.9		2,323.2
Total Liabilities and Shareholders’ Equity	2,455.8		2,540.3
Reportable legal entities | Non-Guarantors
ASSETS
Cash and cash equivalents	217.2		106.3
Trade receivables, net	200.5		103.8
Receivables from long-term manufacturing contracts	174.1		171.3
Inventories, net	347.9		101.2
Intercompany receivables	149.9		0.0
Other current assets	54.8		40.1
Total current assets	1,144.4		522.7
Property, plant, and equipment, net	284.2		75.3
Operating lease right-of-use assets	151.1
Intangible assets, net	924.7		271.1
Goodwill	963.2		353.0
Investment in consolidated subsidiaries	0.0
Other long-term assets	27.7		3.1
Total Assets	3,495.3		1,225.2
LIABILITIES
Trade accounts payable	233.6		174.6
Liabilities from long-term manufacturing contracts and advances	163.6		144.7
Current portion of long-term debt	1.4		0.0
Accrued compensation	61.9		45.5
Intercompany payables	0.0		5.3
Other current liabilities	124.5		67.1
Total current liabilities	585.0		437.2
Long-term debt	71.8		0.0
Accrued pension and postretirement healthcare	126.6		98.4
Operating lease liabilities	120.1
Deferred Income Tax Liabilities, Net	200.7		64.8
Other long-term liabilities	18.8		10.7
Total Liabilities	1,123.0		611.1
Hillenbrand Shareholders’ Equity	2,354.3		598.4
Stockholders' Equity Attributable to Parent [Abstract]
Noncontrolling interests	18.0		15.7
Total Shareholders’ Equity	2,372.3		614.1
Total Liabilities and Shareholders’ Equity	3,495.3		1,225.2
Consolidation, Eliminations [Member]
ASSETS
Inventories, net	(2.8)		(2.8)
Intercompany receivables	(1,285.1)		(1,179.7)
Other current assets	2.0		0.4
Total current assets	(1,285.9)		(1,182.1)
Investment in consolidated subsidiaries	(4,601.2)		(2,921.6)
Other long-term assets	(26.9)		(25.2)
Total Assets	(5,914.0)		(4,128.9)
LIABILITIES
Trade accounts payable	0.0		0.0
Intercompany payables	(1,287.9)		(1,182.5)
Other current liabilities	0.3		(9.6)
Total current liabilities	(1,287.6)		(1,192.1)
Deferred Income Tax Liabilities, Net	(25.2)		(15.2)
Other long-term liabilities	0.0
Total Liabilities	(1,312.8)		(1,207.3)
Hillenbrand Shareholders’ Equity	(4,601.2)		(2,921.6)
Stockholders' Equity Attributable to Parent [Abstract]
Total Shareholders’ Equity	(4,601.2)		(2,921.6)
Total Liabilities and Shareholders’ Equity	$ (5,914.0)		$ (4,128.9)