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, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Balance at the beginning of the period				$ (81.2)
Other comprehensive income before reclassifications
Before tax amount				21.8	$ (0.4)
Tax expense				(0.2)	(4.7)
After tax amount				21.6	(5.1)
Amounts reclassified from accumulated other comprehensive income(1)	[1]			1.1	2.1
Total changes in other comprehensive income (loss), net of tax		$ 15.9	$ 13.1	22.7	(3.0)
Balance at the end of the period		(58.5)		(58.5)
Pension and Postretirement
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Balance at the beginning of the period				(45.3)	(67.5)
Other comprehensive income before reclassifications
Before tax amount				0.0	11.0
Tax expense				0.0	(4.0)
After tax amount				0.0	7.0
Amounts reclassified from accumulated other comprehensive income(1)	[1]			1.4	1.9
Total changes in other comprehensive income (loss), net of tax				1.4	8.9
Balance at the end of the period		(43.9)	(58.6)	(43.9)	(58.6)
Currency Translation
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Balance at the beginning of the period				(36.9)	(61.6)
Other comprehensive income before reclassifications
Before tax amount				21.0	(13.6)
Tax expense				0.0	0.0
After tax amount				21.0	(13.6)
Amounts reclassified from accumulated other comprehensive income(1)	[1]			0.0	0.0
Total changes in other comprehensive income (loss), net of tax				21.0	(13.6)
Balance at the end of the period		(15.9)	(75.2)	(15.9)	(75.2)
Net Unrealized Gain (Loss) on Derivative Instruments
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Balance at the beginning of the period				1.0	(0.7)
Other comprehensive income before reclassifications
Before tax amount				0.8	2.0
Tax expense				(0.2)	(0.7)
After tax amount				0.6	1.3
Amounts reclassified from accumulated other comprehensive income(1)	[1]			(0.3)	0.2
Total changes in other comprehensive income (loss), net of tax				0.3	1.5
Balance at the end of the period		1.3	0.8	1.3	0.8
Total Attributable to Hillenbrand, Inc.
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Balance at the beginning of the period				(81.2)	(129.8)
Other comprehensive income before reclassifications
Before tax amount				21.8	(0.6)
Tax expense				(0.2)	(4.7)
After tax amount				21.6	(5.3)
Amounts reclassified from accumulated other comprehensive income(1)	[1]			1.1	2.1
Total changes in other comprehensive income (loss), net of tax				22.7	(3.2)
Balance at the end of the period		$ (58.5)	$ (133.0)	(58.5)	(133.0)
Noncontrolling Interests
Other comprehensive income before reclassifications
Before tax amount				0.0	0.2
Tax expense				0.0	0.0
After tax amount				0.0	0.2
Amounts reclassified from accumulated other comprehensive income(1)	[1]			0.0	0.0
Total changes in other comprehensive income (loss), net of tax				$ 0.0	$ 0.2

[1] Amounts are net of tax.