Acquisitions, Luvata HTS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended								6 Months Ended	12 Months Ended
	Nov. 30, 2016	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2017	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Jan. 29, 2016
Business Acquisition [Line Items]
Cost related to acquisition and integration		$ 0.6	$ 1.0	$ 1.1	$ 1.6	$ 3.2	$ 7.2	$ 3.0	$ 1.4
Allocation of Purchase Price for Acquisition [Abstract]
Goodwill		173.8				165.1					$ 173.8	$ 165.1	$ 15.8
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Interest expense											25.6	17.2	11.1
Commercial and Industrial Solutions ("CIS") [Member]
Business Acquisition [Line Items]
Net sales											620.0	177.7
Operating income											25.8	7.5
Goodwill - measurement-period adjustments										$ 1.3
Allocation of Purchase Price for Acquisition [Abstract]
Goodwill		$ 158.3				150.9					$ 158.3	150.9	0.0
Modine Puxin Thermal System (Jiangsu) Co. Ltd. [Member]
Allocation of Purchase Price for Acquisition [Abstract]
Property, plant and equipment														$ 1.5
Acquisition-related Costs [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Amortization and depreciation expense												13.0
Interest expense												14.0
Acquisition related transaction costs						8.6						8.6
Inventory purchase accounting adjustment												4.3
Luvata HTS [Member]
Business Acquisition [Line Items]
Acquired ownership interest by the entity	100.00%	100.00%									100.00%
Purchase price allocation, net of cash acquired	$ 388.2
Cost related to acquisition and integration											$ 4.3	14.8
Allocation of Purchase Price for Acquisition [Abstract]
Cash and cash equivalents	27.4
Trade accounts receivable	86.1
Inventories	55.0
Property, plant and equipment	120.4
Intangible assets	130.2
Goodwill	151.9					$ 150.6						150.6
Other assets	39.1
Accounts payable	(73.7)
Accrued compensation and employee benefits	(24.3)
Deferred income taxes	(39.5)
Pensions	(14.3)
Other liabilities	(42.7)
Purchase price	415.6
Pro Forma Information [Abstract]
Net sales												1,881.6	1,871.9
Net earnings attributable to Modine												$ 35.8	$ 1.5
Net earnings per share attributable to Modine Shareholders [Abstract]
Basic (in dollars per share)												$ 0.72	$ 0.03
Diluted (in dollars per share)												$ 0.71	$ 0.03
Luvata HTS [Member] | Customer Relationships [Member]
Allocation of Purchase Price for Acquisition [Abstract]
Intangible assets	$ 58.4
Weighted-average useful life, intangible assets, amortization period	17 years
Luvata HTS [Member] | Trade Names [Member]
Allocation of Purchase Price for Acquisition [Abstract]
Intangible assets	$ 50.1
Weighted-average useful life, intangible assets, amortization period	20 years
Luvata HTS [Member] | Acquired Technology [Member]
Allocation of Purchase Price for Acquisition [Abstract]
Intangible assets	$ 21.7
Weighted-average useful life, intangible assets, amortization period	12 years
Luvata HTS [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Shares issued to acquire Luvata HTS (in shares)	2.2
Value of shares issued to acquire Luvata HTS	$ 24.3