Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Components of basic and diluted earnings per share [Abstract]
Net earnings attributable to Modine	$ 38.5	$ 15.9	$ 60.5	$ 32.9
Less: Undistributed earnings attributable to unvested shares	(0.1)	(0.1)	(0.2)	(0.3)
Net earnings available to Modine shareholders	$ 38.4	$ 15.8	$ 60.3	$ 32.6
Weighted-average shares outstanding - basic (in shares)	50.5	49.8	50.4	49.6
Effect of dilutive securities (in shares)	0.9	0.9	0.9	0.8
Weighted-average shares outstanding - diluted (in shares)	51.4	50.7	51.3	50.4
Earnings per share [Abstract]
Net earnings per share - basic (in dollars per share)	$ 0.76	$ 0.32	$ 1.19	$ 0.66
Net earnings per share - diluted (in dollars per share)	$ 0.75	$ 0.31	$ 1.18	$ 0.65
Stock Options [Member]
Antidilutive securities excluded from computation of earning per share [Abstract]
Antidilutive securities excluded from computation of earning per share (in shares)	0.4	0.3	0.4	0.3