Significant Accounting Policies - Schedule of Per Share Data (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net income from continuing operations	$ 28.6	$ 48.4	$ 56.7	$ 48.5	$ 47.7	$ 52.9	$ 46.2	$ 42.2	$ 182.2	$ 189.0	$ 206.6
Less: Non-controlling interest income	0.1	(0.1)	0.1	0.2	0.1	(0.3)	0.1	0.1	0.3	0.0	0.1
Less: Dividends on preferred stock	0.0	2.8	5.8	5.8	5.8	5.8	5.8	5.8	14.4	23.2	23.2
Net income from continuing operations attributable to Rexnord common stockholders									167.5	165.8	183.3
Loss from discontinued operations, net of tax	0.0	0.0	0.0	(1.8)	(0.4)	(27.8)	(83.7)	(42.8)	(1.8)	(154.7)	(130.6)
Net income from continuing operations attributable to Rexnord common stockholders									181.9	189.0	206.5
Net income attributable to Rexnord common stockholders	$ 28.5	$ 45.7	$ 50.8	$ 40.7	$ 41.4	$ 19.6	$ (43.4)	$ (6.5)	165.7	11.1	52.7
Plus: Dividends on preferred stock									(14.4)	(23.2)	(23.2)
Net income attributable to Rexnord common stockholders									$ 180.1	$ 34.3	$ 75.9
Denominator:
Weighted-average common shares outstanding, basic (in shares)									111,689	104,640	103,889
Effect of dilutive common shares equivalents (in shares)									2,576	2,710	2,110
Preferred stock under the if-converted method (in shares)									9,998	15,979	15,985
Diluted (in shares)									124,263	123,329	121,984