Significant Accounting Policies - Schedule of Per Share Data (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net income from continuing operations	$ 47.7	$ 52.9	$ 46.2	$ 42.2	$ 58.0	$ 85.9	$ 33.3	$ 29.4	$ 189.0	$ 206.6	$ 91.7
Less: Non-controlling interest income	0.1	(0.3)	0.1	0.1	0.1	0.0	0.0	0.0	0.0	0.1	0.0
Less: Dividends on preferred stock	5.8	5.8	5.8	5.8	5.8	5.8	5.8	5.8	23.2	23.2	7.3
Net income from continuing operations attributable to Rexnord common stockholders									165.8	183.3	84.4
Net income from continuing operations attributable to Rexnord common stockholders									189.0	206.5	84.4
Loss from discontinued operations	(0.4)	(27.8)	(83.7)	(42.8)	(119.9)	(4.3)	(3.5)	(2.9)	(154.7)	(130.6)	(17.6)
Net income (loss) attributable to Rexnord common stockholders	$ 41.4	$ 19.6	$ (43.4)	$ (6.5)	$ (67.8)	$ 75.8	$ 24.0	$ 20.7	11.1	52.7	66.8
Plus: Dividends on preferred stock									23.2	23.2	0.0
Net income attributable to Rexnord common stockholders									$ 34.3	$ 75.9	$ 66.8
Denominator:
Weighted-average common shares outstanding, basic (in shares)									104,640	103,889	102,753
Effect of dilutive common shares equivalents (in shares)									2,710	2,110	2,031
Preferred stock under the if-converted method (in shares)									15,979	15,985	0
Diluted (in shares)									123,329	121,984	104,784