Quarterly Results of Operations (unaudited) - Schedule of Quarterly Results of Operations (Details) - USD ($) $ / shares in Units, $ 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
Effect of Fourth Quarter Events [Line Items]
Net sales	$ 547.0	$ 491.7	$ 521.3	$ 508.3	$ 537.5	$ 485.0	$ 524.8	$ 503.6	$ 2,068.3	$ 2,050.9	$ 1,851.6
Gross profit	216.5	191.7	208.2	201.6	201.8	184.3	203.2	195.5	818.0	784.8	706.5
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
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	28.6	48.4	56.7	46.7	47.3	25.1	(37.5)	(0.6)	180.4	34.3	76.0
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
Net income attributable to Rexnord	28.5	48.5	56.6	46.5	47.2	25.4	(37.6)	(0.7)	180.1	34.3	75.9
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 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
Basic net income (loss) per share attributable to Rexnord common stockholders
Continuing operations (in dollars per share)	$ 0.23	$ 0.40	$ 0.48	$ 0.40	$ 0.40	$ 0.45	$ 0.39	$ 0.35	$ 1.50	$ 1.58	$ 1.76
Discontinued operations (in dollars per share)	0	0	0	(0.02)	0	(0.27)	(0.80)	(0.41)	(0.02)	(1.48)	(1.26)
Net income (in dollars per share)	0.23	0.40	0.48	0.39	0.39	0.19	(0.42)	(0.06)	1.48	0.11	0.51
Diluted net income (loss) per share attributable to Rexnord common stockholders
Continuing operations (in dollars per share)	0.23	0.39	0.46	0.39	0.39	0.43	0.37	0.34	1.46	1.53	1.69
Discontinued operations (in dollars per share)	0	0	0	(0.01)	0	(0.23)	(0.68)	(0.40)	(0.01)	(1.25)	(1.07)
Net income (in dollars per share)	$ 0.23	$ 0.39	$ 0.46	$ 0.38	$ 0.38	$ 0.21	$ (0.30)	$ (0.06)	$ 1.45	$ 0.28	$ 0.62
Actuarial (loss) gain on pension and postretirement benefit obligations	$ (35.8)								$ (36.6)	$ 0.4	$ 3.3
Non-cash asset impairment									0.0	0.3	0.8
Discontinued Operations, Held-for-sale
Effect of Fourth Quarter Events [Line Items]
Loss from discontinued operations, net of tax									(1.8)	(154.7)	(130.6)
Diluted net income (loss) per share attributable to Rexnord common stockholders
Non-cash asset impairment							$ 82.0	$ 44.0	0.0	126.0	111.2
Loss on sale of discontinued operations						$ 19.7			$ 1.8	$ 22.5	$ 0.0