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, 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
Effect of Fourth Quarter Events [Line Items]
Total	$ 537.5	$ 485.0	$ 524.8	$ 503.6	$ 517.9	$ 436.7	$ 453.8	$ 443.2	$ 2,050.9	$ 1,851.6	$ 1,712.5
Gross profit	201.8	184.3	203.2	195.5	198.7	170.1	173.6	164.1	784.8	706.5	626.4
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
Loss from discontinued operations, net of tax	(0.4)	(27.8)	(83.7)	(42.8)	(119.9)	(4.3)	(3.5)	(2.9)	(154.7)	(130.6)	(17.6)
Net (loss) income	47.3	25.1	(37.5)	(0.6)	(61.9)	81.6	29.8	26.5	34.3	76.0	74.1
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
Net income (loss) attributable to Rexnord	47.2	25.4	(37.6)	(0.7)	(62.0)	81.6	29.8	26.5	34.3	75.9	74.1
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 (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
Basic net income (loss) per share attributable to Rexnord common stockholders
Continuing operations (in dollars per share)	$ 0.40	$ 0.45	$ 0.39	$ 0.35	$ 0.50	$ 0.77	$ 0.26	$ 0.23	$ 1.58	$ 1.76	$ 0.82
Discontinued operations (in dollars per share)	0.00	(0.27)	(0.80)	(0.41)	(1.15)	(0.04)	(0.03)	(0.03)	(1.48)	(1.26)	(0.17)
Net income (in dollars per share)	0.39	0.19	(0.42)	(0.06)	(0.65)	0.73	0.23	0.20	0.11	0.51	0.65
Diluted net income (loss) per share attributable to Rexnord common stockholders
Continuing operations (in dollars per share)	0.39	0.43	0.37	0.34	0.47	0.70	0.26	0.23	1.53	1.69	0.81
Discontinued operations (in dollars per share)	0.00	(0.23)	(0.68)	(0.40)	(0.98)	(0.04)	(0.03)	(0.03)	(1.25)	(1.07)	(0.17)
Net income (in dollars per share)	$ 0.38	$ 0.21	$ (0.30)	$ (0.06)	$ (0.51)	$ 0.67	$ 0.23	$ 0.20	$ 0.28	$ 0.62	$ 0.64
Non-cash asset impairment									$ 0.3	$ 0.8	$ 1.5
Net effect to deferred taxes for U.S. Tax Reform						$ (65.9)			0.8	(67.1)	0.0
Discontinued Operations, Held-for-sale
Effect of Fourth Quarter Events [Line Items]
Loss from discontinued operations, net of tax									(154.7)	(130.6)	(17.6)
Diluted net income (loss) per share attributable to Rexnord common stockholders
Non-cash asset impairment			$ 82.0	$ 44.0					126.0	111.2	0.0
Loss on sale of discontinued operations		$ 19.7							$ 22.5	$ 0.0	$ 0.0
Non-cash Impairment					$ 111.2