Guarantor Subsidiaries - Condensed Consolidating Statement of Operations (Details) - USD ($) $ 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
Condensed Income Statements, Captions [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
Cost of sales									1,266.1	1,145.1	1,086.1
Gross profit	201.8	184.3	203.2	195.5	198.7	170.1	173.6	164.1	784.8	706.5	626.4
Selling, general and administrative expenses									433.1	393.8	356.1
Restructuring and other similar charges									12.1	14.1	26.1
Amortization of intangible assets									34.0	32.2	41.0
Income from operations									305.6	266.4	203.2
Interest income (expense), net:
To third parties									(69.9)	(75.1)	(88.3)
To affiliates									0.0	0.0	0.0
Gain (loss) on the extinguishment of debt									4.3	(11.9)	(7.8)
Other (expense) income, net									(1.2)	7.7	0.2
Income from continuing operations before income taxes									238.8	187.1	107.3
Provision for income taxes									(53.4)	19.5	(15.6)
Equity method investment income									3.6	0.0	0.0
Income (loss) before equity in income of subsidiaries									189.0	206.6	91.7
Equity in earnings (loss) of subsidiaries									0.0	0.0	0.0
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	(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)	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
Comprehensive income (loss)									11.8	138.9	76.1
Eliminations
Condensed Income Statements, Captions [Line Items]
Total									(186.7)	(172.6)	(115.0)
Cost of sales									(186.7)	(172.6)	(115.0)
Gross profit									0.0	0.0	0.0
Selling, general and administrative expenses									0.0	0.0	0.0
Restructuring and other similar charges									0.0	0.0	0.0
Amortization of intangible assets									0.0	0.0	0.0
Income from operations									0.0	0.0	0.0
Interest income (expense), net:
To third parties									0.0	0.0	0.0
To affiliates									0.0	0.0	0.0
Gain (loss) on the extinguishment of debt									0.0	0.0	0.0
Other (expense) income, net									0.0	0.0	0.0
Income from continuing operations before income taxes									0.0	0.0	0.0
Provision for income taxes									0.0	0.0	0.0
Equity method investment income									0.0
Income (loss) before equity in income of subsidiaries									0.0	0.0	0.0
Equity in earnings (loss) of subsidiaries									(19.6)	(236.5)	(181.0)
Net income from continuing operations									(19.6)	(236.5)	(181.0)
Loss from discontinued operations									0.0	0.0	0.0
Net income (loss)									(19.6)	(236.5)	(181.0)
Non-controlling interest income									0.0	0.0	0.0
Net income (loss) attributable to Rexnord									(19.6)	(236.5)	(181.0)
Dividends on preferred stock									0.0	0.0	0.0
Net income (loss) attributable to Rexnord common stockholders									(19.6)	(236.5)	(181.0)
Comprehensive income (loss)									(19.6)	(236.5)	(181.0)
Parent
Condensed Income Statements, Captions [Line Items]
Total									0.0	0.0	0.0
Cost of sales									0.0	0.0	0.0
Gross profit									0.0	0.0	0.0
Selling, general and administrative expenses									0.0	0.0	0.0
Restructuring and other similar charges									0.0		0.0
Amortization of intangible assets									0.0	0.0	0.0
Income from operations									0.0	0.0	0.0
Interest income (expense), net:
To third parties									0.0	0.0	0.0
To affiliates									2.0	3.0	1.1
Gain (loss) on the extinguishment of debt									0.0	0.0	0.0
Other (expense) income, net									0.0	0.0	0.0
Income from continuing operations before income taxes									2.0	3.0	1.1
Provision for income taxes									0.0	0.0	0.0
Equity method investment income									0.0
Income (loss) before equity in income of subsidiaries									2.0	3.0	1.1
Equity in earnings (loss) of subsidiaries									32.3	73.0	73.0
Net income from continuing operations									34.3	76.0	74.1
Loss from discontinued operations									0.0	0.0	0.0
Net income (loss)									34.3	76.0	74.1
Non-controlling interest income									0.0	0.0	0.0
Net income (loss) attributable to Rexnord									34.3	76.0	74.1
Dividends on preferred stock									(23.2)	(23.2)	(7.3)
Net income (loss) attributable to Rexnord common stockholders									11.1	52.8	66.8
Comprehensive income (loss)									34.3	76.0	74.1
Issuers
Condensed Income Statements, Captions [Line Items]
Total									0.0	0.0	0.0
Cost of sales									0.0	0.0	0.0
Gross profit									0.0	0.0	0.0
Selling, general and administrative expenses									0.0	0.0	0.0
Restructuring and other similar charges									0.0	0.0	0.0
Amortization of intangible assets									0.0	0.0	0.0
Income from operations									0.0	0.0	0.0
Interest income (expense), net:
To third parties									(68.2)	(75.3)	(88.1)
To affiliates									61.7	27.4	74.3
Gain (loss) on the extinguishment of debt									(0.7)	(11.9)	(7.8)
Other (expense) income, net									0.3	0.0	(0.3)
Income from continuing operations before income taxes									(6.9)	(59.8)	(21.9)
Provision for income taxes									0.0	0.0	(0.1)
Equity method investment income									0.0
Income (loss) before equity in income of subsidiaries									(6.9)	(59.8)	(22.0)
Equity in earnings (loss) of subsidiaries									39.2	132.8	95.0
Net income from continuing operations									32.3	73.0	73.0
Loss from discontinued operations									0.0	0.0	0.0
Net income (loss)									32.3	73.0	73.0
Non-controlling interest income									0.0	0.0	0.0
Net income (loss) attributable to Rexnord									32.3	73.0	73.0
Dividends on preferred stock									0.0	0.0	0.0
Net income (loss) attributable to Rexnord common stockholders									32.3	73.0	73.0
Comprehensive income (loss)									22.5	89.2	77.5
Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Total									1,565.0	1,457.3	1,372.3
Cost of sales									977.1	910.3	878.0
Gross profit									587.9	547.0	494.3
Selling, general and administrative expenses									328.8	310.5	286.1
Restructuring and other similar charges									7.6	12.8	24.9
Amortization of intangible assets									27.5	26.6	35.1
Income from operations									224.0	197.1	148.2
Interest income (expense), net:
To third parties									(2.0)	(0.4)	(0.4)
To affiliates									(53.2)	(13.1)	(53.4)
Gain (loss) on the extinguishment of debt									5.0	0.0	0.0
Other (expense) income, net									4.1	(1.3)	(0.4)
Income from continuing operations before income taxes									177.9	182.3	94.0
Provision for income taxes									(44.5)	39.7	(0.4)
Equity method investment income									0.0
Income (loss) before equity in income of subsidiaries									133.4	222.0	93.6
Equity in earnings (loss) of subsidiaries									(51.9)	30.7	13.0
Net income from continuing operations									81.5	252.7	106.6
Loss from discontinued operations									(42.3)	(119.9)	(11.6)
Net income (loss)									39.2	132.8	95.0
Non-controlling interest income									0.0	0.0	0.0
Net income (loss) attributable to Rexnord									39.2	132.8	95.0
Dividends on preferred stock									0.0	0.0	0.0
Net income (loss) attributable to Rexnord common stockholders									39.2	132.8	95.0
Comprehensive income (loss)									34.1	135.6	86.0
Non-Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Total									672.6	566.9	455.2
Cost of sales									475.7	407.4	323.1
Gross profit									196.9	159.5	132.1
Selling, general and administrative expenses									104.3	83.3	70.0
Restructuring and other similar charges									4.5	1.3	1.2
Amortization of intangible assets									6.5	5.6	5.9
Income from operations									81.6	69.3	55.0
Interest income (expense), net:
To third parties									0.3	0.6	0.2
To affiliates									(10.5)	(17.3)	(22.0)
Gain (loss) on the extinguishment of debt									0.0	0.0	0.0
Other (expense) income, net									(5.6)	9.0	0.9
Income from continuing operations before income taxes									65.8	61.6	34.1
Provision for income taxes									(8.9)	(20.2)	(15.1)
Equity method investment income									3.6
Income (loss) before equity in income of subsidiaries									60.5	41.4	19.0
Equity in earnings (loss) of subsidiaries									0.0	0.0	0.0
Net income from continuing operations									60.5	41.4	19.0
Loss from discontinued operations									(112.4)	(10.7)	(6.0)
Net income (loss)									(51.9)	30.7	13.0
Non-controlling interest income									0.0	0.1	0.0
Net income (loss) attributable to Rexnord									(51.9)	30.6	13.0
Dividends on preferred stock									0.0	0.0	0.0
Net income (loss) attributable to Rexnord common stockholders									(51.9)	30.6	13.0
Comprehensive income (loss)									$ (59.5)	$ 74.6	$ 19.5