Guarantor Subsidiaries - Condensed Consolidating Statement of Operations (Details) - USD ($) $ 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
Condensed Income Statements, Captions [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
Cost of sales									1,250.3	1,266.1	1,145.1
Gross profit	216.5	191.7	208.2	201.6	201.8	184.3	203.2	195.5	818.0	784.8	706.5
Selling, general and administrative expenses									432.8	433.1	393.8
Restructuring and other similar charges									15.5	12.1	14.1
Amortization of intangible assets									35.4	34.0	32.2
Income from operations									334.3	305.6	266.4
Interest income (expense), net:
To third parties									(58.6)	(69.9)	(75.1)
To affiliates									0.0	0.0	0.0
Gain (loss) on the extinguishment of debt									1.0	4.3	(11.9)
Actuarial loss on pension and postretirement benefit obligations	(35.8)								(36.6)	0.4	3.3
Other income (expense), net									(3.8)	(1.6)	4.4
Income from continuing operations before income taxes									236.3	238.8	187.1
Provision for income taxes									(54.1)	(53.4)	19.5
Equity method investment income									0.0	3.6	0.0
Income (loss) before equity in income of subsidiaries									182.2	189.0	206.6
Equity in earnings (loss) of subsidiaries									0.0	0.0	0.0
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
Comprehensive income (loss)									152.6	11.8	138.9
Eliminations
Condensed Income Statements, Captions [Line Items]
Net sales									(161.1)	(186.7)	(172.6)
Cost of sales									(161.1)	(186.7)	(172.6)
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
Actuarial loss on pension and postretirement benefit obligations									0.0	0.0	0.0
Other income (expense), 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									(381.5)	(19.6)	(236.5)
Net income from continuing operations									(381.5)	(19.6)	(236.5)
Loss from discontinued operations, net of tax									0.0	0.0	0.0
Net income									(381.5)	(19.6)	(236.5)
Non-controlling interest income									0.0	0.0	0.0
Net income attributable to Rexnord									(381.5)	(19.6)	(236.5)
Dividends on preferred stock									0.0	0.0	0.0
Net income attributable to Rexnord common stockholders									(381.5)	(19.6)	(236.5)
Comprehensive income (loss)									(381.5)	(19.6)	(236.5)
Parent
Condensed Income Statements, Captions [Line Items]
Net sales									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
Gain (loss) on the extinguishment of debt									0.0	0.0	0.0
Actuarial loss on pension and postretirement benefit obligations									0.0	0.0	0.0
Other income (expense), net									0.0	0.0	0.0
Income from continuing operations before income taxes									10.3	2.0	3.0
Provision for income taxes									0.0	0.0	0.0
Equity method investment income										0.0
Income (loss) before equity in income of subsidiaries									10.3	2.0	3.0
Equity in earnings (loss) of subsidiaries									170.1	32.3	73.0
Net income from continuing operations									180.4	34.3	76.0
Loss from discontinued operations, net of tax									0.0	0.0	0.0
Net income									180.4	34.3	76.0
Non-controlling interest income									0.0	0.0	0.0
Net income attributable to Rexnord									180.4	34.3	76.0
Dividends on preferred stock									(14.4)	(23.2)	(23.2)
Net income attributable to Rexnord common stockholders									166.0	11.1	52.8
Comprehensive income (loss)									180.4	34.3	76.0
Parent | Reportable Legal Entities
Interest income (expense), net:
To affiliates									10.3	2.0	3.0
Issuers
Condensed Income Statements, Captions [Line Items]
Net sales									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									(56.7)	(68.2)	(75.3)
Gain (loss) on the extinguishment of debt									(2.1)	(0.7)	(11.9)
Actuarial loss on pension and postretirement benefit obligations									0.0	0.0	0.0
Other income (expense), net									0.1	0.3	0.0
Income from continuing operations before income taxes									(17.4)	(6.9)	(59.8)
Provision for income taxes									(0.5)	0.0	0.0
Equity method investment income										0.0
Income (loss) before equity in income of subsidiaries									(17.9)	(6.9)	(59.8)
Equity in earnings (loss) of subsidiaries									188.0	39.2	132.8
Net income from continuing operations									170.1	32.3	73.0
Loss from discontinued operations, net of tax									0.0	0.0	0.0
Net income									170.1	32.3	73.0
Non-controlling interest income									0.0	0.0	0.0
Net income attributable to Rexnord									170.1	32.3	73.0
Dividends on preferred stock									0.0	0.0	0.0
Net income attributable to Rexnord common stockholders									170.1	32.3	73.0
Comprehensive income (loss)									167.9	22.5	89.2
Issuers | Reportable Legal Entities
Interest income (expense), net:
To affiliates									41.3	61.7	27.4
Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Net sales									1,568.4	1,565.0	1,457.3
Cost of sales									944.7	977.1	910.3
Gross profit									623.7	587.9	547.0
Selling, general and administrative expenses									331.3	328.8	310.5
Restructuring and other similar charges									8.8	7.6	12.8
Amortization of intangible assets									28.1	27.5	26.6
Income from operations									255.5	224.0	197.1
Interest income (expense), net:
To third parties									(2.7)	(2.0)	(0.4)
Gain (loss) on the extinguishment of debt									3.3	5.0	0.0
Actuarial loss on pension and postretirement benefit obligations									(35.7)	1.0	1.8
Other income (expense), net									(1.1)	3.1	(3.1)
Income from continuing operations before income taxes									202.9	177.9	182.3
Provision for income taxes									(38.3)	(44.5)	39.7
Equity method investment income										0.0
Income (loss) before equity in income of subsidiaries									164.6	133.4	222.0
Equity in earnings (loss) of subsidiaries									23.4	(51.9)	30.7
Net income from continuing operations									188.0	81.5	252.7
Loss from discontinued operations, net of tax									0.0	(42.3)	(119.9)
Net income									188.0	39.2	132.8
Non-controlling interest income									0.0	0.0	0.0
Net income attributable to Rexnord									188.0	39.2	132.8
Dividends on preferred stock									0.0	0.0	0.0
Net income attributable to Rexnord common stockholders									188.0	39.2	132.8
Comprehensive income (loss)									186.3	34.1	135.6
Guarantor Subsidiaries | Reportable Legal Entities
Interest income (expense), net:
To affiliates									(16.4)	(53.2)	(13.1)
Non-Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Net sales									661.0	672.6	566.9
Cost of sales									466.7	475.7	407.4
Gross profit									194.3	196.9	159.5
Selling, general and administrative expenses									101.5	104.3	83.3
Restructuring and other similar charges									6.7	4.5	1.3
Amortization of intangible assets									7.3	6.5	5.6
Income from operations									78.8	81.6	69.3
Interest income (expense), net:
To third parties									0.8	0.3	0.6
Gain (loss) on the extinguishment of debt									(0.2)	0.0	0.0
Actuarial loss on pension and postretirement benefit obligations									(0.9)	(0.6)	1.5
Other income (expense), net									(2.8)	(5.0)	7.5
Income from continuing operations before income taxes									40.5	65.8	61.6
Provision for income taxes									(15.3)	(8.9)	(20.2)
Equity method investment income										3.6
Income (loss) before equity in income of subsidiaries									25.2	60.5	41.4
Equity in earnings (loss) of subsidiaries									0.0	0.0	0.0
Net income from continuing operations									25.2	60.5	41.4
Loss from discontinued operations, net of tax									(1.8)	(112.4)	(10.7)
Net income									23.4	(51.9)	30.7
Non-controlling interest income									0.3	0.0	0.1
Net income attributable to Rexnord									23.1	(51.9)	30.6
Dividends on preferred stock									0.0	0.0	0.0
Net income attributable to Rexnord common stockholders									23.1	(51.9)	30.6
Comprehensive income (loss)									(0.5)	(59.5)	74.6
Non-Guarantor Subsidiaries | Reportable Legal Entities
Interest income (expense), net:
To affiliates									$ (35.2)	$ (10.5)	$ (17.3)