Guarantor Subsidiaries - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Current assets:
Cash and cash equivalents	$ 573.4	$ 292.5
Receivables, net	334.7	334.3
Inventories	317.5	316.5
Other current assets	38.7	39.6
Total current assets	1,264.3	982.9
Property, plant and equipment, net	378.8	383.0
Intangible assets, net	514.2	511.5
Goodwill	1,321.9	1,299.7	$ 1,276.1
Investment in:
Other assets	147.9	82.6
Total assets	3,627.1	3,259.7	3,423.7
Current liabilities:
Current maturities of debt	76.4	1.2
Trade payables	185.6	191.7
Compensation and benefits	61.8	63.7
Current portion of pension and postretirement benefit obligations	3.2	3.3
Other current liabilities	128.5	137.1
Total current liabilities	455.5	397.0
Long-term debt	1,397.0	1,236.8
Note payable to affiliates, net	0.0	0.0
Pension and postretirement benefit obligations	189.6	158.0
Deferred income taxes	121.0	125.9
Other liabilities	150.3	111.0
Total liabilities	2,313.4	2,028.7
Total stockholders' equity	1,313.7	1,231.0	$ 1,212.8	$ 1,070.6
Total liabilities and stockholders' equity	3,627.1	3,259.7
Eliminations
Current assets:
Cash and cash equivalents	0.0	0.0
Receivables, net	0.0	0.0
Inventories	0.0	0.0
Other current assets	0.0	0.0
Total current assets	0.0	0.0
Property, plant and equipment, net	0.0	0.0
Intangible assets, net	0.0	0.0
Goodwill	0.0	0.0
Investment in:
Total assets	(5,327.1)	(4,905.5)
Current liabilities:
Current maturities of debt	0.0	0.0
Trade payables	0.0	0.0
Compensation and benefits	0.0	0.0
Current portion of pension and postretirement benefit obligations	0.0	0.0
Other current liabilities	0.0	0.0
Total current liabilities	0.0	0.0
Long-term debt	0.0	0.0
Note payable to affiliates, net	0.0	0.0
Pension and postretirement benefit obligations	0.0	0.0
Deferred income taxes	0.0	0.0
Other liabilities	0.0	0.0
Total liabilities	0.0	0.0
Total stockholders' equity	(5,327.1)	(4,905.5)
Total liabilities and stockholders' equity	(5,327.1)	(4,905.5)
Issuer subsidiaries
Investment in:
Subsidiaries	(1,381.1)	(1,212.1)
Guarantor subsidiaries
Investment in:
Subsidiaries	(3,324.9)	(3,146.0)
Non-guarantor subsidiaries
Investment in:
Subsidiaries	(621.1)	(547.4)
Parent | Reportable Legal Entities
Current assets:
Cash and cash equivalents	11.0	1.4
Receivables, net	0.0	0.0
Inventories	0.0	0.0
Other current assets	0.0	0.0
Total current assets	11.0	1.4
Property, plant and equipment, net	0.0	0.0
Intangible assets, net	0.0	0.0
Goodwill	0.0	0.0
Investment in:
Subsidiaries	1,381.1	1,212.1
Other assets	0.0	0.0
Total assets	1,392.1	1,213.5
Current liabilities:
Current maturities of debt	0.0	0.0
Trade payables	0.0	0.0
Compensation and benefits	0.0	0.0
Current portion of pension and postretirement benefit obligations	0.0	0.0
Other current liabilities	0.0	3.0
Total current liabilities	0.0	3.0
Long-term debt	0.0	0.0
Note payable to affiliates, net	77.9
Note receivable from affiliates, net		(20.7)
Pension and postretirement benefit obligations	0.0	0.0
Deferred income taxes	0.0	0.0
Other liabilities	0.5	0.2
Total liabilities	78.4	(17.5)
Total stockholders' equity	1,313.7	1,231.0
Total liabilities and stockholders' equity	1,392.1	1,213.5
Issuers | Reportable Legal Entities
Current assets:
Cash and cash equivalents	0.4	0.2
Receivables, net	0.0	0.0
Inventories	0.0	0.0
Other current assets	0.0	0.0
Total current assets	0.4	0.2
Property, plant and equipment, net	0.0	0.0
Intangible assets, net	0.0	0.0
Goodwill	0.0	0.0
Investment in:
Subsidiaries	3,324.9	3,146.0
Other assets	0.0	1.1
Total assets	3,325.3	3,147.3
Current liabilities:
Current maturities of debt	0.0	0.0
Trade payables	0.0	0.0
Compensation and benefits	0.0	0.0
Current portion of pension and postretirement benefit obligations	0.0	0.0
Other current liabilities	7.9	7.5
Total current liabilities	7.9	7.5
Long-term debt	1,290.9	1,213.4
Note payable to affiliates, net	645.4	714.3
Pension and postretirement benefit obligations	0.0	0.0
Deferred income taxes	0.0	0.0
Other liabilities	0.0	0.0
Total liabilities	1,944.2	1,935.2
Total stockholders' equity	1,381.1	1,212.1
Total liabilities and stockholders' equity	3,325.3	3,147.3
Guarantor Subsidiaries | Reportable Legal Entities
Current assets:
Cash and cash equivalents	383.9	107.7
Receivables, net	223.5	219.6
Inventories	224.8	214.3
Other current assets	20.5	13.0
Total current assets	852.7	554.6
Property, plant and equipment, net	256.1	251.2
Intangible assets, net	424.8	411.6
Goodwill	1,043.6	1,017.1
Investment in:
Subsidiaries	621.1	547.4
Other assets	88.7	63.1
Total assets	3,287.0	2,845.0
Current liabilities:
Current maturities of debt	75.4	0.1
Trade payables	123.9	129.7
Compensation and benefits	42.4	42.4
Current portion of pension and postretirement benefit obligations	1.8	1.9
Other current liabilities	79.9	90.3
Total current liabilities	323.4	264.4
Long-term debt	101.8	14.4
Note receivable from affiliates, net	(795.9)	(879.0)
Pension and postretirement benefit obligations	142.8	112.9
Deferred income taxes	98.6	98.8
Other liabilities	91.4	87.4
Total liabilities	(37.9)	(301.1)
Total stockholders' equity	3,324.9	3,146.1
Total liabilities and stockholders' equity	3,287.0	2,845.0
Non-Guarantor Subsidiaries | Reportable Legal Entities
Current assets:
Cash and cash equivalents	178.1	183.2
Receivables, net	111.2	114.7
Inventories	92.7	102.2
Other current assets	18.2	26.6
Total current assets	400.2	426.7
Property, plant and equipment, net	122.7	131.8
Intangible assets, net	89.4	99.9
Goodwill	278.3	282.6
Investment in:
Other assets	59.2	18.4
Total assets	949.8	959.4
Current liabilities:
Current maturities of debt	1.0	1.1
Trade payables	61.7	62.0
Compensation and benefits	19.4	21.3
Current portion of pension and postretirement benefit obligations	1.4	1.4
Other current liabilities	40.7	36.3
Total current liabilities	124.2	122.1
Long-term debt	4.3	9.0
Note payable to affiliates, net	72.6	185.4
Pension and postretirement benefit obligations	46.8	45.1
Deferred income taxes	22.4	27.1
Other liabilities	58.4	23.4
Total liabilities	328.7	412.1
Total stockholders' equity	621.1	547.3
Total liabilities and stockholders' equity	$ 949.8	$ 959.4