Significant Accounting Policies - Narrative (Details) - USD ($) shares in Millions	12 Months Ended			96 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2019	Apr. 01, 2019
Property, Plant and Equipment [Line Items]
Allowance for doubtful accounts	$ 3,100,000	$ 4,400,000		$ 3,100,000
Largest customer percentage of consolidated net sales	8.60%	9.20%	9.40%
Largest customer accounts receivable balance	$ 7,500,000	$ 8,500,000		$ 7,500,000
Percentage of inventory valued using LIFO	62.00%	59.00%		62.00%
Write-down of inventories	$ 3,100,000	$ 4,300,000	$ 6,500,000
Accelerated depreciation	$ 3,900,000	$ 2,300,000	9,600,000
Goodwill and intangible assets useful life	13 years	13 years
Impairment charges, long-lived assets	$ 12,100,000	$ 14,100,000	$ 26,100,000	$ 95,300,000
Antidilutive shares excluded from computation for diluted net income per share (in shares)	1.0	2.6	4.6
Currency translation gains (losses)	$ 1,900,000	$ 200,000	$ 3,600,000
Advertising costs	11,900,000	10,700,000	9,100,000
Cost of sales	1,266,100,000	1,145,100,000	1,086,100,000
Selling, general and administrative expenses	(433,100,000)	(393,800,000)	(356,100,000)
Actuarial gain on pension and post retirement benefit obligations	(400,000)	(3,300,000)	(2,600,000)
ASU 2017-07
Property, Plant and Equipment [Line Items]
Cost of sales		(2,500,000)	(2,200,000)
Selling, general and administrative expenses		700,000	0
Actuarial gain on pension and post retirement benefit obligations		3,300,000	2,600,000
Operating Segments | Water Management
Property, Plant and Equipment [Line Items]
Impairment charges, long-lived assets	1,200,000	800,000	2,700,000	12,500,000
Facility Closing
Property, Plant and Equipment [Line Items]
Impairment charges, long-lived assets	300,000	800,000	1,500,000	3,600,000
Facility Closing | Operating Segments | Water Management
Property, Plant and Equipment [Line Items]
Impairment charges, long-lived assets	$ 0	$ 0	$ 0	$ 0
Redeemable Convertible Preferred Stock
Property, Plant and Equipment [Line Items]
Antidilutive shares excluded from computation for diluted net income per share (in shares)			5.8
Customer relationships (including distribution network)
Property, Plant and Equipment [Line Items]
Goodwill and intangible assets useful life	13 years	13 years
Patents
Property, Plant and Equipment [Line Items]
Goodwill and intangible assets useful life	10 years	10 years
Tradenames
Property, Plant and Equipment [Line Items]
Goodwill and intangible assets useful life	13 years	13 years
Minimum | Scenario, Forecast | Subsequent Event | ASU 2016-02
Property, Plant and Equipment [Line Items]
Right-of-use asset					$ 65,000,000
Lease liability					65,000,000
Minimum | Customer relationships (including distribution network)
Property, Plant and Equipment [Line Items]
Goodwill and intangible assets useful life	7 years
Minimum | Patents
Property, Plant and Equipment [Line Items]
Goodwill and intangible assets useful life	3 years
Minimum | Tradenames
Property, Plant and Equipment [Line Items]
Goodwill and intangible assets useful life	3 years
Minimum | Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	10 years
Minimum | Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	5 years
Minimum | Hardware and software
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	3 years
Maximum | Scenario, Forecast | Subsequent Event | ASU 2016-02
Property, Plant and Equipment [Line Items]
Right-of-use asset					75,000,000
Lease liability					$ 75,000,000
Maximum | Customer relationships (including distribution network)
Property, Plant and Equipment [Line Items]
Goodwill and intangible assets useful life	20 years
Maximum | Patents
Property, Plant and Equipment [Line Items]
Goodwill and intangible assets useful life	15 years
Maximum | Tradenames
Property, Plant and Equipment [Line Items]
Goodwill and intangible assets useful life	15 years
Maximum | Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	30 years
Maximum | Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	10 years
Maximum | Hardware and software
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	5 years