Goodwill and Intangible Assets (Narratives) (Details)	3 Months Ended	12 Months Ended
	Sep. 30, 2018 USD ($)	Mar. 31, 2019 USD ($) Reporting_Unit	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2015 USD ($)
Finite-Lived Intangible Assets [Line Items]
Number of reporting units | Reporting_Unit		2
Goodwill		$ 322,816,000	$ 347,434,000	$ 319,299,000
Duff Norton reporting unit goodwill		9,611,000	9,721,000
Rest of products reporting unit goodwill		313,205,000	337,713,000
Impairment charges related to goodwill or intangible assets			0		$ 0
2016		13,500,000
2017		15,000,000
2018		15,000,000
2019		15,000,000
2020		$ 15,000,000
Weighted-average amortization periods		18 years
Indefinite-lived trademark		$ 46,981,000	48,874,000
Amortization of intangibles		$ 14,900,000	$ 15,552,000	$ 8,105,000
Trademark
Finite-Lived Intangible Assets [Line Items]
Weighted-average amortization periods		14 years
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Finite-lived		$ 2,815,000
Weighted-average amortization periods		18 years
Acquired technology
Finite-Lived Intangible Assets [Line Items]
Weighted-average amortization periods		18 years
Other
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Finite-lived		$ 226,000
Weighted-average amortization periods		6 years
Goodwill [Member]
Finite-Lived Intangible Assets [Line Items]
Gain (Loss) on Disposition of Property Plant Equipment	$ (6,174,000)	$ 6,174,000
Other | Reduced Depreciation [Member]
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Finite-lived		211,000
Customer relationships | Reduced Depreciation [Member]
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Finite-lived		$ 957,000