Goodwill and Intangible Assets (Narratives) (Details)	12 Months Ended
	Mar. 31, 2017 USD ($) Reporting_Unit	Mar. 31, 2016 USD ($) Reporting_Unit	Mar. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)
Finite-Lived Intangible Assets [Line Items]
Number of reporting units | Reporting_Unit	4	4
Number of reporting units carrying goodwill | Reporting_Unit	2	2
Goodwill	$ 319,299,000	$ 170,716,000	$ 121,461,000
Duff Norton reporting unit goodwill	9,555,000	9,627,000
Rest of products reporting unit goodwill	309,744,000	161,089,000
Accumulated impairment losses for Goodwill	107,000,000	107,000,000
Impairment charges related to goodwill or intangible assets	0	0		$ 0
2016	14,000,000
2017	7,000,000
2018	7,000,000
2019	7,000,000
2020	$ 7,000,000
Weighted-average amortization periods	18 years
Indefinite-lived trademark	$ 46,018,000	29,006,000
Amortization of intangibles	$ 8,105,000	$ 5,024,000	$ 2,266,000
Trademark
Finite-Lived Intangible Assets [Line Items]
Weighted-average amortization periods	18 years
Customer relationships
Finite-Lived Intangible Assets [Line Items]
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]
Weighted-average amortization periods	6 years
STB [Member]
Finite-Lived Intangible Assets [Line Items]
Impairment charges related to goodwill or intangible assets	$ 1,125,000