Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Amortizing Intangibles:
Amortization charges	$ 4.3	$ 2.1	$ 2.2
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	4.6
Amortization expense, year four	4.6
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	21.3
Patents [Member]
Amortizing Intangibles:
Amortization charges	1.4	1.5	1.6
Amortization expense, year four	1.4
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	8.9
Customer Relationships
Amortizing Intangibles:
Amortization charges	$ 2.9	$ 0.6	$ 0.6
Useful life	12 years 3 months 12 days	15 years 8 months 6 days
Amortization expense, year four	$ 3.2
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	$ 12.5
Purchased technology, customer relationships and patents | Weighted-average
Amortizing Intangibles:
Useful life	15 years 9 months 12 days
Finite-Lived Intangible Asset, Weighted Average Period before Next Renewal or Extension	3 years 6 months	6 months