Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Amortizing Intangibles:
Amortization charges	$ 2.1	$ 2.2	$ 2.1
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	2.1
Total amortization	$ 12.1
Purchased technology, customer relationships and patents | Weighted-average
Amortizing Intangibles:
Useful life		16 years 7 months
Finite-Lived Intangible Asset, Weighted Average Period before Next Renewal or Extension	6 months	1 year 6 months