Goodwill and Intangible Assets Goodwill and Intangible Assets - Phantom (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Amortizing Intangibles:
Finite-Lived Intangible Assets, Amortization Expense, Year Two	$ 4.5
Finite-Lived Intangible Assets, Amortization Expense, Year Three	4.5
Amortization expense, year four	4.5
Finite-Lived Intangible Assets, Amortization Expense, Year Five	4.5
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	11.9
Patents [Member]
Amortizing Intangibles:
Finite-Lived Intangible Assets, Amortization Expense, Year Two	1.4
Finite-Lived Intangible Assets, Amortization Expense, Year Three	1.4
Amortization expense, year four	1.4
Finite-Lived Intangible Assets, Amortization Expense, Year Five	1.4
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	$ 6.1
Patents [Member] | Minimum
Amortizing Intangibles:
Useful life	10 years	10 years
Patents [Member] | Maximum [Member]
Amortizing Intangibles:
Useful life	18 years	18 years
Customer Relationships [Member]
Amortizing Intangibles:
Finite-Lived Intangible Assets, Amortization Expense, Year Two	$ 3.1
Finite-Lived Intangible Assets, Amortization Expense, Year Three	3.1
Amortization expense, year four	3.1
Finite-Lived Intangible Assets, Amortization Expense, Year Five	3.1
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	$ 5.8
Useful life	12 years 2 months 12 days	12 years 3 months 12 days
Customer Relationships [Member] | Minimum
Amortizing Intangibles:
Useful life	10 years	10 years
Customer Relationships [Member] | Maximum [Member]
Amortizing Intangibles:
Useful life	21 years	21 years