Fair Value of Financial Instruments (Narrative details) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Mar. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt issuance costs	$ 7.1	$ 8.8
Senior Subordinated Convertible Debenture Due 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt issuance costs	17.1	18.4
Junior Subordinated Convertible Debentures Due 2037
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt issuance costs	$ 2.3	$ 2.4