Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2021	Mar. 31, 2021
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	$ 7,868.5	$ 8,904.1
Carrying Amount | Revolving Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	1,528.9	2,336.6
Carrying Amount | 3.922% 2021 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	0.0	999.0
Carrying Amount | 4.333% 2023 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	994.9	992.3
Carrying Amount | 2.670% 2023 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	997.5	996.4
Carrying Amount | 0.972% 2024 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	1,395.7	1,394.2
Carrying Amount | 0.983% 2024 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	996.0	0.0
Carrying Amount | 4.250% 2025 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	1,187.8	1,185.5
Carrying Amount | 2015 Senior Convertible Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	30.3	120.6
Carrying Amount | 2017 Senior Convertible Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	155.2	260.2
Carrying Amount | 2020 Senior Convertible Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	576.8	555.6
Carrying Amount | 2017 Junior Convertible Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	5.4	63.7
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	8,719.2	10,328.7
Fair Value | Revolving Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	1,540.1	2,346.6
Fair Value | 3.922% 2021 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	0.0	1,004.3
Fair Value | 4.333% 2023 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	1,041.8	1,022.4
Fair Value | 2.670% 2023 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	1,022.5	1,040.8
Fair Value | 0.972% 2024 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	1,389.5	1,394.0
Fair Value | 0.983% 2024 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	985.1	0.0
Fair Value | 4.250% 2025 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	1,245.0	1,252.6
Fair Value | 2015 Senior Convertible Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	132.7	485.4
Fair Value | 2017 Senior Convertible Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	495.7	731.4
Fair Value | 2020 Senior Convertible Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	841.9	778.3
Fair Value | 2017 Junior Convertible Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value disclosure for debt obligations	$ 24.9	$ 272.9