Debt - Debt Obligations (Details) - USD ($) $ in Millions	Jun. 30, 2022	Mar. 31, 2022
Debt Instrument [Line Items]
Long-term debt	$ 7,603.6	$ 7,837.2
Less: Debt discount	(15.9)	(124.6)
Less: Debt issuance costs	(23.8)	(25.2)
Net long-term debt including current maturities	7,563.9	7,687.4
Less: Current maturities	0.0	0.0
Net long-term debt	7,563.9	7,687.4
Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt	1,200.1	1,399.1
Less: Debt issuance costs	(10.1)	(10.6)
Senior Indebtedness
Debt Instrument [Line Items]
Long-term debt	$ 6,800.1	6,999.1
Senior Indebtedness \| 4.333% 2023 Notes
Debt Instrument [Line Items]
Coupon Interest Rate	4.333%
Effective Interest Rate	4.70%
Long-term debt	$ 1,000.0	1,000.0
Less: Debt discount	(1.1)	(1.3)
Less: Debt issuance costs	$ (2.2)	(2.9)
Senior Indebtedness \| 2.670% 2023 Notes
Debt Instrument [Line Items]
Coupon Interest Rate	2.67%
Effective Interest Rate	2.80%
Long-term debt	$ 1,000.0	1,000.0
Less: Debt discount	(1.1)	(1.3)
Less: Debt issuance costs	$ (0.6)	(0.8)
Senior Indebtedness \| 0.972% 2024 Notes
Debt Instrument [Line Items]
Coupon Interest Rate	0.972%
Effective Interest Rate	1.10%
Long-term debt	$ 1,400.0	1,400.0
Less: Debt discount	(2.2)	(2.5)
Less: Debt issuance costs	$ (1.1)	(1.3)
Senior Indebtedness \| 0.983% 2024 Notes
Debt Instrument [Line Items]
Coupon Interest Rate	0.983%
Effective Interest Rate	1.10%
Long-term debt	$ 1,000.0	1,000.0
Less: Debt discount	(2.0)	(2.2)
Less: Debt issuance costs	$ (1.2)	(1.4)
Senior Indebtedness \| 4.250% 2025 Notes
Debt Instrument [Line Items]
Coupon Interest Rate	4.25%
Effective Interest Rate	4.60%
Long-term debt	$ 1,200.0	1,200.0
Less: Debt discount	(9.5)	(10.2)
Less: Debt issuance costs	(1.2)	(1.3)
Convertible Debt
Debt Instrument [Line Items]
Long-term debt	$ 803.5	838.1
Senior Subordinated Convertible Debt \| 2015 Senior Convertible Debt
Debt Instrument [Line Items]
Coupon Interest Rate	1.625%
Effective Interest Rate	1.80%
Long-term debt	$ 34.4	34.4
Less: Debt discount	0.0	(3.7)
Less: Debt issuance costs	$ (0.2)	(0.1)
Senior Subordinated Convertible Debt \| 2017 Senior Convertible Debt
Debt Instrument [Line Items]
Coupon Interest Rate	1.625%
Effective Interest Rate	1.80%
Long-term debt	$ 97.1	128.1
Less: Debt discount	0.0	(23.4)
Less: Debt issuance costs	$ (0.6)	(0.6)
Senior Subordinated Convertible Debt \| 2020 Senior Convertible Debt
Debt Instrument [Line Items]
Coupon Interest Rate	0.125%
Effective Interest Rate	0.50%
Long-term debt	$ 665.5	665.5
Less: Debt discount	0.0	(75.3)
Less: Debt issuance costs	$ (6.5)	(6.2)
Junior Subordinated Convertible Debt \| 2017 Junior Convertible Debt
Debt Instrument [Line Items]
Coupon Interest Rate	2.25%
Effective Interest Rate	2.30%
Long-term debt	$ 6.5	10.1
Less: Debt discount	0.0	(4.7)
Less: Debt issuance costs	$ (0.1)	$ 0.0

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after accumulated amortization, of debt discount.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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