Debt - Debt Obligations (Details) - USD ($) $ in Millions	Sep. 30, 2022	Mar. 31, 2022
Debt Instrument [Line Items]
Long-term debt	$ 7,338.7	$ 7,837.2
Less: Debt discount	(14.1)	(124.6)
Less: Debt issuance costs	(21.1)	(25.2)
Net long-term debt including current maturities	7,303.5	7,687.4
Less: Current maturities	(998.6)	0.0
Net long-term debt	6,304.9	7,687.4
Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt	972.1	1,399.1
Less: Debt issuance costs	(9.4)	(10.6)
Senior Indebtedness
Debt Instrument [Line Items]
Long-term debt	$ 6,572.1	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	(0.8)	(1.3)
Less: Debt issuance costs	$ (1.6)	(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	(0.9)	(1.3)
Less: Debt issuance costs	$ (0.5)	(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	(1.8)	(2.5)
Less: Debt issuance costs	$ (0.9)	(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	(1.8)	(2.2)
Less: Debt issuance costs	$ (1.1)	(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	(8.8)	(10.2)
Less: Debt issuance costs	(1.1)	(1.3)
Convertible Debt
Debt Instrument [Line Items]
Long-term debt	$ 766.6	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	$ 12.4	34.4
Less: Debt discount	0.0	(3.7)
Less: Debt issuance costs	$ (0.1)	(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	$ 82.2	128.1
Less: Debt discount	0.0	(23.4)
Less: Debt issuance costs	$ (0.5)	(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	$ (5.8)	(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, excluding unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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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, excluding unamortized premium (discount) and debt issuance cost, of long-term debt classified as noncurrent. Excludes lease obligation.

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