Debt and Credit Facility - Credit Facility (Details) - USD ($)		1 Months Ended	12 Months Ended
		May 31, 2018	Mar. 31, 2019		Mar. 31, 2018		Mar. 31, 2017		Feb. 28, 2017
Line of Credit Facility [Line Items]
Debt issuance amortization		$ 24,400,000	$ 83,600,000		$ 40,100,000				$ 33,700,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity		3,840,000,000	3,600,000,000		3,120,000,000
Debt issuance amortization		13,600,000
Extinguishment of debt, amount			244,300,000
Proceeds from long-term lines of credit	[1]		4,416,500,000		187,000,000.0		$ 1,537,000,000.0
Total consolidated debt, maximum			$ 700,000,000
Interest coverage ratio, less than			3.25
Interest rate spread on overdue principal in event of default			2.00%
Interest rate spread on overdue amounts in event of default			2.00%
Term Loan Facility
Line of Credit Facility [Line Items]
Debt issuance amortization		34,700,000
Proceeds from long-term lines of credit		$ 3,000,000,000.0	$ 3,000,000,000.0	[1]	$ 0	[1]	$ 0	[1]
Quarterly amortization payments, percent			0.25%
Repayments of long-term debt			$ 1,090,000,000.00
Proceeds from lines of credit			500,000,000.0
Loss on settlement of debt			(11,500,000)
Foreign Line of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity			250,000,000.0
Standby Letters of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity			50,000,000.0
Line of Credit Facility Swingline Loan Sublimit
Line of Credit Facility [Line Items]
Maximum borrowing capacity			25,000,000.0
2023 Tranche | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity			$ 3,600,000,000
Leverage Ratio Percent One | Revolving Credit Facility
Line of Credit Facility [Line Items]
Total leverage ratio, maximum			6.75
Total leverage ratio, temporary maximum allowed, next three quarters			4.75
Leverage Ratio Percent One | Term Loan Facility
Line of Credit Facility [Line Items]
Mandatory prepayment of excess cash flow, percentage			50.00%
Leverage Ratio Percent Two | Revolving Credit Facility
Line of Credit Facility [Line Items]
Total leverage ratio, maximum			6.25
Total leverage ratio, temporary maximum allowed, next three quarters			4.25
Leverage Ratio Percent Two | Term Loan Facility
Line of Credit Facility [Line Items]
Mandatory prepayment of excess cash flow, percentage			25.00%
Leverage Ratio Percent Three | Revolving Credit Facility
Line of Credit Facility [Line Items]
Total leverage ratio, maximum			5.75
Total leverage ratio, temporary maximum allowed, next three quarters			3.75
Leverage Ratio Percent Three | Term Loan Facility
Line of Credit Facility [Line Items]
Mandatory prepayment of excess cash flow, percentage			0.00%
Minimum | Base Rate | 2023 Tranche | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.00%
Minimum | London Interbank Offered Rate (LIBOR) | 2023 Tranche | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.00%
Maximum | Base Rate | 2023 Tranche | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.00%
Maximum | London Interbank Offered Rate (LIBOR) | 2023 Tranche | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate			2.00%

[1] During the fiscal year ended March 31, 2018, the Company issued $111.3 million principal amount of 2017 Junior Convertible Notes and 3.2 million shares of common stock in exchange for $111.3 million principal amount of 2007 Junior Convertible Notes. Refer to Note 12 Debt and Credit Facility for further discussion.