Debt - Summary of Conversion Features (Details) $ / shares in Units, shares in Millions	1 Months Ended				3 Months Ended				9 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares	Aug. 31, 2020 USD ($) shares	Jun. 30, 2020 USD ($) shares	Mar. 31, 2020 USD ($) shares	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) day	Dec. 31, 2019 USD ($)	Dec. 01, 2020 USD ($)	May 31, 2020 USD ($)	May 31, 2018 USD ($)
Debt Instrument [Line Items]
If-converted value in excess of principal									$ 1,000
Payments on settlement of convertible debt									2,252,200,000	$ 0
Shares issued to settle convertible debt					$ 1,160,100,000	$ 768,700,000	$ 651,500,000
Gain (loss) on settlement of debt	$ (129,200,000)	$ (45,100,000)	$ (21,500,000)		(142,100,000)			$ 0	(214,000,000.0)	(2,000,000.0)
Debt instrument, unamortized discount	399,600,000			$ 1,043,200,000	399,600,000				399,600,000
Gross long-term debt including current maturities	$ 9,578,600,000			10,593,300,000	9,578,600,000				9,578,600,000
Maximum
Debt Instrument [Line Items]
Option indexed to equity, strike price (in dollars per share) | $ / shares	$ 233.58
Revolving Credit Facility
Debt Instrument [Line Items]
Proceeds from borrowings on revolving loan under credit facility	$ 213,000,000.0								$ 3,073,000,000.0	$ 682,000,000.0
Term Loan Facility
Debt Instrument [Line Items]
Gain (loss) on settlement of debt	(12,900,000)
Long-term Debt
Debt Instrument [Line Items]
Extinguishment of debt, amount	1,086,500,000
Payments on settlement of convertible debt	$ 428,900,000
Shares issued to settle convertible debt (in shares) | shares	8.4
2017 Senior Convertible Debt
Debt Instrument [Line Items]
Remaining period, in years, over which unamortized debt discount will be recognized as non-cash interest expense (in years)									6 years 1 month 6 days
Payments on settlement of convertible debt	$ 155,400,000	381,800,000	643,900,000
2017 Senior Convertible Debt | Long-term Debt
Debt Instrument [Line Items]
Extinguishment of debt, amount	$ 588,800,000	$ 381,800,000	$ 643,900,000
Shares issued to settle convertible debt (in shares) | shares	3.0	2.1	2.5
Shares issued to settle convertible debt	$ 408,700,000	$ 221,100,000	$ 246,400,000
Total consideration, extinguishment of debt	1,200,000,000	602,900,000	890,300,000
Total consideration, extinguishment of debt, liability component	486,700,000	299,000,000.0	481,000,000.0
Total consideration, extinguishment of debt, equity component	655,300,000	292,200,000	390,900,000
2015 Senior Convertible Debt
Debt Instrument [Line Items]
Threshold percentage of stock price trigger									130.00%
Remaining period, in years, over which unamortized debt discount will be recognized as non-cash interest expense (in years)									4 years 1 month 6 days
Payments on settlement of convertible debt	48,500,000	414,300,000	383,300,000	615,000,000.0
2015 Senior Convertible Debt | Long-term Debt
Debt Instrument [Line Items]
Extinguishment of debt, amount	$ 90,000,000.0	$ 414,300,000	$ 383,300,000	$ 615,000,000.0
Shares issued to settle convertible debt (in shares) | shares	1.6	5.2	4.1	5.2
Shares issued to settle convertible debt	$ 221,000,000.0	$ 547,600,000	$ 405,100,000	$ 351,800,000
Total consideration, extinguishment of debt	269,600,000	961,800,000	788,400,000	966,800,000
Total consideration, extinguishment of debt, liability component	79,400,000	351,700,000	314,400,000
Total consideration, extinguishment of debt, equity component	184,500,000	$ 592,300,000	464,400,000
2017 Junior Convertible Debt
Debt Instrument [Line Items]
Remaining period, in years, over which unamortized debt discount will be recognized as non-cash interest expense (in years)									16 years 1 month 6 days
Payments on settlement of convertible debt	225,000,000.0
2017 Junior Convertible Debt | Long-term Debt
Debt Instrument [Line Items]
Extinguishment of debt, amount	$ 407,700,000
Shares issued to settle convertible debt (in shares) | shares	3.8
Shares issued to settle convertible debt	$ 530,400,000
Total consideration, extinguishment of debt	819,400,000
Total consideration, extinguishment of debt, liability component	246,300,000
Total consideration, extinguishment of debt, equity component	547,100,000
2020 Senior Convertible Debt
Debt Instrument [Line Items]
Remaining period, in years, over which unamortized debt discount will be recognized as non-cash interest expense (in years)									3 years 10 months 24 days
2020 Senior Convertible Debt | Long-term Debt
Debt Instrument [Line Items]
Debt conversion, converted instrument amount	665,500,000
2020 Senior Convertible Debt | Long-term Debt | 2017 Senior Convertible Debt
Debt Instrument [Line Items]
Debt conversion, converted instrument amount	601,500,000
2020 Senior Convertible Debt | Long-term Debt | 2017 Junior Convertible Debt
Debt Instrument [Line Items]
Debt conversion, converted instrument amount	64,000,000.0
Convertible Debt
Debt Instrument [Line Items]
Debt instrument, redemption price (percent)									100.00%
Gross long-term debt including current maturities	1,622,000,000.0			3,866,300,000	1,622,000,000.0				$ 1,622,000,000.0
Convertible Debt | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Threshold percentage of stock price trigger									130.00%
Threshold trading days | day									20
Threshold consecutive trading days | day									30
Convertible Debt | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Threshold percentage of stock price trigger									98.00%
Threshold trading days | day									5
Threshold consecutive trading days | day									10
Senior Indebtedness
Debt Instrument [Line Items]
Debt instrument, unamortized discount													$ 10,500,000
Gross long-term debt including current maturities	7,956,600,000			6,727,000,000.0	7,956,600,000				$ 7,956,600,000
Senior Indebtedness | 2017 Senior Convertible Debt
Debt Instrument [Line Items]
Debt instrument, face amount						$ 643,900,000
Senior Indebtedness | 2015 Senior Convertible Debt
Debt Instrument [Line Items]
Extinguishment of debt, amount			383,300,000
Senior Indebtedness | 2020 Senior Convertible Debt
Debt Instrument [Line Items]
Debt issuance costs, including equity portion, gross	10,800,000
Debt issuance costs, gross	9,000,000.0				9,000,000.0				9,000,000.0
Equity portion of convertible debt issuance costs	1,800,000
Debt instrument, unamortized discount	110,000,000.0				110,000,000.0				110,000,000.0
Capped options indexed to equity, costs	35,800,000
Senior Indebtedness | 2.670% 2023 Notes
Debt Instrument [Line Items]
Debt instrument, unamortized discount	$ 2,500,000			0	$ 2,500,000				$ 2,500,000
Debt instrument, face amount												$ 1,000,000,000.00
Coupon Interest Rate	2.67%				2.67%				2.67%			2.67%
Gross long-term debt including current maturities	$ 1,000,000,000.0			0	$ 1,000,000,000.0				$ 1,000,000,000.0
Senior Indebtedness | 0.972% 2024 Notes
Debt Instrument [Line Items]
Debt instrument, redemption price (percent)									101.00%
Debt instrument, unamortized discount	4,100,000			0	4,100,000				$ 4,100,000		$ 4,200,000
Debt instrument, face amount	$ 1,400,000,000				$ 1,400,000,000				$ 1,400,000,000
Coupon Interest Rate	0.972%				0.972%				0.972%
Gross long-term debt including current maturities	$ 1,400,000,000.0			0	$ 1,400,000,000.0				$ 1,400,000,000.0
Senior Indebtedness | Debt Instrument, Redemption, Period One | 0.972% 2024 Notes
Debt Instrument [Line Items]
Debt instrument, redemption price (percent)	100.00%
Bridge Loan Facility
Debt Instrument [Line Items]
Extinguishment of debt, amount			615,000,000.0
Gain (loss) on settlement of debt			$ (5,300,000)
Debt instrument, unamortized discount	$ 0			3,100,000	0				0
Gross long-term debt including current maturities	$ 0			$ 615,000,000.0	$ 0				$ 0