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Debt Instrument, Convertible, Principal Amount Exercised

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Debt Instrument, Convertible, Terms Of Conversion Feature, Conversion Amount

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Line of Credit Facility, Maximum Borrowing Capacity, Option to Increase, Amount

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Payments for Repurchase of Convertible Notes

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Exercise price per share or per unit of warrants or rights outstanding.

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The number of shares issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or payments in the period.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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The price per share of the conversion feature embedded in the debt instrument.

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Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount.

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Threshold period of specified consecutive trading days within which common stock price to conversion price of convertible debt instrument must exceed threshold percentage for specified number of trading days to trigger conversion feature.

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Minimum percentage of common stock price to conversion price of convertible debt instruments to determine eligibility of conversion.

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Face (par) amount of debt instrument at time of issuance.

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

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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Amount, after accumulated amortization, of debt discount.

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The amount of the liability for the conversion option reclassified to stockholders' equity when the embedded option no longer required separation from the host instrument.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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The cash inflow from the issuance of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

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Debt - Narrative (Details)		1 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended
Debt - Narrative (Details)	Jun. 29, 2020	May 31, 2020 USD ($) $ / shares shares	Nov. 30, 2018 USD ($) d $ / shares shares	Jun. 30, 2017 USD ($)	Sep. 30, 2020 USD ($) shares	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) d shares	Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2019 USD ($)	Dec. 19, 2018 USD ($)	Sep. 30, 2017 USD ($) $ / shares
Debt Instrument [Line Items]
Proceeds from issuance of convertible notes, net of issuance costs							$ 1,188,800,000	$ 0
Payments to repurchase convertible notes		$ 282,600,000					282,600,000	0
Loss on extinguishment of debt					$ 500,000	$ 0	5,900,000	$ 0
Equity component of 2025 Notes issuance, net of issuance costs							289,400,000
Senior Notes
Debt Instrument [Line Items]
Principal amount					2,057,500,000		2,057,500,000				$ 1,250,000,000.0
Conversion amount					1,000		$ 1,000
Redemption price (as a percent)							100.00%
Unamortized debt discount					391,400,000		$ 391,400,000				177,200,000
Unamortized debt issuance costs					20,300,000		20,300,000				13,100,000
Senior Notes \| Senior Convertible Notes due 2023
Debt Instrument [Line Items]
Principal amount			$ 850,000,000.0		$ 850,000,000.0		$ 850,000,000.0				850,000,000.0
Interest rate on convertible notes (as a percent)			0.75%
Proceeds from issuance of convertible notes, net of issuance costs			$ 836,600,000
Conversion ratio			0.0060869
Conversion amount			$ 1,000
Conversion price of convertible notes (USD per share) \| $ / shares			$ 164.29
Holder's repurchase price percentage in event of fundamental change (as a percent)					100.00%		100.00%
Number of trading days \| d			60
Proportion of conversion price (as a percent)							130.00%
Redemption price (as a percent)							100.00%
Stock counterparties to acquire with warrants purchased (shares) \| shares			5,200,000
Proceeds from sale of warrants			$ 183,800,000
Exercise price of warrants or rights (USD per share) \| $ / shares			$ 198.38
Senior Notes \| Senior Convertible Notes due 2022
Debt Instrument [Line Items]
Principal amount		260,000,000.0			$ 0		$ 0				400,000,000.0		$ 400,000,000.0
Interest rate on convertible notes (as a percent)													0.75%
Proceeds from issuance of convertible notes, net of issuance costs				$ 389,000,000.0
Conversion ratio				0.0100918
Conversion price of convertible notes (USD per share) \| $ / shares													$ 99.09
Holder's repurchase price percentage in event of fundamental change (as a percent)					100.00%		100.00%
Proportion of conversion price (as a percent)							140.00%
Redemption price (as a percent)	100.00%
Principal amount of exercised options to covert							$ 140,000,000.0
Senior Notes \| Senior Convertible Notes due 2025
Debt Instrument [Line Items]
Principal amount		$ 1,210,000,000			$ 1,207,500,000		$ 1,207,500,000				$ 0
Interest rate on convertible notes (as a percent)		0.25%
Proceeds from issuance of convertible notes, net of issuance costs		$ 1,190,000,000
Conversion ratio		0.0016655
Conversion price of convertible notes (USD per share) \| $ / shares		$ 600.42
Holder's repurchase price percentage in event of fundamental change (as a percent)					100.00%		100.00%
Proportion of conversion price (as a percent)							130.00%
Senior Notes \| Senior Convertible Notes due 2025 \| Maximum
Debt Instrument [Line Items]
Conversion ratio		0.0023732
Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity of revolving credit agreement					$ 200,000,000.0		$ 200,000,000.0					$ 200,000,000.0
Option to increase revolving line of credit												$ 500,000,000.0
Value of unrestricted cash on hand threshold							$ 100,000,000.0
Line of Credit \| Minimum
Debt Instrument [Line Items]
Interest rate on convertible notes (as a percent)					0.375%		0.375%
Unused capacity fee (as a percent)							0.20%
Line of Credit \| Maximum
Debt Instrument [Line Items]
Interest rate on convertible notes (as a percent)					1.00%		1.00%
Unused capacity fee (as a percent)							0.30%
Additional Paid-In Capital
Debt Instrument [Line Items]
Equity component of 2025 Notes issuance, net of issuance costs							$ 289,400,000
Additional Paid-In Capital \| Senior Notes \| Senior Convertible Notes due 2023
Debt Instrument [Line Items]
Recognized additional paid-in capital from cash conversion option									$ 174,400,000
Additional Paid-In Capital \| Senior Notes \| Senior Convertible Notes due 2022
Debt Instrument [Line Items]
Recognized additional paid-in capital from cash conversion option										$ 72,600,000
Common Stock
Debt Instrument [Line Items]
Repurchase and conversions of 2022 Notes, net of tax (shares) \| shares					400,000		3,400,000
Common Stock \| Senior Notes
Debt Instrument [Line Items]
Repurchase and conversions of 2022 Notes, net of tax (shares) \| shares		1,953,067
Common Stock \| Senior Notes \| Senior Convertible Notes due 2022
Debt Instrument [Line Items]
Repurchase and conversions of 2022 Notes, net of tax (shares) \| shares							1,412,497
Debt Instrument Conversion Term One \| Senior Notes \| Senior Convertible Notes due 2023 \| Minimum
Debt Instrument [Line Items]
Number of trading days \| d							20
Proportion of applicable conversion price (as a percent)							130.00%
Debt Instrument Conversion Term One \| Senior Notes \| Senior Convertible Notes due 2023 \| Maximum
Debt Instrument [Line Items]
Number of trading days \| d							30
Debt Instrument Conversion Term One \| Senior Notes \| Senior Convertible Notes due 2022 \| Minimum
Debt Instrument [Line Items]
Number of trading days \| d							20
Proportion of applicable conversion price (as a percent)							130.00%
Debt Instrument Conversion Term One \| Senior Notes \| Senior Convertible Notes due 2022 \| Maximum
Debt Instrument [Line Items]
Number of trading days \| d							30
Debt Instrument Conversion Term One \| Senior Notes \| Senior Convertible Notes due 2025 \| Minimum
Debt Instrument [Line Items]
Number of trading days \| d							20
Proportion of applicable conversion price (as a percent)							130.00%
Debt Instrument Conversion Term One \| Senior Notes \| Senior Convertible Notes due 2025 \| Maximum
Debt Instrument [Line Items]
Number of trading days \| d							30
Debt Instrument Conversion Term Two \| Senior Notes \| Senior Convertible Notes due 2023
Debt Instrument [Line Items]
Number of trading days \| d							5
Debt Instrument Conversion Term Two \| Senior Notes \| Senior Convertible Notes due 2023 \| Maximum
Debt Instrument [Line Items]
Number of trading days \| d							5
Proportion of applicable conversion price (as a percent)							98.00%
Debt Instrument Conversion Term Two \| Senior Notes \| Senior Convertible Notes due 2022
Debt Instrument [Line Items]
Number of trading days \| d							5
Debt Instrument Conversion Term Two \| Senior Notes \| Senior Convertible Notes due 2022 \| Maximum
Debt Instrument [Line Items]
Number of trading days \| d							5
Proportion of applicable conversion price (as a percent)							98.00%
Debt Instrument Conversion Term Two \| Senior Notes \| Senior Convertible Notes due 2025
Debt Instrument [Line Items]
Number of trading days \| d							5
Debt Instrument Conversion Term Two \| Senior Notes \| Senior Convertible Notes due 2025 \| Maximum
Debt Instrument [Line Items]
Number of trading days \| d							5
Proportion of applicable conversion price (as a percent)							98.00%
Designated as Hedging Instrument \| Senior Notes \| Senior Convertible Notes due 2023
Debt Instrument [Line Items]
Stock issued upon conversion of senior notes (shares) \| shares			5,200,000
Equity component of 2025 Notes issuance, net of issuance costs			$ 218,900,000
Designated as Hedging Instrument \| Senior Notes \| Senior Convertible Notes due 2025
Debt Instrument [Line Items]
Recognized additional paid-in capital from cash conversion option							$ 289,400,000
London Interbank Offered Rate (LIBOR) \| Line of Credit \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)							1.375%
London Interbank Offered Rate (LIBOR) \| Line of Credit \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)							2.00%