Debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Lease financing obligations	$ 0	$ 1
Debt issuance costs	0	(1)
Total, current portion	18	241
Debt issuance costs	(7)	(10)
Total, non-current portion	$ 1,237	1,020
1.125% Convertible Notes
Debt Instrument [Line Items]
Percentage of contractual interest rate	1.125%
5.375% Notes
Debt Instrument [Line Items]
Percentage of contractual interest rate	5.375%
4.875% Notes
Debt Instrument [Line Items]
Percentage of contractual interest rate	4.875%
Convertible Debt \| 1.125% Convertible Notes
Debt Instrument [Line Items]
Percentage of contractual interest rate	1.125%
Current portion of long-term debt	$ 12	241
Convertible Debt \| 4.875% Notes
Debt Instrument [Line Items]
Percentage of contractual interest rate	4.875%
Senior Notes \| 1.125% Convertible Notes
Debt Instrument [Line Items]
Percentage of contractual interest rate	1.125%
Senior Notes \| 5.375% Notes
Debt Instrument [Line Items]
Percentage of contractual interest rate	5.375%
Non-current portion of long-term debt	$ 700	700
Senior Notes \| 4.875% Notes
Debt Instrument [Line Items]
Percentage of contractual interest rate	4.875%
Non-current portion of long-term debt	$ 330	330
Term Loan Facility \| Term Loan Facility
Debt Instrument [Line Items]
Current portion of long-term debt	6	0
Non-current portion of long-term debt	$ 214	$ 0

Long-Term Debt, Current Maturities, Net Of Unamortized Premium (Discount)

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Long-Term Debt, Noncurrent, Net Of Unamortized Debt Discount

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Amount of capital lease obligation due within one year or the normal operating cycle, if longer.

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

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

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

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Amount of long-term debt and lease obligation, classified as current.

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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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