Long-term Debt and Interest Expense (Components Of Long-Term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Principal amount of Convertible Notes	$ 3,548	$ 2,300
Issuance costs and discounts	(248)	(11)
Total debt	3,300	2,289
Less current portion of long-term debt	140	450
Long-term Debt, Excluding Current Maturities	$ 3,160	1,839
0.075
Debt Instrument [Line Items]
Senior notes, interest rate	7.50%
Principal amount of Convertible Notes	$ 0	450
3.45% senior notes due 2021
Debt Instrument [Line Items]
Senior notes, interest rate	3.45%
Principal amount of Convertible Notes	$ 140	500
3.95% senior notes due 2022
Debt Instrument [Line Items]
Senior notes, interest rate	3.95%
Principal amount of Convertible Notes	$ 244	600
0.25% convertible senior notes due 2025
Debt Instrument [Line Items]
Senior notes, interest rate	0.25%
Principal amount of Convertible Notes		0
4.45% senior notes due 2026
Debt Instrument [Line Items]
Senior notes, interest rate	4.45%
Principal amount of Convertible Notes	$ 500	500
7.20% senior notes due 2028
Debt Instrument [Line Items]
Senior notes, interest rate	7.20%
Principal amount of Convertible Notes	$ 241	250
1.90% senior notes due 2030
Debt Instrument [Line Items]
Senior notes, interest rate	1.90%
Principal amount of Convertible Notes	$ 1,100	$ 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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