Debt (Long-Term Debt) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Long-Term Debt
Unamortized discount for the Notes above	$ (40)	$ (42)
Subtotal	3,960	3,958
Total future finance lease payments	1,154	685
Less: imputed interest for finance leases	(98)	(89)
Total long-term debt	5,016	4,554
3.625% Notes due on May 19, 2021
Long-Term Debt
Long-term debt	$ 1,000	1,000
Long-term debt, interest rate	3.625%
3.375% Notes due on February 25, 2024
Long-Term Debt
Long-term debt	$ 1,000	1,000
Long-term debt, interest rate	3.375%
1.998% Notes due on August 15, 2026
Long-Term Debt
Long-term debt	$ 2,000	$ 2,000
Long-term debt, interest rate	1.998%

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

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Amount, after accumulated amortization, of debt discount.

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Present value of lessee's discounted obligation for lease payments from finance lease, classified as noncurrent.

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

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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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