Disclosures About Fair Value Measurements (Financial Assets and Liabilities Not Carried At Fair Value) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Disclosure Item Amounts [Domain]
Fair Value Assets and Liabilities Not Carried At Fair Value [Line Items]
Short-term investments	$ 0	$ 441
Current portion of long-term debt	450	0
Long-term debt	1,839	2,284
Cash and cash equivalents	631	825
Cash and Cash Equivalents, Fair Value Disclosure	631	825
Short-term investments	0	443
Long-term investments	0	125
Reported Value Measurement [Member]
Fair Value Assets and Liabilities Not Carried At Fair Value [Line Items]
Short-term investments	0	443
Estimate of Fair Value Measurement [Member]
Fair Value Assets and Liabilities Not Carried At Fair Value [Line Items]
Current portion of long-term debt	451	0
Long-term debt	1,995	2,374
Cash
Fair Value Assets and Liabilities Not Carried At Fair Value [Line Items]
Cash and cash equivalents	631	775
Cash and Cash Equivalents, Fair Value Disclosure	631	775
Bank Time Deposits [Member]
Fair Value Assets and Liabilities Not Carried At Fair Value [Line Items]
Cash and cash equivalents	0	50
Cash and Cash Equivalents, Fair Value Disclosure	0	50
Commercial Paper [Member] \| Fair Value, Disclosure Item Amounts [Domain]
Fair Value Assets and Liabilities Not Carried At Fair Value [Line Items]
Short-term investments	0	53
Commercial Paper [Member] \| Reported Value Measurement [Member]
Fair Value Assets and Liabilities Not Carried At Fair Value [Line Items]
Short-term investments	0	53
Corporate Bond Securities [Member] \| Fair Value, Disclosure Item Amounts [Domain]
Fair Value Assets and Liabilities Not Carried At Fair Value [Line Items]
Short-term investments	0	288
Long-term investments	0	125
Corporate Bond Securities [Member] \| Reported Value Measurement [Member]
Fair Value Assets and Liabilities Not Carried At Fair Value [Line Items]
Short-term investments	0	290
Long-term investments	0	125
Bank Time Deposits [Member] \| Fair Value, Disclosure Item Amounts [Domain]
Fair Value Assets and Liabilities Not Carried At Fair Value [Line Items]
Short-term investments	0	100
Bank Time Deposits [Member] \| Reported Value Measurement [Member]
Fair Value Assets and Liabilities Not Carried At Fair Value [Line Items]
Short-term investments	$ 0	$ 100

[Line Items] for Fair Value Assets and Liabilities Not Carried At Fair Value [Table]

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
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-Section S99
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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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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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The total amount of investments that are intended to be held for an extended period of time (longer than one operating cycle).

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Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current.

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