Debt (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total debt principal	$ 13,191	$ 4,032
Less unamortized debt issuance costs and discounts	110	50
Total debt	13,081	3,982
Less current portion	1,678	2
Long-term debt	11,403	3,980
Commercial Paper
Debt Instrument [Line Items]
Short term debt	$ 1,672	0
Weighted average interest rate	2.114%
Fixed Rate Notes Due May 2020
Debt Instrument [Line Items]
Long term debt	$ 2,000	0
Interest rate	2.875%
Fixed Rate Notes Due May 2021
Debt Instrument [Line Items]
Long term debt	$ 2,000	0
Interest rate	3.00%
Fixed-Rate Notes Due July 2021
Debt Instrument [Line Items]
Long term debt	$ 500	500
Interest rate	3.875%
Fixed Rate Notes Due November 2022
Debt Instrument [Line Items]
Long term debt	$ 1,000	1,000
Interest rate	2.25%
Fixed Rate Notes Due May 2023
Debt Instrument [Line Items]
Long term debt	$ 750	0
Interest rate	3.375%
Fixed Rate Notes Due August 2023
Debt Instrument [Line Items]
Long term debt	$ 500	500
Interest rate	1.875%
Fixed Rate Notes Due November 2024
Debt Instrument [Line Items]
Long term debt	$ 500	500
Interest rate	2.375%
Fixed Rate Notes Due May 2025
Debt Instrument [Line Items]
Long term debt	$ 750	0
Interest rate	3.50%
Fixed Rate Notes Due August 2026
Debt Instrument [Line Items]
Long term debt	$ 500	500
Interest rate	2.125%
Fixed Rate Notes Due November 2027
Debt Instrument [Line Items]
Long term debt	$ 500	500
Interest rate	2.625%
Fixed Rate Notes Due May 2028
Debt Instrument [Line Items]
Long term debt	$ 1,000	0
Interest rate	3.75%
Fixed Rate Notes Due November 2042
Debt Instrument [Line Items]
Long term debt	$ 500	500
Interest rate	3.60%
Floating Rate Notes Due May 2020 \| LIBOR
Debt Instrument [Line Items]
Long term debt	$ 500	0
Basis spread on variable rate	0.29%
Floating Rate Notes Due May 2021 \| LIBOR
Debt Instrument [Line Items]
Long term debt	$ 500	0
Basis spread on variable rate	0.38%
Other Debt Securities
Debt Instrument [Line Items]
Long term debt	$ 19	$ 32
Other Interest rate	Various

Debt Instrument Interest Rate

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- Definition

Debt, Long-term and Short-term, Combined Amount, Excluding Current Maturities

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Debt, Long-term and Short-term, Combined Amount, Net

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- Definition

Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

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

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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- Definition

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

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- Definition

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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Amount of unamortized debt discount (premium) and debt issuance costs.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

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- Definition

Represents the aggregate of total long-term debt, including current maturities and short-term debt.

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Weighted average interest rate of short-term debt outstanding calculated at point in time.

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