Debt - Long Term Debt (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total debt	$ 15,312	$ 15,498
Commercial paper	600	0
Less: unamortized discounts and issuance costs	(1,208)	(1,235)
Total debt, net	14,104	14,263
Less: current portion	(1,500)	(750)
Long-term debt, net	$ 12,604	$ 13,513
1.85% due 2018
Debt Instrument [Line Items]
Interest rate	1.85%	1.85%
Long-term debt maturity year	2018
Total debt	$ 0	$ 750
4.25% due 2019
Debt Instrument [Line Items]
Interest rate	4.25%
Long-term debt maturity year	2019
Total debt	$ 900	900
2.50% due 2020
Debt Instrument [Line Items]
Interest rate	2.50%
Long-term debt maturity year	2020
Total debt	$ 1,250	1,250
3.35% due 2021
Debt Instrument [Line Items]
Interest rate	3.35%
Long-term debt maturity year	2021
Total debt	$ 900	900
3.10% due 2023
Debt Instrument [Line Items]
Interest rate	3.10%
Long-term debt maturity year	2023
Total debt	$ 500	500
2.90% due 2025
Debt Instrument [Line Items]
Interest rate	2.90%
Long-term debt maturity year	2025
Total debt	$ 750	750
3.55% due 2026
Debt Instrument [Line Items]
Interest rate	3.55%
Long-term debt maturity year	2026
Total debt	$ 2,000	2,000
3.60% due 2035
Debt Instrument [Line Items]
Interest rate	3.60%
Long-term debt maturity year	2035
Total debt	$ 500	500
4.50% and 6.15% due 2036
Debt Instrument [Line Items]
Long-term debt maturity year	2036
Total debt	$ 1,054	1,054
4.50% and 6.15% due 2036 \| Minimum
Debt Instrument [Line Items]
Interest rate	4.50%
4.50% and 6.15% due 2036 \| Maximum
Debt Instrument [Line Items]
Interest rate	6.15%
4.07% due 2042
Debt Instrument [Line Items]
Interest rate	4.07%
Long-term debt maturity year	2042
Total debt	$ 1,336	1,336
3.80% due 2045
Debt Instrument [Line Items]
Interest rate	3.80%
Long-term debt maturity year	2045
Total debt	$ 1,000	1,000
4.70% due 2046
Debt Instrument [Line Items]
Interest rate	4.70%
Long-term debt maturity year	2046
Total debt	$ 1,326	1,326
4.09% due 2052
Debt Instrument [Line Items]
Interest rate	4.09%
Long-term debt maturity year	2052
Total debt	$ 1,578	1,578
Other notes with rates from 4.85% to 8.50%, due 2023 to 2041
Debt Instrument [Line Items]
Total debt	$ 1,618	$ 1,654
Other notes with rates from 4.85% to 8.50%, due 2023 to 2041 \| Minimum
Debt Instrument [Line Items]
Interest rate	4.85%
Long-term debt maturity year	2023
Other notes with rates from 4.85% to 8.50%, due 2023 to 2041 \| Maximum
Debt Instrument [Line Items]
Interest rate	8.50%
Long-term debt maturity year	2041

Year the debt instrument matures.

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- Definition

Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

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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.

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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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No definition available.

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- Definition

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

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- Definition

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

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- Definition

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.

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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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