Commercial Paper and Long-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Par Value	$ 29,102	$ 33,022
Carrying Value	28,838	32,770
Fair Value	31,565	34,728
Commercial Paper [Member]
Debt Instrument [Line Items]
Par Value	304	3,633
Carrying Value	303	3,633
Fair Value	303	3,633
Floating rate notes due January 2017 [Member]
Debt Instrument [Line Items]
Par Value	0	750
Unsecured Debt, Current	0	750
Fair Value	$ 0	750
6.000% notes due June 2017 [Member]
Debt Instrument [Line Items]
Interest Rate	6.00%
Par Value	$ 0	441
Unsecured Debt, Current	0	446
Fair Value	$ 0	450
1.450% notes due July 2017 [Member]
Debt Instrument [Line Items]
Interest Rate	1.45%
Par Value	$ 0	750
Unsecured Debt, Current	0	750
Fair Value	$ 0	751
1.400% notes due October 2017 [Member]
Debt Instrument [Line Items]
Interest Rate	1.40%
Par Value	$ 625	625
Unsecured Debt, Current	625	624
Fair Value	$ 625	626
6.000% notes due November 2017 [Member]
Debt Instrument [Line Items]
Interest Rate	6.00%
Par Value	$ 156	156
Unsecured Debt, Current	157	159
Fair Value	$ 157	163
1.400% notes due December 2017 [Member]
Debt Instrument [Line Items]
Interest Rate	1.40%
Par Value	$ 750	750
Unsecured Debt, Current	750	751
Fair Value	$ 750	750
6.000% notes due February 2018 [Member]
Debt Instrument [Line Items]
Interest Rate	6.00%
Par Value	$ 1,100	1,100
Unsecured Long-term Debt, Noncurrent		1,107
Unsecured Debt, Current	1,102
Fair Value	$ 1,118	1,153
1.900% notes due July 2018 [Member]
Debt Instrument [Line Items]
Interest Rate	1.90%
Par Value	$ 1,500	1,500
Unsecured Long-term Debt, Noncurrent		1,496
Unsecured Debt, Current	1,498
Fair Value	$ 1,504	1,507
1.700% Notes due February 2019 [Member]
Debt Instrument [Line Items]
Interest Rate	1.70%
Par Value	$ 750	750
Unsecured Long-term Debt, Noncurrent	749	748
Fair Value	$ 750	748
1.625% notes due March 2019 [Member]
Debt Instrument [Line Items]
Interest Rate	1.625%
Par Value	$ 500	500
Unsecured Long-term Debt, Noncurrent	501	501
Fair Value	$ 499	498
2.300% notes due December 2019 [Member]
Debt Instrument [Line Items]
Interest Rate	2.30%
Par Value	$ 500	500
Unsecured Long-term Debt, Noncurrent	497	498
Fair Value	$ 504	504
2.700% notes due July 2020 [Member]
Debt Instrument [Line Items]
Interest Rate	2.70%
Par Value	$ 1,500	1,500
Unsecured Long-term Debt, Noncurrent	1,496	1,495
Fair Value	$ 1,530	1,523
3.875% notes due October 2020 [Member]
Debt Instrument [Line Items]
Interest Rate	3.875%
Par Value	$ 450	450
Unsecured Long-term Debt, Noncurrent	449	450
Fair Value	$ 473	474
4.700% notes due February 2021 [Member]
Debt Instrument [Line Items]
Interest Rate	4.70%
Par Value	$ 400	400
Unsecured Long-term Debt, Noncurrent	407	409
Fair Value	$ 431	433
2.125% notes due March 2021 [Member]
Debt Instrument [Line Items]
Interest Rate	2.125%
Par Value	$ 750	750
Unsecured Long-term Debt, Noncurrent	746	745
Fair Value	$ 750	741
3.375% notes due November 2021 [Member]
Debt Instrument [Line Items]
Interest Rate	3.375%
Par Value	$ 500	500
Unsecured Long-term Debt, Noncurrent	497	497
Fair Value	$ 520	519
2.875% notes due December 2021 [Member]
Debt Instrument [Line Items]
Interest Rate	2.875%
Par Value	$ 750	750
Unsecured Long-term Debt, Noncurrent	748	748
Fair Value	$ 769	760
2.875% notes due March 2022 [Member]
Debt Instrument [Line Items]
Interest Rate	2.875%
Par Value	$ 1,100	1,100
Unsecured Long-term Debt, Noncurrent	1,063	1,057
Fair Value	$ 1,125	1,114
3.350% notes due July 2022 [Member]
Debt Instrument [Line Items]
Interest Rate	3.35%
Par Value	$ 1,000	1,000
Unsecured Long-term Debt, Noncurrent	996	995
Fair Value	$ 1,044	1,030
0.000% notes due November 2022 [Member]
Debt Instrument [Line Items]
Interest Rate	0.00%
Par Value	$ 15	15
Unsecured Long-term Debt, Noncurrent	11	11
Fair Value	$ 12	12
2.750% notes due February 2023 [Member]
Debt Instrument [Line Items]
Interest Rate	2.75%
Par Value	$ 625	625
Unsecured Long-term Debt, Noncurrent	612	609
Fair Value	$ 632	622
2.875% notes due March 2023 [Member]
Debt Instrument [Line Items]
Interest Rate	2.875%
Par Value	$ 750	750
Unsecured Long-term Debt, Noncurrent	771	771
Fair Value	$ 765	753
3.750% notes due July 2025 [Member]
Debt Instrument [Line Items]
Interest Rate	3.75%
Par Value	$ 2,000	2,000
Unsecured Long-term Debt, Noncurrent	1,987	1,986
Fair Value	$ 2,122	2,070
3.100% notes due March 2026 [Member]
Debt Instrument [Line Items]
Interest Rate	3.10%
Par Value	$ 1,000	1,000
Unsecured Long-term Debt, Noncurrent	995	994
Fair Value	$ 1,012	986
3.450% notes due January 2027 [Member]
Debt Instrument [Line Items]
Interest Rate	3.45%
Par Value	$ 750	750
Unsecured Long-term Debt, Noncurrent	745	745
Fair Value	$ 776	762
3.375% notes due April 2027 [Member]
Debt Instrument [Line Items]
Interest Rate	3.75%
Par Value	$ 625	0
Unsecured Long-term Debt, Noncurrent	618	0
Fair Value	$ 643	0
4.625% notes due July 2035 [Member]
Debt Instrument [Line Items]
Interest Rate	4.625%
Par Value	$ 1,000	1,000
Unsecured Long-term Debt, Noncurrent	991	991
Fair Value	$ 1,146	1,090
5.800% notes due March 2036 [Member]
Debt Instrument [Line Items]
Interest Rate	5.80%
Par Value	$ 850	850
Unsecured Long-term Debt, Noncurrent	837	837
Fair Value	$ 1,071	1,034
6.500% notes due June 2037 [Member]
Debt Instrument [Line Items]
Interest Rate	6.50%
Par Value	$ 500	500
Unsecured Long-term Debt, Noncurrent	491	491
Fair Value	$ 683	643
6.625% notes due November 2037 [Member]
Debt Instrument [Line Items]
Interest Rate	6.625%
Par Value	$ 650	650
Unsecured Long-term Debt, Noncurrent	641	640
Fair Value	$ 903	850
6.875% notes due February 2038 [Member]
Debt Instrument [Line Items]
Interest Rate	6.875%
Par Value	$ 1,100	1,100
Unsecured Long-term Debt, Noncurrent	1,075	1,075
Fair Value	$ 1,561	1,497
5.700% notes due October 2040 [Member]
Debt Instrument [Line Items]
Interest Rate	5.70%
Par Value	$ 300	300
Unsecured Long-term Debt, Noncurrent	296	296
Fair Value	$ 383	366
5.950% notes due February 2041 [Member]
Debt Instrument [Line Items]
Interest Rate	5.95%
Par Value	$ 350	350
Unsecured Long-term Debt, Noncurrent	345	345
Fair Value	$ 460	437
4.625% notes due November 2041 [Member]
Debt Instrument [Line Items]
Interest Rate	4.625%
Par Value	$ 600	600
Unsecured Long-term Debt, Noncurrent	588	588
Fair Value	$ 673	634
4.375% notes due March 2042 [Member]
Debt Instrument [Line Items]
Interest Rate	4.375%
Par Value	$ 502	502
Unsecured Long-term Debt, Noncurrent	483	483
Fair Value	$ 543	509
3.950% notes due October 2042 [Member]
Debt Instrument [Line Items]
Interest Rate	3.95%
Par Value	$ 625	625
Unsecured Long-term Debt, Noncurrent	607	606
Fair Value	$ 641	609
4.250% notes due March 2043 [Member]
Debt Instrument [Line Items]
Interest Rate	4.25%
Par Value	$ 750	750
Unsecured Long-term Debt, Noncurrent	734	734
Fair Value	$ 801	765
4.750% notes due July 2045 [Member]
Debt Instrument [Line Items]
Interest Rate	4.75%
Par Value	$ 2,000	2,000
Unsecured Long-term Debt, Noncurrent	1,972	1,972
Fair Value	$ 2,310	2,203
4.200% notes due January 2047 [Member]
Debt Instrument [Line Items]
Interest Rate	4.20%
Par Value	$ 750	750
Unsecured Long-term Debt, Noncurrent	738	737
Fair Value	$ 799	759
4.250% notes due April 2047 [Member]
Debt Instrument [Line Items]
Interest Rate	4.25%
Par Value	$ 725	0
Unsecured Long-term Debt, Noncurrent	717	0
Fair Value	$ 777	$ 0

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.

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)(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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- Definition

Face (par) amount of debt instrument at time of issuance.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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- Definition

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

+ References

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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.

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

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- Definition

Carrying value as of the balance sheet date of the portion of long-term, uncollateralized debt obligations due within one year or the normal operating cycle, if longer.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Carrying value as of the balance sheet date of uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

+ References

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