Debt (Scheduled Remaining Maturity of Long-term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
2017	$ 14,553
2018	11,755
2019	8,976
2020	6,421
2021	3,076
2022 and thereafter	9,032
Derivative, Amount of Hedged Item	315	$ 331
Long-term debt	54,128	66,234
Derivative Instrument Converting Fixed-rate Debt into Variable-rate Obligations	2,100
Derivative Instrument Converting Variable-rate Debt into Fixed-rate Obligations	132
Unsecured Debt [Member]
Debt Instrument [Line Items]
2017	4,274
2018	3,599
2019	1,642
2020	2,173
2021	595
2022 and thereafter	7,441
Derivative, Amount of Hedged Item	326	334
Long-term debt	20,050	20,966
Debt Instrument, Unamortized Discount	(91)
Debt Instrument, Unamortized Discount	(1,326)
Unsecured Debt [Member] \| Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount, Noncurrent	(101)
Unsecured Debt [Member] \| Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount, Noncurrent	(39)
Unsecured Debt [Member] \| Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount, Noncurrent	(39)
Unsecured Debt [Member] \| Debt Instrument, Redemption, Period Four [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount, Noncurrent	(43)
Unsecured Debt [Member] \| Debt Instrument, Redemption, Period Five [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount, Noncurrent	(1,013)
Secured Debt [Member]
Debt Instrument [Line Items]
2017	10,279
2018	8,156
2019	7,334
2020	4,248
2021	2,481
2022 and thereafter	1,591
Derivative, Amount of Hedged Item	(11)	(3)
Long-term debt	34,078	$ 45,268
Long-term Debt [Member] \| Unsecured Debt [Member]
Debt Instrument [Line Items]
2017	4,365
2018	3,700
2019	1,681
2020	2,212
2021	638
2022 and thereafter	8,454
Derivative, Amount of Hedged Item	326
Long-term debt	21,376
original issue discount [Member] \| Unsecured Debt [Member]
Debt Instrument [Line Items]
Derivative, Amount of Hedged Item	$ 0

Derivative Instrument Converting Fixed-rate Debt into Variable-rate Obligations

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- Definition

Derivative Instrument Converting Variable-rate Debt into Fixed-rate Obligations

+ References

No definition available.

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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, after accumulated amortization, of debt discount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

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Amount of debt discount to be amortized within one year or within the normal operating cycle, if longer.

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Amount of debt discount to be amortized after one year or the normal operating cycle, if longer.

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- Definition

Amount of the hedged item as of the balance sheet date related to the derivative. For example, the hedged balance on a debt instrument.

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No definition available.

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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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 210
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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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