Debt - Repayments of Principal and Interest (Details) $ in Millions	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Repayments of interest In 2016	$ 1,275
Repayments of interest In 2017	1,008
Repayments of interest In 2018	588
Repayments of interest In 2019	397
Repayments of interest In 2020	267
Repayments of interest thereafter	483
Interest Payable	4,018
Total repayments in 2016	20,068
Total repayments in 2017	13,830
Total repayments in 2018	9,735
Total repayments in 2019	4,682
Total repayments in 2020	4,694
Total repayments thereafter	5,533
Total repayments of principal and interest	58,542
Secured Debt [Member]
Debt Instrument [Line Items]
Repayments of principal in 2016	14,450
Repayments of principal in 2017	9,168
Repayments of principal in 2018	5,688
Repayments of principal in 2019	1,120
Repayments of principal in 2020	317
Repayments of principal thereafter	0
Long-term Debt	30,743
Unsecured Debt [Member]
Debt Instrument [Line Items]
Repayments of principal in 2016	4,343
Repayments of principal in 2017	3,654
Repayments of principal in 2018	3,459
Repayments of principal in 2019	3,165
Repayments of principal in 2020	4,110
Repayments of principal thereafter	5,050
Long-term Debt	$ 23,781

Amount of interest payments scheduled after the fifth fiscal year following the latest fiscal year.

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Amount of interest payments scheduled in the next fiscal year following the latest fiscal year.

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Amount of interest payments scheduled in the fifth fiscal year following the latest fiscal year.

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Amount of interest payments scheduled in the fourth fiscal year following the latest fiscal year.

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Amount of interest payments scheduled in the third fiscal year following the latest fiscal year.

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Amount of interest payments scheduled in the second fiscal year following the latest fiscal year.

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Amount of principal and interest payments scheduled after the fifth fiscal year following the latest fiscal year.

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Amount of principal and interest payments scheduled in the next fiscal year following the latest fiscal year.

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Amount of principal and interest payments scheduled in the fifth fiscal year following the latest fiscal year.

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Amount of principal and interest payments scheduled in the fourth fiscal year following the latest fiscal year.

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Amount of principal and interest payments scheduled in the third fiscal year following the latest fiscal year.

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Amount of principal and interest payments scheduled in the second fiscal year following the latest fiscal year.

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Repayments of Principal and Interest

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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 interest payable on debt, including, but not limited to, trade payables.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
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-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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-Publisher SEC
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-Paragraph 20, 22
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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
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-Section S99
-Paragraph 3
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-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690

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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 in the next 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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
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-Paragraph 3
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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 in 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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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 in the fourth 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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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 in the third 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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