Debt - Repayments of Principal and Interest (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014
Debt Instrument [Line Items]
Repayments of interest In 2015	$ 955
Repayments of interest In 2016	772
Repayments of interest In 2017	399
Repayments of interest In 2018	205
Repayments of interest In 2019	117
Repayments of interest thereafter	199
Interest Payable	2,647
Total repayments in 2015	15,446
Total repayments in 2016	9,949
Total repayments in 2017	7,654
Total repayments in 2018	2,871
Total repayments in 2019	1,977
Total repayments thereafter	2,199
Total repayments of principal and interest	40,096acf_RepaymentsofPrincipalandInterest
Secured Debt [Member]
Debt Instrument [Line Items]
Repayments of principal in 2015	11,880
Repayments of principal in 2016	7,296
Repayments of principal in 2017	4,353
Repayments of principal in 2018	1,331
Repayments of principal in 2019	371
Repayments of principal thereafter	0
Long-term Debt	25,231
Unsecured Debt [Member]
Debt Instrument [Line Items]
Repayments of principal in 2015	2,611
Repayments of principal in 2016	1,881
Repayments of principal in 2017	2,902
Repayments of principal in 2018	1,335
Repayments of principal in 2019	1,489
Repayments of principal thereafter	2,000
Long-term Debt	$ 12,218

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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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.

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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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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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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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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 second 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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