Financial Instruments - Fair Value Measurements (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Financial assets and financial liabilities measured at fair value on a recurring basis:
Debt securities - noncurrent	$ 9	$ 8
Available-for-sale equity investments	11	192
Derivative assets	1,284	994
Potential reduction in net position of total derivative assets	280	139
Fair value assets, Level 2 to Level 1 transfer	0	0
Fair value assets, Level 1 to Level 2 transfer	0	0
Recurring
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	7,301	4,943
Debt securities - current	599	506
Debt securities - noncurrent	9	8
Trading security investments		28
Available-for-sale equity investments	11	192
Derivative assets	1,284	994
Total Assets	9,204	6,671
Total Liabilities	414	186
Potential reduction in net position of total derivative assets	280	139
Potential reduction in net position of total derivative liabilities	280	139
Recurring \| Prepaid expenses and other current assets
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	262	292
Recurring \| Investments and sundry assets
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	1,022	702
Recurring \| Other accrued expenses and liabilities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative liabilities	374	164
Recurring \| Other liabilities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative liabilities	40	22
Recurring \| Interest rate contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	1,015	656
Derivative liabilities		3
Recurring \| Foreign exchange contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	258	332
Derivative liabilities	406	164
Recurring \| Equity contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	11	6
Derivative liabilities	8	19
Recurring \| Time deposits and certificates of deposit
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	3,198	2,856
Recurring \| Money market funds
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	2,141	2,069
Recurring \| U.S. government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	1,500
Recurring \| Canadian government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	462
Recurring \| Other securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents		18
Recurring \| Level 1
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	2,141	2,069
Debt securities - noncurrent	1	1
Trading security investments		28
Available-for-sale equity investments	11	192
Total Assets	2,153	2,290
Recurring \| Level 1 \| Money market funds
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	2,141	2,069
Recurring \| Level 2
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	5,160	2,874
Debt securities - current	599	506
Debt securities - noncurrent	7	6
Derivative assets	1,284	994
Total Assets	7,051	4,381
Total Liabilities	414	186
Recurring \| Level 2 \| Interest rate contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	1,015	656
Derivative liabilities		3
Recurring \| Level 2 \| Foreign exchange contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	258	332
Derivative liabilities	406	164
Recurring \| Level 2 \| Equity contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	11	6
Derivative liabilities	8	19
Recurring \| Level 2 \| Time deposits and certificates of deposit
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	3,198	2,856
Recurring \| Level 2 \| U.S. government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	1,500
Recurring \| Level 2 \| Canadian government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	$ 462
Recurring \| Level 2 \| Other securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents		$ 18

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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Amount of investments in debt securities classified as available-for-sale, expected to be converted to cash, sold or exchanged 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
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Total of debt securities categorized neither as held-to-maturity nor trading which are intended be sold or mature more than one year from the balance sheet date or operating cycle, if longer.

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Equity securities categorized neither as held-to-maturity nor trading which are intended be sold more than one year from the balance sheet date or operating cycle, if longer.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=6506951

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

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Fair value of financial and nonfinancial obligations.

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Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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