Financial Instruments - Fair Value Measurements (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2016	Jun. 30, 2017	Dec. 31, 2016
Financial assets and financial liabilities measured at fair value on a recurring basis:
Pre-tax impairment charge related to certain property, plant and equipment	$ 252
Debt securities - noncurrent		$ 10	$ 8
Available-for-sale equity investments		6	7
Derivative assets		856	1,126
Derivative liabilities		304	206
Potential reduction in net position of total derivative assets		221	116
Fair value assets, Level 2 to Level 1 transfer		0	0
Fair value assets, Level 1 to Level 2 transfer		0	0
Fair value liabilities, Level 2 to Level 1 transfer		0	0
Fair value liabilities, Level 1 to Level 2 transfer		0	0
Recurring
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents		8,884	4,832
Debt securities - current		599	699
Debt securities - noncurrent		10	8
Available-for-sale equity investments		6	7
Derivative assets		856	1,126
Total Assets		10,355	6,672
Total Liabilities		304	206
Potential reduction in net position of total derivative assets		221	116
Potential reduction in net position of total derivative liabilities		221	116
Recurring \| Prepaid expenses and other current assets
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets		207	532
Recurring \| Investments and sundry assets
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets		649	594
Recurring \| Other accrued expenses and liabilities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative liabilities		298	145
Recurring \| Other liabilities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative liabilities		6	61
Recurring \| Interest rate contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets		557	555
Derivative liabilities		3	8
Recurring \| Foreign exchange contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets		297	560
Derivative liabilities		294	188
Recurring \| Equity contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets		2	11
Derivative liabilities		7	10
Recurring \| Time deposits and certificates of deposit
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents		7,285	3,629
Recurring \| Money market funds
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents		1,368	1,204
Recurring \| Canadian government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents		231
Recurring \| Level 1
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents		1,368	1,204
Debt securities - noncurrent		4	1
Available-for-sale equity investments		6	7
Total Assets		1,378	1,212
Recurring \| Level 1 \| Money market funds
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents		1,368	1,204
Recurring \| Level 2
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents		7,516	3,629
Debt securities - current		599	699
Debt securities - noncurrent		6	6
Derivative assets		856	1,126
Total Assets		8,977	5,460
Total Liabilities		304	206
Recurring \| Level 2 \| Interest rate contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets		557	555
Derivative liabilities		3	8
Recurring \| Level 2 \| Foreign exchange contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets		297	560
Derivative liabilities		294	188
Recurring \| Level 2 \| Equity contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets		2	11
Derivative liabilities		7	10
Recurring \| Level 2 \| Time deposits and certificates of deposit
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents		7,285	$ 3,629
Recurring \| Level 2 \| Canadian government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents		$ 231

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
-SubTopic 10
-Section 50
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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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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and elected not to be offset.

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Fair value of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be offset, deducted from derivative assets.

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and elected not to be offset.

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Fair value of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be offset, deducted from derivative liabilities.

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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 transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

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Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

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Amount of transfers of liabilities measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

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Amount of transfers of liabilities measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

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Fair value of financial and nonfinancial obligations.

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The charge against earnings resulting from the aggregate write down of tangible assets from their carrying value to their fair value.

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