Financial Instruments - Fair Value Measurements (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2016	Dec. 31, 2015
Financial assets and financial liabilities measured at fair value on a recurring basis:
Pre-tax impairment charge related to certain property, plant and equipment	$ 218
Debt securities - noncurrent	9	$ 8
Available-for-sale equity investments	12	192
Derivative assets	1,166	994
Potential reduction in net position of total derivative assets	185	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	5,974	4,943
Debt securities - current	929	506
Debt securities - noncurrent	9	8
Trading security investments		28
Available-for-sale equity investments	12	192
Derivative assets	1,166	994
Total Assets	8,090	6,671
Total Liabilities	286	186
Potential reduction in net position of total derivative assets	185	139
Potential reduction in net position of total derivative liabilities	185	139
Recurring \| Prepaid expenses and other current assets
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	198	292
Recurring \| Investments and sundry assets
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	967	702
Recurring \| Other accrued expenses and liabilities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative liabilities	282	164
Recurring \| Other liabilities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative liabilities	3	22
Recurring \| Interest rate contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	919	656
Derivative liabilities		3
Recurring \| Foreign exchange contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	245	332
Derivative liabilities	277	164
Recurring \| Equity contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	2	6
Derivative liabilities	9	19
Recurring \| Time deposits and certificates of deposit
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	1,948	2,856
Recurring \| Money market funds
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	2,237	2,069
Recurring \| U.S. government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	1,299
Recurring \| Canadian government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	456
Recurring \| Other securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	34	18
Recurring \| Level 1
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	2,237	2,069
Debt securities - noncurrent	1	1
Trading security investments		28
Available-for-sale equity investments	12	192
Total Assets	2,250	2,290
Recurring \| Level 1 \| Money market funds
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	2,237	2,069
Recurring \| Level 2
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	3,737	2,874
Debt securities - current	929	506
Debt securities - noncurrent	7	6
Derivative assets	1,166	994
Total Assets	5,840	4,381
Total Liabilities	286	186
Recurring \| Level 2 \| Interest rate contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	919	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	245	332
Derivative liabilities	277	164
Recurring \| Level 2 \| Equity contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	2	6
Derivative liabilities	9	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	1,948	2,856
Recurring \| Level 2 \| U.S. government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	1,299
Recurring \| Level 2 \| Canadian government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	456
Recurring \| Level 2 \| Other securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	$ 34	$ 18

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

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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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