Commitments - Extended Warranty Liability (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Movement in deferred income
Amortization of deferred revenue	$ (3,800)	$ (8,000)
Current portion	10,704	10,704		$ 11,493	$ 11,552
Noncurrent portion	3,507	3,507		$ 3,758	$ 3,746
Extended Warranty
Movement in deferred income
Beginning Balance		566	$ 531
Revenue deferred for new extended warranty contracts		138	175
Amortization of deferred revenue		(178)	(198)
Other		(12)	24
Ending Balance	514	514	533
Current portion	242	242	258
Noncurrent portion	$ 273	$ 273	$ 275

Increase in contract with customer liability for new contracts.

No definition available.

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- Definition

Increase (decrease) in contract with customer liability for other changes not specified in the taxonomy, including foreign currency translation adjustments.

+ References

No definition available.

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- References

No definition available.

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- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

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- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as noncurrent.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

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