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Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Significant Accounting Policies [Line Items]
Changes in assumptions and experience gains and losses	Greater than 10%
Period of benefit obligation in current liabilities	Next twelve months
Research and develepment costs	$ 522	$ 460
Minimum [Member]
Significant Accounting Policies [Line Items]
Amortizable intangible assets, estimated useful life	4 years
Minimum [Member] | Building [Member]
Significant Accounting Policies [Line Items]
Annual rates of depreciation on fixed assets	2.50%
Minimum [Member] | General Purpose Equipment [Member]
Significant Accounting Policies [Line Items]
Annual rates of depreciation on fixed assets	7.00%
Minimum [Member] | Special Purpose Equipment [Member]
Significant Accounting Policies [Line Items]
Annual rates of depreciation on fixed assets	10.00%
Maximum [Member]
Significant Accounting Policies [Line Items]
Amortizable intangible assets, estimated useful life	15 years
Maximum [Member] | Building [Member]
Significant Accounting Policies [Line Items]
Annual rates of depreciation on fixed assets	5.00%
Maximum [Member] | General Purpose Equipment [Member]
Significant Accounting Policies [Line Items]
Annual rates of depreciation on fixed assets	10.00%
Maximum [Member] | Special Purpose Equipment [Member]
Significant Accounting Policies [Line Items]
Annual rates of depreciation on fixed assets	33.00%

X

- Definition

Changes in assumptions and experience gains and losses recognized in income.

+ References

No definition available.

+ Details

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X

- Definition

Period of benefit obligation in current liabilities.

+ References

No definition available.

+ Details

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X

- Definition

Property plant and equipment depreciation rate.

+ References

No definition available.

+ Details

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X

- Definition

Significant Accounting Policies [Line Items]

+ References

No definition available.

+ Details

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- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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X

- Definition

The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

+ Details

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- Details

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- Details

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X

- Details

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X

- Details

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