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Investment Properties - Investment Properties Depreciated Using Straight-Line Method Over Their Estimated Useful Lives (Detail)	12 Months Ended
	Dec. 31, 2017
Bottom of range [member] | Main plant buildings [Member]
Disclosure of detailed information about investment property [line items]
Investment properties are depreciated using the straight-line method over their estimated useful lives	10 years
Bottom of range [member] | Other Investment Properties [Member]
Disclosure of detailed information about investment property [line items]
Investment properties are depreciated using the straight-line method over their estimated useful lives	3 years
Top of range [member] | Main plant buildings [Member]
Disclosure of detailed information about investment property [line items]
Investment properties are depreciated using the straight-line method over their estimated useful lives	40 years
Top of range [member] | Other Investment Properties [Member]
Disclosure of detailed information about investment property [line items]
Investment properties are depreciated using the straight-line method over their estimated useful lives	20 years

X

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

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- Definition

The useful lives or depreciation rates used for investment property. [Refer: Investment property]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 40
-IssueDate 2017-01-01
-Paragraph 79
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=40&date=2017-03-01&anchor=para_79_b&doctype=Standard
-URIDate 2017-03-09

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