Construction in Progress - Summary of Construction in Progress (Detail) - CNY (¥) ¥ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Disclosure of detailed information about property, plant and equipment [abstract]
Beginning balance	¥ 67,978	¥ 72,180
Additions	176,422	163,312
Transferred to property, plant and equipment	(172,749)	(167,514)
Ending balance	¥ 71,651	¥ 67,978

The increase (decrease) in property, plant and equipment resulting from transfers from construction in progress. [Refer: Property, plant and equipment; Construction in progress]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 16
-IssueDate 2020-01-01
-Paragraph 73
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=16&code=ifrs-tx-2020-en-r&anchor=para_73_e&doctype=Standard
-URIDate 2020-01-01

Name:	ifrs-full_IncreaseDecreaseThroughTransfersFromConstructionInProgressPropertyPlantAndEquipment
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration