Inventories and Supplies - Summary of Cost of Inventories and Supplies Recognized as Expense (Detail) - PHP (₱) ₱ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Classes Of Inventories [Abstract]
Cost of sales	₱ 9,528	₱ 10,630	₱ 10,945
Repairs and maintenance	823	688	716
Provisions (Note 5)	471	1,528	907
Selling and promotions	138	43	1
Inventories and supplies recognized as expense	₱ 10,960	₱ 12,889	₱ 12,569

The amount of expense recognised related to the write-down of inventories to net realisable value. [Refer: Inventories]

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