Intangible assets (Tables)

12 Months Ended

Dec. 31, 2019

Intangible Assets [Abstract]

Disclosure of detailed information about intangible assets

The carrying amount, by location, of exploration and appraisal expenditure capitalized as intangible assets at 31 December 2019 is shown in the table below.

Carrying amount	Location
$1 - 2 billion	Angola; Egypt; Middle East
$2 - 3 billion	US - Gulf of Mexico; Canada; Brazil

											$ million
					2019						2018
	Exploration and appraisal expenditurea		Other intangibles		Total		Exploration and appraisal expenditurea		Other intangibles		Total
Cost
At 1 January	17,053		4,504		21,557		17,886		4,488		22,374
Exchange adjustments	—		2		2		—		(128	)	(128	)
Acquisitions	—		35		35		—		25		25
Additions	1,268		457		1,725		1,095		318		1,413
Transfers to property, plant and equipment	(1,885	)	—		(1,885	)	(901	)	—		(901	)
Reclassified as assets held for sale	(671	)	—		(671	)	—		—		—
Deletions	(459	)	(98	)	(557	)	(1,027	)	(199	)	(1,226	)
At 31 December	15,306		4,900		20,206		17,053		4,504		21,557
Amortization
At 1 January	1,064		3,209		4,273		860		3,159		4,019
Exchange adjustments	—		4		4		—		(77	)	(77	)
Charge for the year	631		331		962		1,085		326		1,411
Impairment losses	2		2		4		137		—		137
Reclassified as assets held for sale	(61	)	—		(61	)	—		—		—
Deletions	(421	)	(94	)	(515	)	(1,018	)	(199	)	(1,217	)
At 31 December	1,215		3,452		4,667		1,064		3,209		4,273
Net book amount at 31 December	14,091		1,448		15,539		15,989		1,295		17,284
Net book amount at 1 January	15,989		1,295		17,284		17,026		1,329		18,355

^a For further information see Intangible assets within Note 1 and Note 8.