Income statement analysis (Tables)

12 Months Ended

Dec. 31, 2018

Analysis of income and expense [abstract]

Summary of finance income and finance costs

					$ million
	2018		2017		2016
Interest and other income
Interest income from
Financial assets measured at amortized cost	421		288		183
Financial assets measured at fair value through profit or loss	39		—		—
Other income	313		369		323
	773		657		506
Currency exchange losses charged to the income statementa	368		83		698
Expenditure on research and development	429		391		400
Finance costs
Interest payable on liabilities measured at amortized cost	2,198		1,718		1,221
Capitalized at 3.56% (2017 2.25% and 2016 1.81%)b	(419	)	(297	)	(244	)
Unwinding of discount on provisions	210		150		310
Unwinding of discount on other payables measured at amortized cost	539		503		388
	2,528		2,074		1,675

^a  Excludes exchange gains and losses arising on financial instruments measured at fair value through profit or loss.

^b  Tax relief on capitalized interest is approximately $55 million (2017$64 million and 2016$56 million).