Valuation and qualifying accounts (Notes)

12 Months Ended

Dec. 31, 2017

Valuation and Qualifying Accounts [Abstract]

Valuation and qualifying accounts

Valuation and qualifying accounts

											$ million
			2017				2016				2015
	Accounts receivable		Fixed asset investments		Accounts receivable		Fixed asset investments		Accounts receivable		Fixed asset investments
At 1 January	392		335		447		435		331		517
Charged to costs and expenses	68		47		120		55		243		195
Charged to other accountsa	13		3		(7	)	(2	)	(23	)	(4	)
Deductions	(138	)	(71	)	(168	)	(153	)	(104	)	(273	)
At 31 December	335		314		392		335		447		435

^a  Principally exchange adjustments.

Valuation and qualifying accounts comprise impairment provisions for accounts receivable and fixed asset investments, and are deducted in the balance sheet from the assets to which they apply.

For information on significant judgements made in relation to the recoverability of trade receivables see Impairment of loans and receivables within Note 1.