Fair value measurement - Summary of Carrying Amounts and Fair Values of Financial Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Financial assets
Cash and cash equivalents	$ 168	$ 206
Equity securities available-for-sale	127	156
Loans and receivables:
Other financial assets	117	112
Trade and other receivables, excluding prepayments	477	403
Financial assets	889	877
Financial liabilities
Loans and other borrowings	(2,019)	(1,712)
Loyalty programme liability	(760)	(685)
Trade and other payables	(889)	(881)
Derivatives		(3)
Provisions	(8)	(8)
Financial Liabilities	(3,676)	(3,289)
GBP400m 3.875% bonds 2022 [member]
Financial liabilities
Loans and other borrowings	(538)	(489)
GBP300m 3.75% bonds 2025 [member]
Financial liabilities
Loans and other borrowings	(406)	(370)
GBP350m 2.125% bonds 2026 [member]
Financial liabilities
Loans and other borrowings	(472)	(430)
Finance lease obligations [member]
Financial liabilities
Loans and other borrowings	(231)	(227)
Unsecured bank loans [member]
Financial liabilities
Loans and other borrowings	(262)	(107)
Bank overdrafts [member]
Financial liabilities
Loans and other borrowings	(110)	(89)
Fair value [member]
Financial assets
Cash and cash equivalents	168	206
Equity securities available-for-sale	127	156
Loans and receivables:
Other financial assets	117	112
Trade and other receivables, excluding prepayments	477	403
Financial assets	889	877
Financial liabilities
Loyalty programme liability	(760)	(685)
Trade and other payables	(889)	(881)
Derivatives		(3)
Provisions	(8)	(8)
Financial Liabilities	(3,835)	(3,430)
Fair value [member] \| GBP400m 3.875% bonds 2022 [member]
Financial liabilities
Loans and other borrowings	(593)	(541)
Fair value [member] \| GBP300m 3.75% bonds 2025 [member]
Financial liabilities
Loans and other borrowings	(441)	(408)
Fair value [member] \| GBP350m 2.125% bonds 2026 [member]
Financial liabilities
Loans and other borrowings	(454)	(411)
Fair value [member] \| Finance lease obligations [member]
Financial liabilities
Loans and other borrowings	(318)	(297)
Fair value [member] \| Unsecured bank loans [member]
Financial liabilities
Loans and other borrowings	(262)	(107)
Fair value [member] \| Bank overdrafts [member]
Financial liabilities
Loans and other borrowings	$ (110)	$ (89)

The amount of outstanding funds that the entity is obligated to repay.

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The amount of cash on hand and demand deposits, along with short-term, highly liquid investments that are readily convertible to known amounts of cash and that are subject to an insignificant risk of changes in value. [Refer: Cash; Cash equivalents]

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The amount of assets that are: (a) cash; (b) an equity instrument of another entity; (c) a contractual right: (i) to receive cash or another financial asset from another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially favourable to the entity; or (d) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to receive a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose the entity’s own equity instruments do not include puttable financial instruments classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. [Refer: Financial instruments, class [member]; Financial liabilities]

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The amount of non-derivative financial assets that are designated as available for sale or are not classified as (a) loans and receivables; (b) held-to-maturity investments; or (c) financial assets at fair value through profit or loss. [Refer: Derivative financial assets; Financial assets at fair value through profit or loss; Held-to-maturity investments]

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The amount of trade payables and other payables. [Refer: Trade payables; Other payables]

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