Report Of The Directors Financial Review Risk Report - Market risk (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Market risk
Disclosure of nature and extent of risks arising from financial instruments [line items]
Cost of guarantees	$ 669	$ 696

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

No definition available.

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