v3.19.1
Associates and Joint Ventures - Summary of Group's Share of the Result of Associates and Joint Ventures (Details) - GBP (£)
£ in Millions
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Disclosure Of Analysis Of Other Comprehensive Income By Item [Line Items]      
Profit on ordinary activities after taxation attributable to owners of the Parent £ 6,032   £ 4,648
Other comprehensive income:      
Total comprehensive income for the year, net of tax 9,424   6,426
Groups Share in Associates and Joint Ventures      
Disclosure Of Analysis Of Other Comprehensive Income By Item [Line Items]      
Profit on ordinary activities after taxation attributable to owners of the Parent 419 £ 24,209 2,227
Other comprehensive income:      
Items that may be reclassified to profit & loss (38) (918) 1,415
Items that will not be reclassified to profit & loss 6 25 20
Groups Share in Associates and Joint Ventures | Investments Accounted for Using Equity Method      
Other comprehensive income:      
Total comprehensive income for the year, net of tax £ 387 £ 23,316 £ 3,662