XML 98 R66.htm IDEA: XBRL DOCUMENT v3.19.2
Ordinary dividends - Additional Information (Detail) - £ / shares
 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Interim period amount [member]    
Disclosure of Dividends [line items]    
Amounts recognised as distributions to equity holders, per share £ 22.7 £ 22.7
Dividends payable date Nov. 04, 2019  
Previous period final amount [member]    
Disclosure of Dividends [line items]    
Amounts recognised as distributions to equity holders, per share £ 37.3  
Dividends paid date Jul. 08, 2019