Other intangible assets Current assets Other intangible assets Current assets Payments relating to exceptional charges in operating costs Payments relating to exceptional charges in operating costs Repayments of borrowings, classified as financing activities Disclosure of Merger, capital redemption and other reserves [Text Block] Disclosure of Merger, capital redemption and other reserves Description of Accounting policy for Overlift and Underlift [Text Block] Description of Accounting policy for Overlift and Underlift Dividends paid to equity holders of parent, classified as financing activities Group revenue Group revenue Insurance contracts that are liabilities Unrealised (gains)/losses arising from re-measurement of energy contracts Unrealised (gains)/losses arising from re-measurement of energy contracts Re-measurement and settlement of derivative energy contracts Re-measurement and settlement of derivative energy contracts Credit losses on financial assets Credit losses on financial assets Insurance services operating costs Insurance services operating costs Non current Securities Non current Securities Share buyback programme Share buyback programme Cash flows used in obtaining control of subsidiaries or other businesses, classified as investing activities Accounting policy for Cloud Computing arrangements [Text Block] Accounting policy for Cloud Computing arrangements Operating cash flows before payments relating to taxes, exceptional charges and operating interest Operating cash flows before payments relating to taxes, exceptional charges and operating interest Trade and other non-current payables Exchange Differences On Translation Of Foreign Operations Attributable To Non Controlling Interests Exchange Differences On Translation Of Foreign Operations Attributable To Non Controlling Interests Exchange Differences On Translation Of Foreign Operations Attributable To Non Controlling Interests Non-current portion of non-current borrowings Operating expense Investments in joint ventures and associates classified as investing activities Investments in joint ventures and associates classified as investing activities Business Performance [Member] Business Performance climate change [Text Block] climate change Non-current net defined benefit liability Purchase of interests in investments accounted for using equity method Interim dividend paid per ordinary share Interim dividend paid per ordinary share Group Income Statement [Axis] Group Income Statement Share buyback programme classified as financing activities Share buyback programme classified as financing activities Share buyback programme classified as financing activities Exceptional items Exceptional items Sources of Finance [Text Block] Sources of Finance Share of profit (loss) of associates and joint ventures accounted for using equity method Accounting policy for re-measurement and settlement of energy contracts [Text Block] Accounting policy for re-measurement and settlement of energy contracts Interest paid, classified as financing activities Accounting Policy for Renewable certificates [Text Block] Accounting Policy for Renewable certificates Current borrowings and current portion of non-current borrowings Disclosure of Exceptional Items and Certain Re-measurements [Text Block] Disclosure of Exceptional Items and Certain Re-measurements Deferred tax liabilities Current derivative financial liabilities Current Securities Current Securities Dividends paid to non-controlling interests, classified as financing activities Description of accounting policy for use of adjusted performance measures [Text Block] Description of accounting policy for use of adjusted performance measures Results for the year [Member] Results for the year Non-current liabilities Insurance services cost of sales Insurance services cost of sales Purchase of property, plant and equipment, classified as investing activities Non-current provisions Trade and other current payables Description Of Accounting Policy For Exceptional Items And Certain Re-Measurements [Text Block] Description Of Accounting Policy For Exceptional Items And Certain Re-Measurements Description of accounting policy for Nuclear activity [Text Block] Description of accounting policy for Nuclear activity Adjustments for (gain)/loss on disposals Adjustments for (gain)/loss on disposals Current tax liabilities Group operating profit before share of results of joint ventures and associates Group operating profit before share of results of joint ventures and associates Group Income Statement [Member] Group Income Statement Accounting Policy for UK and EU emissions trading scheme [Text Block] Accounting Policy for UK and EU emissions trading scheme Description of Accounting policy for Securities [Text Block] Description of Accounting policy for Securities Accounting policy for cost of sales [Text Block] Accounting policy for cost of sales Operating costs before insurance services operating costs, exceptional items and credit losses on financial assets Operating costs before insurance services operating costs, exceptional items and credit losses on financial assets cost of sales Onerous energy supply contract provision cost of sales Onerous contract provision cost of sales Onerous contract provision Other cash payments to acquire equity or debt instruments of other entities, classified as investing activities Exchange Differences On Translation Of Foreign Operations Attributable To Equity Holders Of Parent Exchange Differences On Translation Of Foreign Operations Attributable To Equity Holders Of Parent Non-current derivative financial liabilities Exceptional items and certain re-measurements [Member] Exceptional items and certain re-measurements Current provisions Description of accounting policy for Other investments [Text Block] Description of accounting policy for Other investments