Loan impairment provisions (Details) - GBP (£) £ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Loan impairment provisions
Financial Assets	£ 799,491	£ 723,039
ECL provisions	£ 6,186	£ 3,792
ECL provision coverage (in percentage)	1.66%	1.13%
ECL charge	£ 3,242	£ 696
ECL loss rate - annualised (basis points)	87.00%	20.00%
Amounts written off	£ 937	£ 792
Contingent liabilities [member]
Loan impairment provisions
ECL charge	28	0
Other financial assets
Loan impairment provisions
Financial Assets	55,148	61,452
ECL charge	12	2
FVOCI
Loan impairment provisions
ECL provisions	6	4
FVOCI \| Other financial assets
Loan impairment provisions
Financial Assets	44,902	49,283
ECL charge	2	1
Loans and advances
Loan impairment provisions
Financial Assets	372,399	336,833
Cash at central banks \| Other financial assets
Loan impairment provisions
Financial Assets	122,800	79,200
Secured \| Other financial assets
Loan impairment provisions
Financial Assets	53,800	59,400
Business loans
Loan impairment provisions
ECL provisions		6,186	£ 3,792
Stage 1
Loan impairment provisions
ECL provisions	£ 519	£ 322
ECL provision coverage (in percentage)	0.18%	0.11%
ECL charge	£ (121)	£ (212)
Stage 1 \| Loans and advances
Loan impairment provisions
Financial Assets	287,124	302,367
Stage 2
Loan impairment provisions
ECL provisions	£ 3,081	£ 752
ECL provision coverage (in percentage)	3.90%	2.70%
ECL charge	£ 2,747	£ 318
Stage 2 \| Loans and advances
Loan impairment provisions
Financial Assets	78,917	27,868
Stage 3
Loan impairment provisions
ECL provisions	£ 2,586	£ 2,718
ECL provision coverage (in percentage)	40.67%	41.19%
ECL charge	£ 616	£ 590
Stage 3 \| Loans and advances
Loan impairment provisions
Financial Assets	6,358	6,598
Of which: individual
Loan impairment provisions
ECL provisions	831	796
ECL charge	194	303
Amounts written off	191	372
Of which: individual \| Loans and advances
Loan impairment provisions
Financial Assets	2,292	2,051
Of which: collective
Loan impairment provisions
ECL provisions	1,755	1,922
ECL charge	422	287
Amounts written off	746	420
Of which: collective \| Loans and advances
Loan impairment provisions
Financial Assets	£ 4,066	£ 4,547

The decrease in financial assets resulting from write-off. [Refer: Financial assets]

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The rate of expected credit losses, calculated as percentage of the gross carrying amount. Expected credit losses are the weighted average of credit losses with the respective risks of a default occurring as the weights.

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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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- Definition

The amount of loan impairment provision for expected credit losses.

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The rate of provision coverage for expected credit losses.

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