Contingent liabilities and financial commitments - Other contingencies - Additional Information (Details) - ProductLiabilityAction	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Competition investigations
Disclosure Of Commitments And Contingencies [Line Items]
Monitorship period		2 years
Loews
Disclosure Of Commitments And Contingencies [Line Items]
Loss contingency number of indemnity cases pending	3

Loss contingency number of indemnity cases pending.

No definition available.

Name:	bti_LossContingencyNumberOfIndemnityCasesPending
Namespace Prefix:	bti_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration