Statement Of Changes In Equity [Abstract]

HEADLAM GROUP PLC - Filing #1587521

Concept	As at 2021-12-31	As at 2021-12-31	As at 2021-12-31	2021-01-01 to 2021-12-31	As at 2021-12-31	2021-01-01 to 2021-12-31	As at 2021-12-31	2021-01-01 to 2021-12-31	2021-01-01 to 2021-12-31	2021-01-01 to 2021-12-31	As at 2021-12-31	2021-01-01 to 2021-12-31	As at 2021-12-31	As at 2021-12-31	2021-01-01 to 2021-12-31	2021-01-01 to 2021-12-31	2020-01-01 to 2020-12-31	As at 2020-12-31	As at 2020-12-31	2020-01-01 to 2020-12-31	2020-01-01 to 2020-12-31	As at 2020-12-31	2020-01-01 to 2020-12-31	As at 2020-12-31	As at 2020-12-31	As at 2020-12-31	2020-01-01 to 2020-12-31	As at 2020-12-31	2020-01-01 to 2020-12-31	2020-01-01 to 2020-12-31	As at 2020-12-31	2020-01-01 to 2020-12-31	As at 2019-12-31	As at 2019-12-31	As at 2019-12-31	As at 2019-12-31	As at 2019-12-31	As at 2019-12-31	As at 2019-12-31	As at 2019-12-31
Statement of changes in equity [abstract]
Statement of changes in equity [line items]
Equity	4,900,000 GBP	175,900,000 GBP	100,000 GBP	—	1,500,000 GBP	—	232,100,000 GBP	—	—	—	53,500,000 GBP	—	1,700,000 GBP	4,300,000 GBP	—	—	—	158,800,000 GBP	1,500,000 GBP	—	—	4,300,000 GBP	—	5,900,000 GBP	7,700,000 GBP	53,500,000 GBP	—	220,000,000 GBP	—	—	100,000 GBP	—	6,800,000 GBP	245,100,000 GBP	53,500,000 GBP	500,000 GBP	186,000,000 GBP	6,100,000 GBP	100,000 GBP	4,300,000 GBP
Changes in equity [abstract]
Comprehensive income [abstract]
Other comprehensive income	—	—	—	– GBP	—	– GBP	—	– GBP	– GBP	6,000,000 GBP	—	– GBP	—	—	7,800,000 GBP	1,800,000 GBP	700,000 GBP	—	—	– GBP	– GBP	—	200,000 GBP	—	—	—	– GBP	—	900,000 GBP	– GBP	—	– GBP	—	—	—	—	—	—	—	—
Comprehensive income	—	—	—	– GBP	—	– GBP	—	– GBP	– GBP	6,000,000 GBP	—	– GBP	—	—	16,600,000 GBP	22,600,000 GBP	19,600,000 GBP	—	—	– GBP	– GBP	—	20,500,000 GBP	—	—	—	– GBP	—	900,000 GBP	– GBP	—	– GBP	—	—	—	—	—	—	—	—
Issue of equity	—	—	—	—	—	—	—	—	—	—	—	—	—	—	—	—	1,000,000 GBP	—	—	1,000,000 GBP	– GBP	—	– GBP	—	—	—	– GBP	—	– GBP	– GBP	—	– GBP	—	—	—	—	—	—	—	—
Dividends recognised as distributions to owners	—	—	—	– GBP	—	– GBP	—	– GBP	– GBP	– GBP	—	– GBP	—	—	6,600,000 GBP	6,600,000 GBP	6,300,000 GBP	—	—	– GBP	– GBP	—	6,300,000 GBP	—	—	—	– GBP	—	– GBP	– GBP	—	– GBP	—	—	—	—	—	—	—	—
Increase (decrease) through share-based payment transactions, equity	—	—	—	– GBP	—	– GBP	—	– GBP	– GBP	– GBP	—	– GBP	—	—	1,200,000 GBP	1,200,000 GBP	100,000 GBP	—	—	– GBP	– GBP	—	100,000 GBP	—	—	—	– GBP	—	– GBP	– GBP	—	– GBP	—	—	—	—	—	—	—	—