Statement Of Changes In Equity [Abstract]

United Utilities Group PLC - Filing #6816965

Concept	As at 2025-03-31	As at 2025-03-31	2024-04-01 to 2025-03-31	As at 2025-03-31	2024-04-01 to 2025-03-31	As at 2025-03-31	As at 2025-03-31	2024-04-01 to 2025-03-31	2024-04-01 to 2025-03-31	2024-04-01 to 2025-03-31	2023-04-01 to 2024-03-31	As at 2024-03-31	As at 2024-03-31	As at 2024-03-31	As at 2024-03-31	2023-04-01 to 2024-03-31	As at 2024-03-31	2023-04-01 to 2024-03-31	2023-04-01 to 2024-03-31	2023-04-01 to 2024-03-31	As at 2023-03-31	As at 2023-03-31	As at 2023-03-31	As at 2023-03-31	As at 2023-03-31
Statement of changes in equity [abstract]
Statement of changes in equity [line items]
Equity	319,200,000 GBP	1,999,900,000 GBP	—	2,900,000 GBP	—	499,800,000 GBP	1,178,000,000 GBP	—	—	—	—	311,100,000 GBP	1,242,300,000 GBP	2,900,000 GBP	499,800,000 GBP	—	2,056,100,000 GBP	—	—	—	2,508,700,000 GBP	2,900,000 GBP	499,800,000 GBP	1,652,600,000 GBP	353,400,000 GBP
Changes in equity [abstract]
Comprehensive income [abstract]
Profit (loss)	—	—	264,700,000 GBP	—	264,700,000 GBP	—	—	– GBP	– GBP	– GBP	– GBP	—	—	—	—	126,900,000 GBP	—	– GBP	– GBP	126,900,000 GBP	—	—	—	—	—
Comprehensive income	—	—	288,200,000 GBP	—	280,100,000 GBP	—	—	– GBP	– GBP	8,100,000 GBP	42,300,000 GBP	—	—	—	—	130,900,000 GBP	—	– GBP	– GBP	88,600,000 GBP	—	—	—	—	—
Dividends recognised as distributions to owners	—	—	344,100,000 GBP	—	344,100,000 GBP	—	—	– GBP	– GBP	– GBP	– GBP	—	—	—	—	320,000,000 GBP	—	– GBP	– GBP	320,000,000 GBP	—	—	—	—	—
Increase (decrease) through share-based payment transactions, equity	—	—	4,700,000 GBP	—	4,700,000 GBP	—	—	– GBP	– GBP	– GBP	– GBP	—	—	—	—	2,100,000 GBP	—	– GBP	– GBP	2,100,000 GBP	—	—	—	—	—