Fair value measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Disposal Group, Held-for-Sale, Not Discontinued Operations | Mahipapa
Financial liabilities
Long-term debt, net	$ 52,000	$ 52,000
Carrying or notional amount
Financial liabilities
Long-term debt, net	2,405,378	2,409,975
Carrying or notional amount | Money market mutual funds
Financial assets
Money market mutual funds	802,999	839,380
Carrying or notional amount | Hawaiian Electric Company, Inc. and Subsidiaries
Financial liabilities
Long-term debt, net	2,183,207	2,182,833
Carrying or notional amount | Hawaiian Electric Company, Inc. and Subsidiaries | Money market mutual funds
Financial assets
Money market mutual funds	308,550	345,510
Estimated fair value
Financial liabilities
Long-term debt, net	2,027,503	2,098,593
Estimated fair value | Money market mutual funds
Financial assets
Money market mutual funds	802,999	839,380
Estimated fair value | Hawaiian Electric Company, Inc. and Subsidiaries
Financial liabilities
Long-term debt, net	1,831,719	1,895,680
Estimated fair value | Hawaiian Electric Company, Inc. and Subsidiaries | Money market mutual funds
Financial assets
Money market mutual funds	308,550	345,510
Estimated fair value | Quoted prices in active markets for identical assets (Level 1)
Financial liabilities
Long-term debt, net	0	0
Estimated fair value | Quoted prices in active markets for identical assets (Level 1) | Money market mutual funds
Financial assets
Money market mutual funds	802,999	839,380
Estimated fair value | Quoted prices in active markets for identical assets (Level 1) | Hawaiian Electric Company, Inc. and Subsidiaries
Financial liabilities
Long-term debt, net	0	0
Estimated fair value | Quoted prices in active markets for identical assets (Level 1) | Hawaiian Electric Company, Inc. and Subsidiaries | Money market mutual funds
Financial assets
Money market mutual funds	308,550	345,510
Estimated fair value | Significant  other observable  inputs (Level 2)
Financial liabilities
Long-term debt, net	2,027,503	2,098,593
Estimated fair value | Significant  other observable  inputs (Level 2) | Money market mutual funds
Financial assets
Money market mutual funds	0	0
Estimated fair value | Significant  other observable  inputs (Level 2) | Hawaiian Electric Company, Inc. and Subsidiaries
Financial liabilities
Long-term debt, net	1,831,719	1,895,680
Estimated fair value | Significant  other observable  inputs (Level 2) | Hawaiian Electric Company, Inc. and Subsidiaries | Money market mutual funds
Financial assets
Money market mutual funds	$ 0	$ 0