Shareholders' equity - Reclassification out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Reclassifications out of accumulated other comprehensive income/(loss)
Revenues	$ (608,945)	$ (715,485)	$ (1,286,131)	$ (1,377,100)
Total reclassifications	(1,107)	205	(559)	410
Bank
Reclassifications out of accumulated other comprehensive income/(loss)
Revenues	(74,714)	(81,687)	(154,452)	(164,739)
Hawaiian Electric Company, Inc. and Subsidiaries
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	25	23	51	47
Net realized gains on securities included in net income | Reclassification out of Accumulated Other Comprehensive Income | Bank
Reclassifications out of accumulated other comprehensive income/(loss)
Revenues	(1,638)	0	(1,638)	0
Amortization of prior service credit and net losses recognized during the period in net periodic benefit cost
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	5,690	2,503	11,396	5,006
Amortization of prior service credit and net losses recognized during the period in net periodic benefit cost | Hawaiian Electric Company, Inc. and Subsidiaries
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	5,184	2,321	10,368	4,643
Impact of D&Os of the PUC included in regulatory assets
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	(5,159)	(2,298)	(10,317)	(4,596)
Impact of D&Os of the PUC included in regulatory assets | Hawaiian Electric Company, Inc. and Subsidiaries
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	$ (5,159)	$ (2,298)	$ (10,317)	$ (4,596)