Consolidated Statements of Comprehensive Income - HECO - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net income for common stock	$ 50,485	$ 65,032	$ 48,887	$ 33,420	$ 66,263	$ 63,419	$ 42,512	$ 45,688	$ 197,824	$ 217,882	$ 201,774
Retirement benefit plans:
Net gains (losses) arising during the period, net of taxes of $(21,868), $1,821 and $(9,024) for 2020, 2019 and 2018, respectively									(60,529)	10,914	(28,101)
Adjustment for amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of taxes of $7,474, $3,312 and $6,594 for 2020, 2019 and 2018, respectively									23,689	10,107	21,015
Reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $13,825, $(5,610), and $2,887 for 2020, 2019 and 2018, respectively									39,860	(16,177)	8,325
Other comprehensive income (loss), net of taxes									18,775	30,571	(8,669)
Comprehensive income									216,599	248,453	193,105
Hawaiian Electric Company, Inc. and Subsidiaries
Net income for common stock	$ 43,041	$ 60,065	$ 42,329	$ 23,905	$ 45,361	$ 46,779	$ 32,574	$ 32,126	169,340	156,840	143,653
Retirement benefit plans:
Net gains (losses) arising during the period, net of taxes of $(21,868), $1,821 and $(9,024) for 2020, 2019 and 2018, respectively									(63,050)	5,249	(26,019)
Adjustment for amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of taxes of $7,474, $3,312 and $6,594 for 2020, 2019 and 2018, respectively									21,550	9,550	19,012
Reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $13,825, $(5,610), and $2,887 for 2020, 2019 and 2018, respectively									39,860	(16,177)	8,325
Other comprehensive income (loss), net of taxes									(1,640)	(1,378)	1,318
Comprehensive income									$ 167,700	$ 155,462	$ 144,971