Retirement benefits Components of NPBC (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension benefits
Defined benefit plans
Service cost	$ 49,264	$ 56,405	$ 43,221
Interest cost	72,202	64,788	67,480
Expected return on plan assets	(81,355)	(72,537)	(71,183)
Amortization of net transition obligation	0	0	1
Amortization of net prior service (gain) cost	88	(97)	(325)
Amortization of net actuarial loss (gain)	20,304	38,438	25,675
Net periodic benefit cost	60,503	86,997	64,869
Impact of PUC D&Os	(13,324)	(38,104)	(15,754)
Net periodic benefit cost (adjusted for impact of PUC D&Os)	47,179	48,893	49,115
Amounts amortized from AOCI or regulatory assets into net periodic pension benefit cost during 2015
Prior service credit	0
Net actuarial loss	35,800
Net transition obligation	0
Pension benefits | Hawaiian Electric Company, Inc. and Subsidiaries
Defined benefit plans
Service cost	47,597	54,482	41,603
Interest cost	65,979	59,119	61,453
Expected return on plan assets	(72,661)	(64,551)	(64,004)
Amortization of net prior service (gain) cost	62	(464)	(689)
Amortization of net actuarial loss (gain)	18,459	34,597	23,428
Net periodic benefit cost	59,436	83,183	61,791
Impact of PUC D&Os	(13,324)	(38,104)	(15,754)
Net periodic benefit cost (adjusted for impact of PUC D&Os)	46,112	45,079	46,037
Amounts amortized from AOCI or regulatory assets into net periodic pension benefit cost during 2015
Prior service credit	0
Net actuarial loss	32,400
Net transition obligation	0
Other benefits
Defined benefit plans
Service cost	3,490	4,306	4,211
Interest cost	8,550	7,569	9,009
Expected return on plan assets	(10,902)	(10,147)	(10,336)
Amortization of net prior service (gain) cost	(1,793)	(1,793)	(1,793)
Amortization of net actuarial loss (gain)	(11)	1,602	1,498
Net periodic benefit cost	(666)	1,537	2,589
Impact of PUC D&Os	1,976	(1,458)	(2,227)
Net periodic benefit cost (adjusted for impact of PUC D&Os)	1,310	79	362
Amounts amortized from AOCI or regulatory assets into net periodic pension benefit cost during 2015
Prior service credit	(1,800)
Net actuarial loss	1,700
Net transition obligation	0
Other benefits | Hawaiian Electric Company, Inc. and Subsidiaries
Defined benefit plans
Service cost	3,392	4,163	4,014
Interest cost	8,234	7,288	8,703
Expected return on plan assets	(10,739)	(10,002)	(10,195)
Amortization of net transition obligation	0	0	(9)
Amortization of net prior service (gain) cost	(1,804)	(1,803)	(1,803)
Amortization of net actuarial loss (gain)	0	1,544	1,455
Net periodic benefit cost	(917)	1,190	2,165
Impact of PUC D&Os	1,976	(1,458)	(2,227)
Net periodic benefit cost (adjusted for impact of PUC D&Os)	1,059	$ (268)	$ (62)
Amounts amortized from AOCI or regulatory assets into net periodic pension benefit cost during 2015
Prior service credit	(1,800)
Net actuarial loss	1,700
Net transition obligation	$ 0