Retirement benefits Components of NPBC (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension benefits
Defined benefit plans
Service cost	$ 66,260	$ 49,264	$ 56,405
Interest cost	76,960	72,202	64,788
Expected return on plan assets	(88,554)	(81,355)	(72,537)
Amortization of net prior service (gain) cost	4	88	(97)
Amortization of net actuarial loss (gain)	36,800	20,304	38,438
Net periodic pension/benefit cost	91,470	60,503	86,997
Impact of PUC D&Os	(40,011)	(13,324)	(38,104)
Net periodic pension/benefit cost (adjusted for impact of PUC D&Os)	51,459	47,179	48,893
Amounts amortized from AOCI or regulatory assets into net periodic pension benefit cost during 2015
Prior service credit	(100)
Net actuarial loss	23,900
Pension benefits | Hawaiian Electric Company, Inc. and Subsidiaries
Defined benefit plans
Service cost	64,262	47,597	54,482
Interest cost	70,529	65,979	59,119
Expected return on plan assets	(82,541)	(72,661)	(64,551)
Amortization of net prior service (gain) cost	40	62	(464)
Amortization of net actuarial loss (gain)	33,371	18,459	34,597
Net periodic pension/benefit cost	85,661	59,436	83,183
Impact of PUC D&Os	(40,011)	(13,324)	(38,104)
Net periodic pension/benefit cost (adjusted for impact of PUC D&Os)	45,650	46,112	45,079
Amounts amortized from AOCI or regulatory assets into net periodic pension benefit cost during 2015
Prior service credit	0
Net actuarial loss	21,800
Other benefits
Defined benefit plans
Service cost	3,927	3,490	4,306
Interest cost	9,011	8,550	7,569
Expected return on plan assets	(11,664)	(10,902)	(10,147)
Amortization of net prior service (gain) cost	(1,793)	(1,793)	(1,793)
Amortization of net actuarial loss (gain)	1,796	(11)	1,602
Net periodic pension/benefit cost	1,277	(666)	1,537
Impact of PUC D&Os	(240)	1,976	(1,458)
Net periodic pension/benefit cost (adjusted for impact of PUC D&Os)	1,037	1,310	79
Amounts amortized from AOCI or regulatory assets into net periodic pension benefit cost during 2015
Prior service credit	(1,800)
Net actuarial loss	1,100
Other benefits | Hawaiian Electric Company, Inc. and Subsidiaries
Defined benefit plans
Service cost	3,870	3,392	4,163
Interest cost	8,700	8,234	7,288
Expected return on plan assets	(11,495)	(10,739)	(10,002)
Amortization of net prior service (gain) cost	(1,804)	(1,804)	(1,803)
Amortization of net actuarial loss (gain)	1,754	0	1,544
Net periodic pension/benefit cost	1,025	(917)	1,190
Impact of PUC D&Os	(240)	1,976	(1,458)
Net periodic pension/benefit cost (adjusted for impact of PUC D&Os)	785	$ 1,059	$ (268)
Amounts amortized from AOCI or regulatory assets into net periodic pension benefit cost during 2015
Prior service credit	(1,800)
Net actuarial loss	$ 1,100