Retirement benefits (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Defined benefit plans
Expected payments for remainder of fiscal year	$ 2,000,000		$ 2,000,000
Payments for benefits					$ 1,000,000
Retirement benefits expense			$ 18,000,000	$ 18,000,000
Number of years for which regulatory asset/liability for each utility will be amortized, beginning with respective utility's next rate case			5 years
Defined contribution plan, expenses recognized			$ 2,800,000	2,700,000
Cash contributions by the employer to defined contribution plan			3,700,000	3,400,000
Pension benefits
Defined benefit plans
Contributions made to defined benefit plans			33,000,000	44,000,000
Contributions expected to be paid in current year			65,000,000		88,000,000
Service cost	14,913,000	$ 16,640,000	30,304,000	33,106,000
Interest cost	20,481,000	19,363,000	40,758,000	38,502,000
Expected return on plan assets	(24,616,000)	(22,149,000)	(49,280,000)	(44,300,000)
Amortization of net prior service loss (gain)	(14,000)	1,000	(28,000)	2,000
Amortization of net actuarial loss	6,408,000	9,455,000	12,377,000	18,417,000
Net periodic benefit cost	17,172,000	23,310,000	34,131,000	45,727,000
Impact of PUC D&Os	(4,765,000)	(10,464,000)	(8,811,000)	(19,977,000)
Net periodic benefit cost (adjusted for impact of PUC D&Os)	12,407,000	12,846,000	25,320,000	25,750,000
Pension benefits | American Savings Bank (ASB)
Defined benefit plans
Contributions expected to be paid in current year			0		0
Other benefits
Defined benefit plans
Service cost	832,000	1,094,000	1,668,000	1,963,000
Interest cost	2,363,000	2,268,000	4,837,000	4,503,000
Expected return on plan assets	(3,091,000)	(2,934,000)	(6,143,000)	(5,841,000)
Amortization of net prior service loss (gain)	(448,000)	(449,000)	(896,000)	(897,000)
Amortization of net actuarial loss	116,000	466,000	403,000	896,000
Net periodic benefit cost	(228,000)	445,000	(131,000)	624,000
Impact of PUC D&Os	483,000	(218,000)	672,000	(120,000)
Net periodic benefit cost (adjusted for impact of PUC D&Os)	255,000	227,000	541,000	504,000
Hawaiian Electric Company, Inc. and Subsidiaries
Defined benefit plans
Expected payments for remainder of fiscal year	1,000,000		1,000,000
Payments for benefits					400,000
Retirement benefits expense			16,000,000	15,000,000
Defined contribution plan, expenses recognized			800,000	700,000
Cash contributions by the employer to defined contribution plan			800,000	700,000
Hawaiian Electric Company, Inc. and Subsidiaries | Pension benefits
Defined benefit plans
Contributions made to defined benefit plans			32,000,000	43,000,000
Contributions expected to be paid in current year			64,000,000		86,000,000
Service cost	14,465,000	16,148,000	29,398,000	32,131,000
Interest cost	18,801,000	17,749,000	37,404,000	35,265,000
Expected return on plan assets	(22,885,000)	(20,639,000)	(45,817,000)	(41,271,000)
Amortization of net prior service loss (gain)	3,000	10,000	7,000	20,000
Amortization of net actuarial loss	5,885,000	8,592,000	11,346,000	16,686,000
Net periodic benefit cost	16,269,000	21,860,000	32,338,000	42,831,000
Impact of PUC D&Os	(4,765,000)	(10,464,000)	(8,811,000)	(19,977,000)
Net periodic benefit cost (adjusted for impact of PUC D&Os)	11,504,000	11,396,000	23,527,000	22,854,000
Hawaiian Electric Company, Inc. and Subsidiaries | Other benefits
Defined benefit plans
Service cost	820,000	1,080,000	1,642,000	1,935,000
Interest cost	2,280,000	2,191,000	4,669,000	4,350,000
Expected return on plan assets	(3,046,000)	(2,889,000)	(6,049,000)	(5,748,000)
Amortization of net prior service loss (gain)	(451,000)	(451,000)	(902,000)	(902,000)
Amortization of net actuarial loss	113,000	455,000	397,000	877,000
Net periodic benefit cost	(284,000)	386,000	(243,000)	512,000
Impact of PUC D&Os	483,000	(218,000)	672,000	(120,000)
Net periodic benefit cost (adjusted for impact of PUC D&Os)	$ 199,000	$ 168,000	429,000	$ 392,000
Hawaiian Electric Industries, Inc. | Pension benefits
Defined benefit plans
Contributions expected to be paid in current year			$ 1,000,000		$ 2,000,000