Retirement benefits (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Defined benefit plans
Expected payments for remainder of fiscal year	$ 2,000,000
Payments for benefits			$ 2,000,000
Retirement benefits expense	$ 9,000,000	$ 9,000,000
Number of years for which regulatory asset/liability for each utility will be amortized, beginning with respective utility's next rate case (in years)	5 years
Defined contribution plan, expenses recognized	$ 1,500,000	1,400,000
Cash contributions by the employer to defined contribution plan	2,900,000	2,700,000
Pension benefits
Defined benefit plans
Contributions made to defined benefit plans	17,000,000	16,000,000
Contributions expected to be paid in current year	67,000,000		65,000,000
Service cost	16,494,000	15,391,000
Interest cost	20,216,000	20,277,000
Expected return on plan assets	(25,721,000)	(24,664,000)
Amortization of net prior service loss (gain)	(14,000)	(14,000)
Amortization of net actuarial loss	6,513,000	5,969,000
Net periodic benefit cost	17,488,000	16,959,000
Impact of PUC D&Os	(5,156,000)	(4,046,000)
Net periodic benefit cost (adjusted for impact of PUC D&Os)	12,332,000	12,913,000
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	840,000	836,000
Interest cost	2,411,000	2,474,000
Expected return on plan assets	(3,066,000)	(3,052,000)
Amortization of net prior service loss (gain)	(449,000)	(448,000)
Amortization of net actuarial loss	366,000	287,000
Net periodic benefit cost	102,000	97,000
Impact of PUC D&Os	146,000	189,000
Net periodic benefit cost (adjusted for impact of PUC D&Os)	248,000	286,000
Hawaiian Electric Company, Inc. and Subsidiaries
Defined benefit plans
Expected payments for remainder of fiscal year	1,000,000
Payments for benefits			1,000,000
Retirement benefits expense	8,000,000	8,000,000
Defined contribution plan, expenses recognized	500,000	400,000
Cash contributions by the employer to defined contribution plan	500,000	400,000
Hawaiian Electric Company, Inc. and Subsidiaries | Pension benefits
Defined benefit plans
Contributions made to defined benefit plans	17,000,000	16,000,000
Contributions expected to be paid in current year	66,000,000		64,000,000
Service cost	16,094,000	14,933,000
Interest cost	18,589,000	18,603,000
Expected return on plan assets	(24,011,000)	(22,932,000)
Amortization of net prior service loss (gain)	2,000	4,000
Amortization of net actuarial loss	6,006,000	5,461,000
Net periodic benefit cost	16,680,000	16,069,000
Impact of PUC D&Os	(5,156,000)	(4,046,000)
Net periodic benefit cost (adjusted for impact of PUC D&Os)	11,524,000	12,023,000
Hawaiian Electric Company, Inc. and Subsidiaries | Other benefits
Defined benefit plans
Service cost	835,000	822,000
Interest cost	2,327,000	2,389,000
Expected return on plan assets	(3,017,000)	(3,003,000)
Amortization of net prior service loss (gain)	(451,000)	(451,000)
Amortization of net actuarial loss	359,000	284,000
Net periodic benefit cost	53,000	41,000
Impact of PUC D&Os	146,000	189,000
Net periodic benefit cost (adjusted for impact of PUC D&Os)	199,000	$ 230,000
Hawaiian Electric Industries, Inc. | Pension benefits
Defined benefit plans
Contributions expected to be paid in current year	$ 1,000,000		$ 1,000,000