Retirement benefits Components of NPBC (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension benefits
Defined benefit plans
Service cost	$ 49,264,000	$ 56,405,000	$ 43,221,000
Interest cost	72,202,000	64,788,000	67,480,000
Expected return on plan assets	(81,355,000)	(72,537,000)	(71,183,000)
Amortization of net transition obligation	0	0	1,000
Amortization of net prior service (gain) cost	88,000	(97,000)	(325,000)
Amortization of net actuarial loss (gain)	20,304,000	38,438,000	25,675,000
Net periodic benefit cost	60,503,000	86,997,000	64,869,000
Impact of PUC D&Os	(13,324,000)	(38,104,000)	(15,754,000)
Net periodic benefit cost (adjusted for impact of PUC D&Os)	47,179,000	48,893,000	49,115,000
Amounts amortized from AOCI or regulatory assets into net periodic pension benefit cost during 2015
Prior service credit	0
Net actuarial loss	35,800,000
Net transition obligation	0
Pension benefits | Hawaiian Electric Company, Inc. and Subsidiaries
Defined benefit plans
Service cost	47,597,000	54,482,000	41,603,000
Interest cost	65,979,000	59,119,000	61,453,000
Expected return on plan assets	(72,661,000)	(64,551,000)	(64,004,000)
Amortization of net prior service (gain) cost	62,000	(464,000)	(689,000)
Amortization of net actuarial loss (gain)	18,459,000	34,597,000	23,428,000
Net periodic benefit cost	59,436,000	83,183,000	61,791,000
Impact of PUC D&Os	(13,324,000)	(38,104,000)	(15,754,000)
Net periodic benefit cost (adjusted for impact of PUC D&Os)	46,112,000	45,079,000	46,037,000
Amounts amortized from AOCI or regulatory assets into net periodic pension benefit cost during 2015
Prior service credit	0
Net actuarial loss	32,400,000
Net transition obligation	0
Other benefits
Defined benefit plans
Service cost	3,490,000	4,306,000	4,211,000
Interest cost	8,550,000	7,569,000	9,009,000
Expected return on plan assets	(10,902,000)	(10,147,000)	(10,336,000)
Amortization of net prior service (gain) cost	(1,793,000)	(1,793,000)	(1,793,000)
Amortization of net actuarial loss (gain)	(11,000)	1,602,000	1,498,000
Net periodic benefit cost	(666,000)	1,537,000	2,589,000
Impact of PUC D&Os	1,976,000	(1,458,000)	(2,227,000)
Net periodic benefit cost (adjusted for impact of PUC D&Os)	1,310,000	79,000	362,000
Amounts amortized from AOCI or regulatory assets into net periodic pension benefit cost during 2015
Prior service credit	(1,800,000)
Net actuarial loss	1,700,000
Net transition obligation	0
Other benefits | Hawaiian Electric Company, Inc. and Subsidiaries
Defined benefit plans
Service cost	3,392,000	4,163,000	4,014,000
Interest cost	8,234,000	7,288,000	8,703,000
Expected return on plan assets	(10,739,000)	(10,002,000)	(10,195,000)
Amortization of net transition obligation	0	0	(9,000)
Amortization of net prior service (gain) cost	(1,804,000)	(1,803,000)	(1,803,000)
Amortization of net actuarial loss (gain)	0	1,544,000	1,455,000
Net periodic benefit cost	(917,000)	1,190,000	2,165,000
Impact of PUC D&Os	1,976,000	(1,458,000)	(2,227,000)
Net periodic benefit cost (adjusted for impact of PUC D&Os)	1,059,000	(268,000)	(62,000)
Amounts amortized from AOCI or regulatory assets into net periodic pension benefit cost during 2015
Prior service credit	(1,800,000)
Net actuarial loss	1,700,000
Net transition obligation	$ 0