Quarterly information (unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jul. 19, 2016
Condensed Financial Statements, Captions [Line Items]
Revenues	$ 617,395,000	$ 646,055,000	$ 566,244,000	$ 550,960,000	$ 624,032,000	$ 717,176,000	$ 623,912,000	$ 637,862,000	$ 2,380,654,000	$ 2,602,982,000	$ 3,239,542,000
Operating income	88,427,000	105,442,000	85,455,000	68,851,000	83,222,000	97,095,000	72,730,000	69,506,000	348,175,000	322,553,000	332,600,000
Net income	45,107,000	127,613,000	44,601,000	32,825,000	42,793,000	51,144,000	35,491,000	32,339,000	250,146,000	161,767,000	170,019,000
Net income for common stock	$ 44,634,000	$ 127,142,000	$ 44,128,000	$ 32,352,000	$ 42,320,000	$ 50,673,000	$ 35,018,000	$ 31,866,000	$ 248,256,000	$ 159,877,000	$ 168,129,000
Basic earnings per common share (in dollars per share)	$ 0.41	$ 1.17	$ 0.41	$ 0.30	$ 0.39	$ 0.47	$ 0.33	$ 0.31	$ 2.30	$ 1.50	$ 1.65
Diluted earnings per common share (in dollars per share)	0.41	1.17	0.41	0.30	0.39	0.47	0.33	0.31	2.29	1.50	1.63
Dividends per common share (in dollars per share)	0.31	0.31	0.31	0.31	0.31	0.31	0.31	0.31	1.24	1.24	$ 1.24
Market price per common share
High end of range (in dollars per share)	34.08	33.57	34.98	32.69	30.29	31.28	32.58	34.86	34.98	34.86
Low end of range (in dollars per share)	$ 28.31	$ 29.14	$ 31.35	$ 27.30	$ 27.45	$ 27.02	$ 29.62	$ 31.75	$ 27.30	$ 27.02
NextEra Energy, Inc Merger
Market price per common share
Merger contract termination fee		$ 90,000,000										$ 90,000,000
Merger termination, merger expenses during the quarter		64,000,000	$ (2,000,000)	$ (2,000,000)	$ (2,000,000)	$ (2,000,000)	$ (7,000,000)	$ (5,000,000)	$ (6,000,000)	$ (16,000,000)	$ (5,000,000)
Hawaiian Electric Company, Inc. and Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Revenues	$ 544,668,000	572,253,000	495,395,000	482,052,000	555,434,000	648,127,000	558,163,000	573,442,000	2,094,368,000	2,335,166,000	2,987,323,000
Operating income	68,644,000	89,812,000	70,686,000	55,326,000	67,662,000	82,657,000	66,161,000	57,636,000	284,468,000	274,116,000	275,768,000
Net income	34,618,000	47,472,000	36,356,000	25,866,000	33,492,000	43,504,000	33,340,000	27,373,000	144,312,000	137,709,000	139,636,000
Net income for common stock	$ 34,119,000	$ 46,974,000	$ 35,857,000	$ 25,367,000	$ 32,993,000	$ 43,006,000	$ 32,841,000	$ 26,874,000	$ 142,317,000	$ 135,714,000	$ 137,641,000