Retirement benefits (Details) (USD $)	6 Months Ended		12 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended							12 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Pension benefits	Jun. 30, 2013 Pension benefits	Jun. 30, 2014 Pension benefits	Jun. 30, 2013 Pension benefits	Jun. 30, 2014 Other benefits	Jun. 30, 2013 Other benefits	Jun. 30, 2014 Other benefits	Jun. 30, 2013 Other benefits	Jun. 30, 2013 American Savings Bank (ASB) Other benefits	Jun. 30, 2014 Hawaiian Electric Industries, Inc. Other benefits	Jun. 30, 2013 Hawaiian Electric Industries, Inc. Other benefits	Jun. 30, 2014 HECO Consolidated	Jun. 30, 2013 HECO Consolidated	Dec. 31, 2013 HECO Consolidated	Jun. 30, 2014 HECO Consolidated Pension benefits	Jun. 30, 2013 HECO Consolidated Pension benefits	Jun. 30, 2014 HECO Consolidated Pension benefits	Jun. 30, 2013 HECO Consolidated Pension benefits	Jun. 30, 2014 HECO Consolidated Other benefits	Jun. 30, 2013 HECO Consolidated Other benefits	Jun. 30, 2014 HECO Consolidated Other benefits	Jun. 30, 2013 HECO Consolidated Other benefits
Defined benefit plans
Contributions made to defined benefit plans						$ 30,000,000	$ 42,000,000													$ 29,000,000	$ 41,000,000
Contributions expected to be paid in current year										60,000,000	83,000,000	0	1,000,000	2,000,000										59,000,000	81,000,000
Expected payments in 2014	2,000,000														1,000,000
Payments for benefits			2,000,000														1,000,000
Service cost				12,525,000	14,121,000	24,652,000	28,210,000	866,000	1,103,000	1,749,000	2,152,000							12,101,000	13,638,000	23,798,000	27,241,000	840,000	1,067,000	1,696,000	2,081,000
Interest cost				18,113,000	16,307,000	36,114,000	32,413,000	2,117,000	1,855,000	4,277,000	3,786,000							16,553,000	14,883,000	32,989,000	29,559,000	2,038,000	1,783,000	4,117,000	3,644,000
Expected return on plan assets				(20,334,000)	(18,182,000)	(40,681,000)	(36,267,000)	(2,748,000)	(2,521,000)	(5,456,000)	(5,083,000)							(18,158,000)	(16,185,000)	(36,329,000)	(32,275,000)	(2,707,000)	(2,480,000)	(5,370,000)	(5,000,000)
Amortization of prior service gain				22,000	(25,000)	44,000	(49,000)	(449,000)	(449,000)	(897,000)	(897,000)							16,000	(116,000)	31,000	(232,000)	(451,000)	(451,000)	(902,000)	(902,000)
Amortization of net actuarial loss				5,138,000	9,499,000	10,176,000	19,318,000	(3,000)	284,000	(6,000)	805,000							4,669,000	8,509,000	9,229,000	17,299,000	0	268,000	0	772,000
Net periodic benefit cost				15,464,000	21,720,000	30,305,000	43,625,000	(217,000)	272,000	(333,000)	763,000							15,181,000	20,729,000	29,718,000	41,592,000	(280,000)	187,000	(459,000)	595,000
Impact of PUC D&Os				(3,651,000)	(10,724,000)	(6,662,000)	(19,590,000)	543,000	(187,000)	988,000	(584,000)							(3,651,000)	(10,724,000)	(6,662,000)	(19,590,000)	543,000	(187,000)	988,000	(584,000)
Net periodic benefit cost (adjusted for impact of PUC D&Os)				11,813,000	10,996,000	23,643,000	24,035,000	326,000	85,000	655,000	179,000							11,530,000	10,005,000	23,056,000	22,002,000	263,000	0	529,000	11,000
Retirement benefits expense	17,000,000	18,000,000													16,000,000	15,000,000
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	2,200,000	2,000,000													400,000	300,000
Cash contributions by the employer to defined contribution plan	$ 3,500,000	$ 3,000,000													$ 400,000	$ 300,000