Electric utility subsidiary - Consolidating balance sheet (Details 3) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Utility plant, at cost
Total property, plant and equipment, net	$ 4,190,835	$ 4,148,774
Other long-term assets
Total assets	11,273,447	11,185,142
Capitalization
Common stock equity	1,897,909	1,790,573	1,745,124	1,726,406
Cumulative preferred stock — not subject to mandatory redemption	0	0
Current liabilities
Interest and preferred dividends payable	25,225	25,336
Deferred credits and other liabilities
Deferred income taxes	640,778	633,570
Contributions in aid of construction	474,385	466,432
Total liabilities and shareholders’ equity	11,273,447	11,185,142
Hawaiian Electric Company
Utility plant, at cost
Land	43,542	43,819
Plant and equipment	3,826,826	3,782,438
Less accumulated depreciation	(1,256,950)	(1,253,866)
Construction in progress	135,984	134,376
Utility property, plant and equipment, net	2,749,402	2,706,767
Nonutility property, plant and equipment, less accumulated depreciation	4,949	4,950
Total property, plant and equipment, net	2,754,351	2,711,717
Investment in wholly owned subsidiaries, at equity	540,032	538,639
Current assets
Cash and cash equivalents	5,484	12,416	12,952	61,245
Advances to affiliates	12,600	16,100
Customer accounts receivable, net	86,157	111,462
Accrued unbilled revenues, net	81,346	103,072
Other accounts receivable, net	13,582	9,980
Fuel oil stock, at average cost	65,861	74,515
Materials and supplies, at average cost	34,269	33,154
Prepayments and other	31,970	44,680
Regulatory assets	85,353	58,550
Total current assets	416,622	463,929
Other long-term assets
Regulatory assets	598,535	623,784
Unamortized debt expense	5,621	5,640
Other	53,370	53,106
Total other long-term assets	657,526	682,530
Total assets	4,368,531	4,396,815
Capitalization
Common stock equity	1,686,434	1,682,144	1,606,283	1,593,564
Cumulative preferred stock — not subject to mandatory redemption	22,293	22,293
Long-term debt, net	830,546	830,546
Total capitalization	2,539,273	2,534,983
Current liabilities
Short-term borrowings from non-affiliates	30,000
Short-term borrowings from affiliate	0	0
Accounts payable	106,975	122,433
Interest and preferred dividends payable	16,678	15,407
Taxes accrued	126,742	176,339
Regulatory liabilities	681	191
Other	49,389	48,282
Total current liabilities	330,465	362,652
Deferred credits and other liabilities
Deferred income taxes	423,151	429,515
Regulatory liabilities	240,749	236,727
Unamortized tax credits	52,093	49,865
Defined benefit pension and other postretirement benefit plans liability	443,249	446,888
Other	48,044	52,446
Total deferred credits and other liabilities	1,207,286	1,215,441
Contributions in aid of construction	291,507	283,739
Total liabilities and shareholders’ equity	4,368,531	4,396,815
HELCO
Utility plant, at cost
Land	5,464	5,464
Plant and equipment	1,182,567	1,179,032
Less accumulated depreciation	(478,692)	(473,933)
Construction in progress	14,947	12,421
Utility property, plant and equipment, net	724,286	722,984
Nonutility property, plant and equipment, less accumulated depreciation	82	82
Total property, plant and equipment, net	724,368	723,066
Current assets
Cash and cash equivalents	1,654	612	2,442	1,326
Advances to affiliates	0	0
Customer accounts receivable, net	21,485	24,222
Accrued unbilled revenues, net	14,500	15,926
Other accounts receivable, net	1,571	981
Fuel oil stock, at average cost	7,983	13,800
Materials and supplies, at average cost	6,589	6,664
Prepayments and other	230	8,611
Regulatory assets	9,359	6,745
Total current assets	63,371	77,561
Other long-term assets
Regulatory assets	104,663	107,454
Unamortized debt expense	1,396	1,438
Other	15,689	15,366
Total other long-term assets	121,748	124,258
Total assets	909,487	924,885
Capitalization
Common stock equity	283,129	281,846	277,022	274,802
Cumulative preferred stock — not subject to mandatory redemption	7,000	7,000
Long-term debt, net	190,000	190,000
Total capitalization	480,129	478,846
Current liabilities
Current portion of long-term debt	0
Short-term borrowings from affiliate	10,000	10,500
Accounts payable	14,988	23,728
Interest and preferred dividends payable	3,560	3,989
Taxes accrued	30,060	37,548
Regulatory liabilities	0	0
Other	10,126	9,866
Total current liabilities	68,734	85,631
Deferred credits and other liabilities
Deferred income taxes	89,923	90,119
Regulatory liabilities	79,504	77,707
Unamortized tax credits	15,096	14,902
Defined benefit pension and other postretirement benefit plans liability	68,989	72,547
Other	12,664	10,658
Total deferred credits and other liabilities	266,176	265,933
Contributions in aid of construction	94,448	94,475
Total liabilities and shareholders’ equity	909,487	924,885
Maui Electric
Utility plant, at cost
Land	3,016	3,016
Plant and equipment	1,057,130	1,048,012
Less accumulated depreciation	(453,448)	(447,711)
Construction in progress	13,920	11,819
Utility property, plant and equipment, net	620,618	615,136
Nonutility property, plant and equipment, less accumulated depreciation	1,531	1,531
Total property, plant and equipment, net	622,149	616,667
Current assets
Cash and cash equivalents	881	633	1,864	153
Customer accounts receivable, net	17,353	22,800
Accrued unbilled revenues, net	13,648	18,376
Other accounts receivable, net	3,285	2,246
Fuel oil stock, at average cost	11,471	17,731
Materials and supplies, at average cost	17,749	17,432
Prepayments and other	12,534	13,567
Regulatory assets	8,033	6,126
Total current assets	84,954	98,911
Other long-term assets
Regulatory assets	99,749	102,788
Unamortized debt expense	1,199	1,245
Other	13,214	13,366
Total other long-term assets	114,162	117,399
Total assets	821,265	832,977
Capitalization
Common stock equity	256,802	256,692	248,897	248,771
Cumulative preferred stock — not subject to mandatory redemption	5,000	5,000
Long-term debt, net	186,000	186,000
Total capitalization	447,802	447,692
Current liabilities
Short-term borrowings from affiliate	2,600	5,600
Accounts payable	16,546	17,773
Interest and preferred dividends payable	4,029	2,931
Taxes accrued	27,449	36,807
Regulatory liabilities	493	441
Other	16,234	16,094
Total current liabilities	67,351	79,646
Deferred credits and other liabilities
Deferred income taxes	83,910	83,238
Regulatory liabilities	30,388	29,966
Unamortized tax credits	14,848	14,725
Defined benefit pension and other postretirement benefit plans liability	74,927	75,960
Other	13,609	13,532
Total deferred credits and other liabilities	217,682	217,421
Contributions in aid of construction	88,430	88,218
Total liabilities and shareholders’ equity	821,265	832,977
Other subsidiaries
Current assets
Cash and cash equivalents	101	101	101	101
Total current assets	101	101
Other long-term assets
Total assets	101	101
Capitalization
Common stock equity	101	101	101	101
Total capitalization	101	101
Deferred credits and other liabilities
Total liabilities and shareholders’ equity	101	101
Consolidating adjustments
Utility plant, at cost
Investment in wholly owned subsidiaries, at equity	(540,032)	(538,639)
Current assets
Cash and cash equivalents	0	0	0	0
Advances to affiliates	(12,600)	(16,100)
Other accounts receivable, net	(9,770)	(8,924)
Prepayments and other	(1,379)	(475)
Total current assets	(23,749)	(25,499)
Other long-term assets
Regulatory assets	(103)	(183)
Total other long-term assets	(103)	(183)
Total assets	(563,884)	(564,321)
Capitalization
Common stock equity	(540,032)	(538,639)	(526,020)	(523,674)
Total capitalization	(540,032)	(538,639)
Current liabilities
Short-term borrowings from affiliate	(12,600)	(16,100)
Interest and preferred dividends payable	(10)	(11)
Taxes accrued	(1,379)	(292)
Regulatory liabilities	0	0
Other	(9,760)	(9,096)
Total current liabilities	(23,749)	(25,499)
Deferred credits and other liabilities
Regulatory liabilities	(103)	(183)
Total deferred credits and other liabilities		(183)
Total liabilities and shareholders’ equity	(563,884)	(564,321)
HECO Consolidated
Utility plant, at cost
Land	52,022	52,299
Plant and equipment	6,066,523	6,009,482
Less accumulated depreciation	(2,189,090)	(2,175,510)
Construction in progress	164,851	158,616
Utility property, plant and equipment, net	4,094,306	4,044,887
Nonutility property, plant and equipment, less accumulated depreciation	6,562	6,563
Total property, plant and equipment, net	4,100,868	4,051,450
Current assets
Cash and cash equivalents	8,120	13,762	17,359	62,825
Customer accounts receivable, net	124,995	158,484
Accrued unbilled revenues, net	109,494	137,374
Other accounts receivable, net	8,668	4,283
Fuel oil stock, at average cost	85,315	106,046
Materials and supplies, at average cost	58,607	57,250
Prepayments and other	43,355	66,383
Regulatory assets	102,745	71,421
Total current assets	541,299	615,003
Other long-term assets
Regulatory assets	802,844	833,843
Unamortized debt expense	8,216	8,323
Other	82,273	81,838
Total other long-term assets	893,333	924,004
Total assets	5,535,500	5,590,457
Capitalization
Common stock equity	1,686,434	1,682,144	1,606,283	1,593,564
Cumulative preferred stock — not subject to mandatory redemption	34,293	34,293
Long-term debt, net	1,206,546	1,206,546
Total capitalization	2,927,273	2,922,983
Current liabilities
Current portion of long-term debt	0
Short-term borrowings from non-affiliates	30,000	0
Accounts payable	138,509	163,934
Interest and preferred dividends payable	24,257	22,316
Taxes accrued	182,872	250,402
Regulatory liabilities	1,174	632
Other	65,989	65,146
Total current liabilities	442,801	502,430
Deferred credits and other liabilities
Deferred income taxes	596,984	602,872
Regulatory liabilities	350,538	344,217
Unamortized tax credits	82,037	79,492
Defined benefit pension and other postretirement benefit plans liability	587,165	595,395
Other	74,317	76,636
Total deferred credits and other liabilities	1,691,041	1,698,612
Contributions in aid of construction	474,385	466,432
Total liabilities and shareholders’ equity	$ 5,535,500	$ 5,590,457