Electric utility subsidiary - Consolidating financial statements (Details 3) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012
Utility plant, at cost
Total property, plant and equipment, net	$ 4,048,106	$ 3,865,514
Other long-term assets
Total assets	10,670,471	10,340,044
Capitalization
Common stock equity	1,801,408	1,727,070	1,655,465	1,593,865
Cumulative preferred stock — not subject to mandatory redemption	0	0
Current liabilities
Interest and preferred dividends payable	26,051	26,716
Deferred credits and other liabilities
Deferred income taxes	585,432	529,260
Contributions in aid of construction	448,811	432,894
Total liabilities and shareholders’ equity	10,670,471	10,340,044
Hawaiian Electric Company
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	5
Utility plant, at cost
Land	43,816	43,407
Plant and equipment	3,700,063	3,558,569
Less accumulated depreciation	(1,245,695)	(1,222,129)
Construction in progress	149,115	124,494
Utility property, plant and equipment, net	2,647,299	2,504,341
Nonutility property, plant and equipment, less accumulated depreciation	4,948	4,953
Total property, plant and equipment, net	2,652,247	2,509,294
Investment in wholly owned subsidiaries, at equity	532,766	523,674
Current assets
Cash and cash equivalents	14,856	61,245	18,906	8,265
Advances to affiliates	11,800	6,839
Customer accounts receivable, net	132,809	121,282
Accrued unbilled revenues, net	108,306	107,752
Other accounts receivable, net	22,386	16,373
Fuel oil stock, at average cost	88,285	99,613
Materials and supplies, at average cost	36,502	37,377
Prepayments and other	32,033	29,798
Regulatory assets	44,736	54,979
Total current assets	491,713	535,258
Other long-term assets
Regulatory assets	395,343	381,346
Unamortized debt expense	5,830	6,051
Other	42,203	42,163
Total other long-term assets	443,376	429,560
Total assets	4,120,102	3,997,786
Capitalization
Common stock equity	1,635,751	1,593,564	1,501,944	1,472,136
Cumulative preferred stock — not subject to mandatory redemption	22,293	22,293
Long-term debt, net	830,546	830,547
Total capitalization	2,488,590	2,446,404
Current liabilities
Short-term borrowings from non-affiliates	84,987
Short-term borrowings from affiliate	0	1,000
Accounts payable	107,108	145,062
Interest and preferred dividends payable	16,700	15,190
Taxes accrued	165,787	175,790
Regulatory liabilities	289	1,705
Other	46,727	48,443
Total current liabilities	421,598	387,190
Deferred credits and other liabilities
Deferred income taxes	404,144	359,621
Regulatory liabilities	244,830	235,786
Unamortized tax credits	49,609	44,931
Defined benefit pension and other postretirement benefit plans liability	192,246	202,396
Other	51,790	63,374
Total deferred credits and other liabilities	942,619	906,108
Contributions in aid of construction	267,295	258,084
Total liabilities and shareholders’ equity	4,120,102	3,997,786
HELCO
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	0
Utility plant, at cost
Land	5,464	5,460
Plant and equipment	1,165,542	1,136,923
Less accumulated depreciation	(472,044)	(453,721)
Construction in progress	13,267	7,709
Utility property, plant and equipment, net	712,229	696,371
Nonutility property, plant and equipment, less accumulated depreciation	82	82
Total property, plant and equipment, net	712,311	696,453
Current assets
Cash and cash equivalents	809	1,326	2,754	5,441
Advances to affiliates	0	1,000
Customer accounts receivable, net	31,023	28,088
Accrued unbilled revenues, net	16,474	17,100
Other accounts receivable, net	6,044	4,265
Fuel oil stock, at average cost	13,959	14,178
Materials and supplies, at average cost	7,870	6,883
Prepayments and other	6,112	8,334
Regulatory assets	4,855	6,931
Total current assets	87,146	88,105
Other long-term assets
Regulatory assets	66,004	64,552
Unamortized debt expense	1,485	1,580
Other	11,889	11,270
Total other long-term assets	79,378	77,402
Total assets	878,835	861,960
Capitalization
Common stock equity	279,388	274,802	272,860	268,908
Cumulative preferred stock — not subject to mandatory redemption	7,000	7,000
Long-term debt, net	190,000	189,998
Total capitalization	476,388	471,800
Current liabilities
Current portion of long-term debt	11,400	11,400
Short-term borrowings from affiliate	1,000
Accounts payable	27,077	24,383
Interest and preferred dividends payable	3,772	3,885
Taxes accrued	35,837	37,899
Regulatory liabilities	0	0
Other	10,596	9,033
Total current liabilities	89,682	86,600
Deferred credits and other liabilities
Deferred income taxes	84,905	79,947
Regulatory liabilities	79,389	76,475
Unamortized tax credits	14,914	14,245
Defined benefit pension and other postretirement benefit plans liability	26,435	28,427
Other	13,347	14,703
Total deferred credits and other liabilities	218,990	213,797
Contributions in aid of construction	93,775	89,763
Total liabilities and shareholders’ equity	878,835	861,960
Maui Electric
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	0
Utility plant, at cost
Land	3,064	3,016
Plant and equipment	1,036,792	1,006,383
Less accumulated depreciation	(449,806)	(435,379)
Construction in progress	16,808	11,030
Utility property, plant and equipment, net	606,858	585,050
Nonutility property, plant and equipment, less accumulated depreciation	1,531	1,532
Total property, plant and equipment, net	608,389	586,582
Current assets
Cash and cash equivalents	2,621	153	3,423	3,349
Customer accounts receivable, net	25,901	26,078
Accrued unbilled revenues, net	18,373	19,272
Other accounts receivable, net	3,070	2,451
Fuel oil stock, at average cost	16,059	20,296
Materials and supplies, at average cost	16,267	14,784
Prepayments and other	12,358	16,140
Regulatory assets	5,109	7,828
Total current assets	99,758	107,002
Other long-term assets
Regulatory assets	59,665	60,288
Unamortized debt expense	1,304	1,372
Other	13,799	13,993
Total other long-term assets	74,768	75,653
Total assets	782,915	769,237
Capitalization
Common stock equity	253,277	248,771	234,118	228,927
Cumulative preferred stock — not subject to mandatory redemption	5,000	5,000
Long-term debt, net	186,000	186,000
Total capitalization	444,277	439,771
Current liabilities
Short-term borrowings from affiliate	10,800	6,839
Accounts payable	17,793	20,114
Interest and preferred dividends payable	3,936	2,585
Taxes accrued	35,090	37,171
Regulatory liabilities	239	211
Other	17,062	15,424
Total current liabilities	84,920	82,344
Deferred credits and other liabilities
Deferred income taxes	76,450	67,593
Regulatory liabilities	32,343	35,122
Unamortized tax credits	14,745	14,363
Defined benefit pension and other postretirement benefit plans liability	29,657	31,339
Other	12,782	13,658
Total deferred credits and other liabilities	165,977	162,075
Contributions in aid of construction	87,741	85,047
Total liabilities and shareholders’ equity	782,915	769,237
Other subsidiaries
Current assets
Cash and cash equivalents	101	101	102	104
Total current assets	101	101
Other long-term assets
Total assets	101	101
Capitalization
Common stock equity	101	101	102	104
Total capitalization	101	101
Deferred credits and other liabilities
Total liabilities and shareholders’ equity	101	101
Consolidating adjustments
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	0
Utility plant, at cost
Investment in wholly owned subsidiaries, at equity	(532,766)	(523,674)
Current assets
Cash and cash equivalents			0	0
Advances to affiliates	(11,800)	(7,839)
Other accounts receivable, net	(11,992)	(9,027)
Prepayments and other	(233)	(1,415)
Total current assets	(24,025)	(18,281)
Other long-term assets
Total assets	(556,791)	(541,955)
Capitalization
Common stock equity	(532,766)	(523,674)	(507,080)	(497,939)
Total capitalization	(532,766)	(523,674)
Current liabilities
Short-term borrowings from affiliate	(11,800)	(7,839)
Interest and preferred dividends payable	(7)	(8)
Taxes accrued	(233)	(1,415)
Regulatory liabilities	0	0
Other	(11,985)	(9,019)
Total current liabilities	(24,025)	(18,281)
Deferred credits and other liabilities
Total liabilities and shareholders’ equity	(556,791)	(541,955)
HECO Consolidated
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	5
Utility plant, at cost
Land	52,344	51,883
Plant and equipment	5,902,397	5,701,875
Less accumulated depreciation	(2,167,545)	(2,111,229)
Construction in progress	179,190	143,233
Utility property, plant and equipment, net	3,966,386	3,785,762
Nonutility property, plant and equipment, less accumulated depreciation	6,561	6,567
Total property, plant and equipment, net	3,972,947	3,792,329
Current assets
Cash and cash equivalents	18,387	62,825	25,185	17,159
Customer accounts receivable, net	189,733	175,448
Accrued unbilled revenues, net	143,153	144,124
Other accounts receivable, net	19,508	14,062
Fuel oil stock, at average cost	118,303	134,087
Materials and supplies, at average cost	60,639	59,044
Prepayments and other	50,270	52,857
Regulatory assets	54,700	69,738
Total current assets	654,693	712,185
Other long-term assets
Regulatory assets	521,012	506,186
Unamortized debt expense	8,619	9,003
Other	67,891	67,426
Total other long-term assets	597,522	582,615
Total assets	5,225,162	5,087,129
Capitalization
Common stock equity	1,635,751	1,593,564	1,501,944	1,472,136
Cumulative preferred stock — not subject to mandatory redemption	34,293	34,293
Long-term debt, net	1,206,546	1,206,545
Total capitalization	2,876,590	2,834,402
Current liabilities
Current portion of long-term debt	11,400	11,400
Short-term borrowings from non-affiliates	84,987	0
Accounts payable	151,978	189,559
Interest and preferred dividends payable	24,401	21,652
Taxes accrued	236,481	249,445
Regulatory liabilities	528	1,916
Other	62,400	63,881
Total current liabilities	572,175	537,853
Deferred credits and other liabilities
Deferred income taxes	565,499	507,161
Regulatory liabilities	356,562	347,383
Unamortized tax credits	79,268	73,539
Defined benefit pension and other postretirement benefit plans liability	248,338	262,162
Other	77,919	91,735
Total deferred credits and other liabilities	1,327,586	1,281,980
Contributions in aid of construction	448,811	432,894
Total liabilities and shareholders’ equity	$ 5,225,162	$ 5,087,129