Consolidating financial information (Details 3) - HECO (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Other long-term assets
Total assets	$ 10,429,012	$ 10,149,132
Capitalization
Cumulative preferred stock - not subject to mandatory redemption	0	0
Current liabilities
Interest and preferred dividends payable	27,232	26,258
Deferred credits and other liabilities
Deferred income taxes	493,662	439,329
Contributions in aid of construction	425,916	405,520
Total liabilities and shareholders' equity	10,429,012	10,149,132
HECO
Utility plant, at cost
Land	43,392	43,370
Plant and equipment	3,488,617	3,325,862
Less accumulated depreciation	(1,211,045)	(1,185,899)
Construction in progress	122,399	130,143
Net utility plant	2,443,363	2,313,476
Investment in wholly owned subsidiaries, at equity	507,080	497,939
Current assets
Cash and cash equivalents	18,906	8,265	6,982	44,819
Advances to affiliates	23,000	9,400
Customer accounts receivable, net	134,641	154,316
Accrued unbilled revenues, net	104,981	100,600
Other accounts receivable, net	15,094	33,313
Fuel oil stock, at average cost	105,231	123,176
Materials and supplies, at average cost	37,171	31,779
Prepayments and other	26,024	21,708
Regulatory assets	36,006	42,675
Total current assets	501,054	525,232
Other long-term assets
Regulatory assets	626,209	601,451
Unamortized debt expense	6,491	7,042
Other	40,343	46,586
Total other long-term assets	673,043	655,079
Total assets	4,124,540	3,991,726
Capitalization
Common stock equity	1,501,944	1,472,136
Cumulative preferred stock - not subject to mandatory redemption	22,293	22,293
Long-term debt, net	780,546	780,546
Total capitalization	2,304,783	2,274,975
Current liabilities
Short-term borrowings from non-affiliates	73,246
Short-term borrowings from affiliate	7,000	18,050
Accounts payable	136,087	134,651
Interest and preferred dividends payable	15,097	14,479
Taxes accrued	163,204	174,477
Other	54,571	47,203
Total current liabilities	449,205	388,860
Deferred credits and other liabilities
Deferred income taxes	340,014	302,569
Regulatory liabilities	224,568	218,437
Unamortized tax credits	43,564	39,827
Defined benefit pension and other postretirement benefit plans liability	442,613	459,765
Other	67,157	68,783
Total deferred credits and other liabilities	1,117,916	1,089,381
Contributions in aid of construction	252,636	238,510
Total liabilities and shareholders' equity	4,124,540	3,991,726
HELCO
Utility plant, at cost
Land	5,426	5,182
Plant and equipment	1,116,702	1,086,048
Less accumulated depreciation	(449,547)	(433,531)
Construction in progress	14,120	12,126
Net utility plant	686,701	669,825
Current assets
Cash and cash equivalents	2,754	5,441	5,226	3,383
Advances to affiliates	7,000	18,050
Customer accounts receivable, net	29,569	29,772
Accrued unbilled revenues, net	16,120	14,393
Other accounts receivable, net	3,877	1,122
Fuel oil stock, at average cost	14,615	15,485
Materials and supplies, at average cost	7,042	5,336
Prepayments and other	4,413	5,146
Regulatory assets	4,636	4,056
Total current assets	90,026	98,801
Other long-term assets
Regulatory assets	112,244	109,815
Unamortized debt expense	1,882	2,066
Other	8,405	9,871
Total other long-term assets	122,531	121,752
Total assets	899,258	890,378
Capitalization
Common stock equity	272,860	268,908
Cumulative preferred stock - not subject to mandatory redemption	7,000	7,000
Long-term debt, net	201,334	201,326
Total capitalization	481,194	477,234
Current liabilities
Accounts payable	25,352	27,457
Interest and preferred dividends payable	3,949	4,027
Taxes accrued	35,403	38,778
Other	11,298	10,310
Total current liabilities	76,002	80,572
Deferred credits and other liabilities
Deferred income taxes	75,866	68,479
Regulatory liabilities	71,230	67,359
Unamortized tax credits	13,552	13,450
Defined benefit pension and other postretirement benefit plans liability	77,004	80,686
Other	15,386	17,799
Total deferred credits and other liabilities	253,038	247,773
Contributions in aid of construction	89,024	84,799
Total liabilities and shareholders' equity	899,258	890,378
MECO
Utility plant, at cost
Land	3,016	3,016
Plant and equipment	988,482	952,490
Less accumulated depreciation	(432,983)	(421,359)
Construction in progress	14,558	9,109
Net utility plant	573,073	543,256
Current assets
Cash and cash equivalents	3,423	3,349	3,409	496
Customer accounts receivable, net	23,494	26,691
Accrued unbilled revenues, net	18,800	19,305
Other accounts receivable, net	2,214	3,016
Fuel oil stock, at average cost	17,241	22,758
Materials and supplies, at average cost	15,221	13,970
Prepayments and other	14,939	6,011
Regulatory assets	5,081	4,536
Total current assets	100,413	99,636
Other long-term assets
Regulatory assets	106,243	102,063
Unamortized debt expense	1,301	1,446
Other	13,919	14,848
Total other long-term assets	121,463	118,357
Total assets	794,949	761,249
Capitalization
Common stock equity	234,118	228,927
Cumulative preferred stock - not subject to mandatory redemption	5,000	5,000
Long-term debt, net	166,000	166,000
Total capitalization	405,118	399,927
Current liabilities
Short-term borrowings from affiliate	23,000	9,400
Accounts payable	19,518	24,716
Interest and preferred dividends payable	3,363	2,593
Taxes accrued	34,846	37,811
Other	24,664	14,634
Total current liabilities	105,391	89,154
Deferred credits and other liabilities
Deferred income taxes	62,721	46,563
Regulatory liabilities	33,333	36,278
Unamortized tax credits	13,922	13,307
Defined benefit pension and other postretirement benefit plans liability	76,623	79,754
Other	13,585	14,055
Total deferred credits and other liabilities	200,184	189,957
Contributions in aid of construction	84,256	82,211
Total liabilities and shareholders' equity	794,949	761,249
Other subsidiaries
Current assets
Cash and cash equivalents	102	104	105	108
Total current assets	102	104
Other long-term assets
Total assets	102	104
Capitalization
Common stock equity	102	104
Total capitalization	102	104
Deferred credits and other liabilities
Total liabilities and shareholders' equity	102	104
Consolidating adjustments
Utility plant, at cost
Investment in wholly owned subsidiaries, at equity	(507,080)	(497,939)
Current assets
Advances to affiliates	(30,000)	(27,450)
Other accounts receivable, net	(12,011)	(9,275)
Prepayments and other	0
Total current assets	(42,011)	(36,725)
Other long-term assets
Total assets	(549,091)	(534,664)
Capitalization
Common stock equity	(507,080)	(497,939)
Total capitalization	(507,080)	(497,939)
Current liabilities
Short-term borrowings from affiliate	(30,000)	(27,450)
Interest and preferred dividends payable	(12)	(7)
Other	(11,999)	(9,268)
Total current liabilities	(42,011)	(36,725)
Deferred credits and other liabilities
Total liabilities and shareholders' equity	(549,091)	(534,664)
HECO Consolidated
Utility plant, at cost
Land	51,834	51,568
Plant and equipment	5,593,801	5,364,400
Less accumulated depreciation	(2,093,575)	(2,040,789)
Construction in progress	151,077	151,378
Net utility plant	3,703,137	3,526,557
Current assets
Cash and cash equivalents	25,185	17,159	15,722	48,806
Customer accounts receivable, net	187,704	210,779
Accrued unbilled revenues, net	139,901	134,298
Other accounts receivable, net	9,174	28,176
Fuel oil stock, at average cost	137,087	161,419
Materials and supplies, at average cost	59,434	51,085
Prepayments and other	45,376	32,865
Regulatory assets	45,723	51,267
Total current assets	649,584	687,048
Other long-term assets
Regulatory assets	844,696	813,329
Unamortized debt expense	9,674	10,554
Other	62,667	71,305
Total other long-term assets	917,037	895,188
Total assets	5,269,758	5,108,793
Capitalization
Common stock equity	1,501,944	1,472,136
Cumulative preferred stock - not subject to mandatory redemption	34,293	34,293
Long-term debt, net	1,147,880	1,147,872
Total capitalization	2,684,117	2,654,301
Current liabilities
Short-term borrowings from non-affiliates	73,246	0
Accounts payable	180,957	186,824
Interest and preferred dividends payable	22,397	21,092
Taxes accrued	233,453	251,066
Other	78,534	62,879
Total current liabilities	588,587	521,861
Deferred credits and other liabilities
Deferred income taxes	478,601	417,611
Regulatory liabilities	329,131	322,074
Unamortized tax credits	71,038	66,584
Defined benefit pension and other postretirement benefit plans liability	596,240	620,205
Other	96,128	100,637
Total deferred credits and other liabilities	1,571,138	1,527,111
Contributions in aid of construction	425,916	405,520
Total liabilities and shareholders' equity	$ 5,269,758	$ 5,108,793