Consolidating financial information (Details 3) - HECO (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011
Other long-term assets
Total assets	$ 10,238,145	$ 10,149,132
Capitalization
Cumulative preferred stock - not subject to mandatory redemption
Current liabilities
Interest and preferred dividends payable	25,503	26,258
Deferred credits and other liabilities
Deferred income taxes	474,197	439,329
Contributions in aid of construction	419,337	405,520
Total liabilities and shareholders' equity	10,238,145	10,149,132
HECO
Utility plant, at cost
Land	43,424	43,370
Plant and equipment	3,423,045	3,325,862
Less accumulated depreciation	(1,208,090)	(1,185,899)
Construction in progress	131,745	130,143
Net utility plant	2,390,124	2,313,476
Investment in wholly owned subsidiaries, at equity	503,388	497,939
Current assets
Cash and cash equivalents	4,914	8,265	2,423	44,819
Advances to affiliates	18,000	9,400
Customer accounts receivable, net	137,171	154,316
Accrued unbilled revenues, net	102,695	100,600
Other accounts receivable, net	15,027	33,313
Fuel oil stock, at average cost	84,748	123,176
Materials and supplies, at average cost	35,848	31,779
Prepayments and other	26,194	21,708
Regulatory assets	51,214	42,675
Total current assets	475,811	525,232
Other long-term assets
Regulatory assets	606,971	601,451
Unamortized debt expense	6,655	7,042
Other	45,995	46,586
Total other long-term assets	659,621	655,079
Total assets	4,028,944	3,991,726
Capitalization
Common stock equity	1,484,504	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	2,287,343	2,274,975
Current liabilities
Short-term borrowings from nonaffiliates	53,992
Short-term borrowings from affiliate	9,600	18,050
Accounts payable	101,725	134,651
Interest and preferred dividends payable	13,805	14,479
Taxes accrued	152,905	174,477
Other	51,807	47,203
Total current liabilities	383,834	388,860
Deferred credits and other liabilities
Deferred income taxes	330,551	302,569
Regulatory liabilities	222,193	218,437
Unamortized tax credits	42,396	39,827
Defined benefit pension and other postretirement benefit plans liability	449,039	459,765
Other	65,242	68,783
Total deferred credits and other liabilities	1,109,421	1,089,381
Contributions in aid of construction	248,346	238,510
Total liabilities and shareholders' equity	4,028,944	3,991,726
HELCO
Utility plant, at cost
Land	5,182	5,182
Plant and equipment	1,095,425	1,086,048
Less accumulated depreciation	(445,035)	(433,531)
Construction in progress	21,635	12,126
Net utility plant	677,207	669,825
Current assets
Cash and cash equivalents	3,401	5,441	2,934	3,383
Advances to affiliates	9,600	18,050
Customer accounts receivable, net	30,867	29,772
Accrued unbilled revenues, net	17,241	14,393
Other accounts receivable, net	2,308	1,122
Fuel oil stock, at average cost	9,673	15,485
Materials and supplies, at average cost	6,816	5,336
Prepayments and other	5,805	5,146
Regulatory assets	5,815	4,056
Total current assets	91,526	98,801
Other long-term assets
Regulatory assets	110,163	109,815
Unamortized debt expense	1,943	2,066
Other	9,281	9,871
Total other long-term assets	121,387	121,752
Total assets	890,120	890,378
Capitalization
Common stock equity	271,013	268,908
Cumulative preferred stock - not subject to mandatory redemption	7,000	7,000
Long-term debt, net	201,331	201,326
Total capitalization	479,344	477,234
Current liabilities
Accounts payable	23,747	27,457
Interest and preferred dividends payable	4,105	4,027
Taxes accrued	33,299	38,778
Other	9,564	10,310
Total current liabilities	70,715	80,572
Deferred credits and other liabilities
Deferred income taxes	74,285	68,479
Regulatory liabilities	70,171	67,359
Unamortized tax credits	13,508	13,450
Defined benefit pension and other postretirement benefit plans liability	78,265	80,686
Other	16,146	17,799
Total deferred credits and other liabilities	252,375	247,773
Contributions in aid of construction	87,686	84,799
Total liabilities and shareholders' equity	890,120	890,378
MECO
Utility plant, at cost
Land	3,016	3,016
Plant and equipment	973,648	952,490
Less accumulated depreciation	(429,407)	(421,359)
Construction in progress	13,522	9,109
Net utility plant	560,779	543,256
Current assets
Cash and cash equivalents	199	3,349	475	496
Customer accounts receivable, net	28,605	26,691
Accrued unbilled revenues, net	19,251	19,305
Other accounts receivable, net	1,420	3,016
Fuel oil stock, at average cost	23,024	22,758
Materials and supplies, at average cost	15,560	13,970
Prepayments and other	6,385	6,011
Regulatory assets	6,643	4,536
Total current assets	101,087	99,636
Other long-term assets
Regulatory assets	104,219	102,063
Unamortized debt expense	1,350	1,446
Other	14,984	14,848
Total other long-term assets	120,553	118,357
Total assets	782,419	761,249
Capitalization
Common stock equity	232,272	228,927
Cumulative preferred stock - not subject to mandatory redemption	5,000	5,000
Long-term debt, net	166,000	166,000
Total capitalization	403,272	399,927
Current liabilities
Short-term borrowings from affiliate	18,000	9,400
Accounts payable	25,405	24,716
Interest and preferred dividends payable	2,427	2,593
Taxes accrued	32,646	37,811
Other	25,291	14,634
Total current liabilities	103,769	89,154
Deferred credits and other liabilities
Deferred income taxes	52,116	46,563
Regulatory liabilities	34,890	36,278
Unamortized tax credits	13,622	13,307
Defined benefit pension and other postretirement benefit plans liability	77,722	79,754
Other	13,723	14,055
Total deferred credits and other liabilities	192,073	189,957
Contributions in aid of construction	83,305	82,211
Total liabilities and shareholders' equity	782,419	761,249
Other subsidiaries
Current assets
Cash and cash equivalents	103	104	105	108
Total current assets	103	104
Other long-term assets
Total assets	103	104
Capitalization
Common stock equity	103	104
Total capitalization	103	104
Deferred credits and other liabilities
Total liabilities and shareholders' equity	103	104
Consolidating adjustments
Utility plant, at cost
Investment in wholly owned subsidiaries, at equity	(503,388)	(497,939)
Current assets
Advances to affiliates	(27,600)	(27,450)
Other accounts receivable, net	(8,696)	(9,275)
Prepayments and other	(83)
Total current assets	(36,379)	(36,725)
Other long-term assets
Total assets	(539,767)	(534,664)
Capitalization
Common stock equity	(503,388)	(497,939)
Total capitalization	(503,388)	(497,939)
Current liabilities
Short-term borrowings from affiliate	(27,600)	(27,450)
Interest and preferred dividends payable	(12)	(7)
Other	(8,767)	(9,268)
Total current liabilities	(36,379)	(36,725)
Deferred credits and other liabilities
Total liabilities and shareholders' equity	(539,767)	(534,664)
HECO Consolidated
Utility plant, at cost
Land	51,622	51,568
Plant and equipment	5,492,118	5,364,400
Less accumulated depreciation	(2,082,532)	(2,040,789)
Construction in progress	166,902	151,378
Net utility plant	3,628,110	3,526,557
Current assets
Cash and cash equivalents	8,617	17,159	5,937	48,806
Customer accounts receivable, net	196,643	210,779
Accrued unbilled revenues, net	139,187	134,298
Other accounts receivable, net	10,059	28,176
Fuel oil stock, at average cost	117,445	161,419
Materials and supplies, at average cost	58,224	51,085
Prepayments and other	38,301	32,865
Regulatory assets	63,672	51,267
Total current assets	632,148	687,048
Other long-term assets
Regulatory assets	821,353	813,329
Unamortized debt expense	9,948	10,554
Other	70,260	71,305
Total other long-term assets	901,561	895,188
Total assets	5,161,819	5,108,793
Capitalization
Common stock equity	1,484,504	1,472,136
Cumulative preferred stock - not subject to mandatory redemption	34,293	34,293
Long-term debt, net	1,147,877	1,147,872
Total capitalization	2,666,674	2,654,301
Current liabilities
Short-term borrowings from nonaffiliates	53,992
Accounts payable	150,877	186,824
Interest and preferred dividends payable	20,325	21,092
Taxes accrued	218,850	251,066
Other	77,895	62,879
Total current liabilities	521,939	521,861
Deferred credits and other liabilities
Deferred income taxes	456,952	417,611
Regulatory liabilities	327,254	322,074
Unamortized tax credits	69,526	66,584
Defined benefit pension and other postretirement benefit plans liability	605,026	620,205
Other	95,111	100,637
Total deferred credits and other liabilities	1,553,869	1,527,111
Contributions in aid of construction	419,337	405,520
Total liabilities and shareholders' equity	$ 5,161,819	$ 5,108,793