Consolidating financial information (Details 3) - HECO (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Other long-term assets
Total assets	$ 9,821,957	$ 9,594,477
Capitalization
Cumulative preferred stock - not subject to mandatory redemption
Current liabilities
Interest and preferred dividends payable	24,897	25,041
Deferred credits and other liabilities
Deferred income taxes	396,806	354,051
Contributions in aid of construction	381,206	356,203
Total liabilities and shareholders' equity	9,821,957	9,594,477
HECO
Utility plant, at cost
Land	43,339	43,316
Plant and equipment	3,175,570	3,091,908
Less accumulated depreciation	(1,160,195)	(1,141,839)
Construction in progress	144,388	117,625
Net utility plant	2,203,102	2,111,010
Investment in wholly owned subsidiaries, at equity	521,966	516,143
Current assets
Cash and cash equivalents	2,423	44,819	23,287	121,019
Advances to affiliates	8,700
Customer accounts receivable, net	143,580	130,190
Accrued unbilled revenues, net	124,602	103,328
Other accounts receivable, net	13,250	8,987
Fuel oil stock, at average cost	156,942	128,037
Materials and supplies, at average cost	31,268	25,096
Prepayments and other	26,934	22,517
Regulatory assets	27,862	18,038
Total current assets	535,561	481,012
Other long-term assets
Regulatory assets	493,784	478,851
Unamortized debt expense	7,600	8,446
Other	59,708	58,672
Total other long-term assets	561,092	545,969
Total assets	3,821,721	3,654,134
Capitalization
Common stock equity	1,423,148	1,402,841
Cumulative preferred stock - not subject to mandatory redemption	22,293	22,293
Long-term debt, net	780,334	629,757
Total capitalization	2,225,775	2,054,891
Current liabilities
Current portion of long-term debt		42,580
Short-term borrowings - nonaffiliates	44,242
Short-term borrowings-affiliate	19,350	64,650
Accounts payable	164,002	140,044
Interest and preferred dividends payable	12,774	12,648
Taxes accrued	150,611	155,867
Other	40,451	50,828
Total current liabilities	431,430	466,617
Deferred credits and other liabilities
Deferred income taxes	268,645	236,890
Regulatory liabilities	215,648	215,401
Unamortized tax credits	37,489	34,877
Retirement benefits liability	344,998	368,245
Other	69,077	72,418
Total deferred credits and other liabilities	935,857	927,831
Contributions in aid of construction	228,659	204,795
Total liabilities and shareholders' equity	3,821,721	3,654,134
HELCO
Utility plant, at cost
Land	5,182	5,182
Plant and equipment	1,056,182	1,048,599
Less accumulated depreciation	(425,683)	(414,769)
Construction in progress	15,063	8,144
Net utility plant	650,744	647,156
Current assets
Cash and cash equivalents	2,934	3,383	1,844	1,229
Advances to affiliates	19,350	46,150
Customer accounts receivable, net	29,989	28,602
Accrued unbilled revenues, net	24,955	18,499
Other accounts receivable, net	(64)	1,186
Fuel oil stock, at average cost	19,731	19,217
Materials and supplies, at average cost	5,722	4,700
Prepayments and other	8,641	6,948
Regulatory assets	1,241	1,115
Total current assets	112,499	129,800
Other long-term assets
Regulatory assets	87,494	86,394
Unamortized debt expense	2,157	2,464
Other	14,397	11,843
Total other long-term assets	104,048	100,701
Total assets	867,291	877,657
Capitalization
Common stock equity	285,014	280,468
Cumulative preferred stock - not subject to mandatory redemption	7,000	7,000
Long-term debt, net	201,319	204,110
Total capitalization	493,333	491,578
Current liabilities
Current portion of long-term debt		7,200
Accounts payable	22,404	29,616
Interest and preferred dividends payable	4,046	4,074
Taxes accrued	34,504	38,598
Other	11,972	9,478
Total current liabilities	72,926	88,966
Deferred credits and other liabilities
Deferred income taxes	66,908	61,044
Regulatory liabilities	64,846	62,049
Unamortized tax credits	13,065	12,951
Retirement benefits liability	57,915	62,036
Other	20,583	22,391
Total deferred credits and other liabilities	223,317	220,471
Contributions in aid of construction	77,715	76,642
Total liabilities and shareholders' equity	867,291	877,657
MECO
Utility plant, at cost
Land	3,016	3,016
Plant and equipment	924,571	911,520
Less accumulated depreciation	(418,587)	(410,286)
Construction in progress	13,535	13,069
Net utility plant	522,535	517,319
Current assets
Cash and cash equivalents	475	496	291	594
Advances to affiliates		18,500
Customer accounts receivable, net	26,875	24,536
Accrued unbilled revenues, net	20,322	15,999
Other accounts receivable, net	1,371	3,008
Fuel oil stock, at average cost	30,768	24,294
Materials and supplies, at average cost	13,797	13,392
Prepayments and other	7,826	7,343
Regulatory assets	1,269	1,130
Total current assets	102,703	108,698
Other long-term assets
Regulatory assets	86,798	83,861
Unamortized debt expense	1,510	1,876
Other	16,995	15,846
Total other long-term assets	105,303	101,583
Total assets	730,541	727,600
Capitalization
Common stock equity	236,847	235,568
Cumulative preferred stock - not subject to mandatory redemption	5,000	5,000
Long-term debt, net	166,000	166,703
Total capitalization	407,847	407,271
Current liabilities
Current portion of long-term debt		7,720
Short-term borrowings-affiliate	8,700
Accounts payable	20,078	18,920
Interest and preferred dividends payable	2,203	2,762
Taxes accrued	32,206	35,752
Other	15,107	13,603
Total current liabilities	78,294	78,757
Deferred credits and other liabilities
Deferred income taxes	44,931	39,929
Regulatory liabilities	37,464	38,016
Unamortized tax credits	12,883	12,786
Retirement benefits liability	60,717	64,840
Other	13,573	11,235
Total deferred credits and other liabilities	169,568	166,806
Contributions in aid of construction	74,832	74,766
Total liabilities and shareholders' equity	730,541	727,600
RHI
Current assets
Cash and cash equivalents	80	82	85	89
Total current assets	80	82
Other long-term assets
Total assets	80	82
Capitalization
Common stock equity	80	81
Total capitalization	80	81
Current liabilities
Other		1
Total current liabilities		1
Deferred credits and other liabilities
Total liabilities and shareholders' equity	80	82
UBC
Current assets
Cash and cash equivalents	25	26	27	5
Total current assets	25	26
Other long-term assets
Total assets	25	26
Capitalization
Common stock equity	25	26
Total capitalization	25	26
Deferred credits and other liabilities
Total liabilities and shareholders' equity	25	26
Reclassifications and eliminations
Utility plant, at cost
Investment in wholly owned subsidiaries, at equity	(521,966)	(516,143)
Current assets
Advances to affiliates	(28,050)	(64,650)
Other accounts receivable, net	(12,092)	(4,558)
Prepayments and other		(141)
Total current assets	(40,142)	(69,349)
Other long-term assets
Total assets	(562,108)	(585,492)
Capitalization
Common stock equity	(521,966)	(516,143)
Total capitalization	(521,966)	(516,143)
Current liabilities
Short-term borrowings-affiliate	(28,050)	(64,650)
Interest and preferred dividends payable	(9)	(1)
Taxes accrued		(141)
Other	(12,083)	(4,557)
Total current liabilities	(40,142)	(69,349)
Deferred credits and other liabilities
Total liabilities and shareholders' equity	(562,108)	(585,492)
HECO Consolidated
Utility plant, at cost
Land	51,537	51,514
Plant and equipment	5,156,323	5,052,027
Less accumulated depreciation	(2,004,465)	(1,966,894)
Construction in progress	172,986	138,838
Net utility plant	3,376,381	3,275,485
Current assets
Cash and cash equivalents	5,937	48,806	25,534	122,936
Customer accounts receivable, net	200,444	183,328
Accrued unbilled revenues, net	169,879	137,826
Other accounts receivable, net	2,465	8,623
Fuel oil stock, at average cost	207,441	171,548
Materials and supplies, at average cost	50,787	43,188
Prepayments and other	43,401	36,667
Regulatory assets	30,372	20,283
Total current assets	710,726	650,269
Other long-term assets
Regulatory assets	668,076	649,106
Unamortized debt expense	11,267	12,786
Other	91,100	86,361
Total other long-term assets	770,443	748,253
Total assets	4,857,550	4,674,007
Capitalization
Common stock equity	1,423,148	1,402,841		1,334,155
Cumulative preferred stock - not subject to mandatory redemption	34,293	34,293
Long-term debt, net	1,147,653	1,000,570
Total capitalization	2,605,094	2,437,704
Current liabilities
Current portion of long-term debt		57,500
Short-term borrowings - nonaffiliates	44,242
Accounts payable	206,484	188,580
Interest and preferred dividends payable	19,014	19,483
Taxes accrued	217,321	230,076
Other	55,447	69,353
Total current liabilities	542,508	564,992
Deferred credits and other liabilities
Deferred income taxes	380,484	337,863
Regulatory liabilities	317,958	315,466
Unamortized tax credits	63,437	60,614
Retirement benefits liability	463,630	495,121
Other	103,233	106,044
Total deferred credits and other liabilities	1,328,742	1,315,108
Contributions in aid of construction	381,206	356,203
Total liabilities and shareholders' equity	$ 4,857,550	$ 4,674,007