Electric utility subsidiary - Consolidating statement of cash flows (Details 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities
Net income	$ 32,339us-gaap_ProfitLoss	$ 46,260us-gaap_ProfitLoss
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment	45,865us-gaap_Depreciation	43,181us-gaap_Depreciation
Other amortization	1,362us-gaap_AdjustmentForAmortization	1,609us-gaap_AdjustmentForAmortization
Increase in deferred income taxes	15,265us-gaap_DeferredIncomeTaxExpenseBenefit	6,457us-gaap_DeferredIncomeTaxExpenseBenefit
Allowance for equity funds used during construction	(1,413)	(1,609)
Change in cash overdraft	0	(1,038)
Changes in assets and liabilities
Decrease in fuel oil stock	20,731	(34,260)
Increase in regulatory assets	(10,827)	(9,258)
Change in prepaid and accrued income and utility revenue taxes	(61,397)	(19,474)
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability	123	(818)
Net cash provided by operating activities	76,650	19,421
Cash flows from investing activities
Capital expenditures	(59,011)	(65,829)
Contributions in aid of construction	9,145	6,958
Net cash used in investing activities	(87,797)	(74,232)
Cash flows from financing activities
Common stock dividends	(31,829)us-gaap_PaymentsOfDividendsCommonStock	(31,435)us-gaap_PaymentsOfDividendsCommonStock
Net increase (decrease) in short-term borrowings with original maturities of three months or less	(88,472)	30,887
Other	(6,253)	(3,953)
Net cash provided by financing activities	127,773	103,895
Net increase (decrease) in cash and cash equivalents	116,626	49,084
Hawaiian Electric Company
Cash flows from operating activities
Net income	27,144	35,690
Adjustments to reconcile net income to net cash provided by operating activities
Equity in earnings of subsidiaries	(7,717)	(8,942)
Common stock dividends received from subsidiaries	6,324	6,595
Depreciation of property, plant and equipment	29,389	27,301
Other amortization	590	235
Increase in deferred income taxes	12,048	17,123
Change in tax credits, net	2,246	1,741
Allowance for equity funds used during construction	(1,123)	(1,472)
Changes in assets and liabilities
Increase in accounts receivable	21,703	4,131
Decrease in accrued unbilled revenues	21,726	11,031
Decrease in fuel oil stock	8,654	(35,060)
Increase in materials and supplies	(1,115)	(330)
Increase in regulatory assets	(8,903)	(8,188)
Decrease in accounts payable	(35,128)	(837)
Change in prepaid and accrued income and utility revenue taxes	(52,273)	(39,581)
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability	0	(103)
Change in other assets and liabilities	(8,439)	(10,874)
Net cash provided by operating activities	15,126	(1,540)
Cash flows from investing activities
Capital expenditures	(40,594)	(49,432)
Contributions in aid of construction	8,121	4,541
Advances from affiliates	3,500	(12,661)
Net cash used in investing activities	(28,973)	(57,552)
Cash flows from financing activities
Common stock dividends	(22,601)	(22,707)
Preferred stock dividends of Hawaiian Electric and subsidiaries	(270)	(270)
Net increase (decrease) in short-term borrowings with original maturities of three months or less	30,000	34,096
Other	(214)	(320)
Net cash provided by financing activities	6,915	10,799
Net increase (decrease) in cash and cash equivalents	(6,932)	(48,293)
Cash and cash equivalents, beginning of period	12,416	61,245
Cash and cash equivalents, end of period	5,484	12,952
HELCO
Cash flows from operating activities
Net income	3,922	5,295
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment	9,313	8,975
Other amortization	500	501
Increase in deferred income taxes	719	862
Change in tax credits, net	200	217
Allowance for equity funds used during construction	(145)	(65)
Changes in assets and liabilities
Increase in accounts receivable	2,147	2,029
Decrease in accrued unbilled revenues	1,426	(230)
Decrease in fuel oil stock	5,817	1,166
Increase in materials and supplies	75	(387)
Increase in regulatory assets	(1,522)	(881)
Decrease in accounts payable	(9,892)	(6,032)
Change in prepaid and accrued income and utility revenue taxes	(1,807)	(2,791)
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability	0	0
Change in other assets and liabilities	229	1,041
Net cash provided by operating activities	10,982	9,700
Cash flows from investing activities
Capital expenditures	(7,558)	(7,530)
Contributions in aid of construction	758	1,121
Advances from affiliates	0	900
Net cash used in investing activities	(6,800)	(5,509)
Cash flows from financing activities
Common stock dividends	(2,505)	(2,941)
Preferred stock dividends of Hawaiian Electric and subsidiaries	(134)	(134)
Net increase (decrease) in short-term borrowings with original maturities of three months or less	(500)	0
Other	(1)	0
Net cash provided by financing activities	(3,140)	(3,075)
Net increase (decrease) in cash and cash equivalents	1,042	1,116
Cash and cash equivalents, beginning of period	612	1,326
Cash and cash equivalents, end of period	1,654	2,442
Maui Electric
Cash flows from operating activities
Net income	3,999	3,851
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment	5,541	5,327
Other amortization	(401)	885
Increase in deferred income taxes	2,365	2,359
Change in tax credits, net	130	74
Allowance for equity funds used during construction	(145)	(72)
Change in cash overdraft	0	(1,038)
Changes in assets and liabilities
Increase in accounts receivable	4,408	2,194
Decrease in accrued unbilled revenues	4,728	1,459
Decrease in fuel oil stock	6,260	(366)
Increase in materials and supplies	(317)	(328)
Increase in regulatory assets	(402)	(189)
Decrease in accounts payable	(4,116)	(9,155)
Change in prepaid and accrued income and utility revenue taxes	(9,616)	(5,154)
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability	110	(102)
Change in other assets and liabilities	534	(698)
Net cash provided by operating activities	13,078	(953)
Cash flows from investing activities
Capital expenditures	(6,206)	(7,500)
Contributions in aid of construction	266	1,296
Advances from affiliates	0	0
Net cash used in investing activities	(5,940)	(6,204)
Cash flows from financing activities
Common stock dividends	(3,794)	(3,629)
Preferred stock dividends of Hawaiian Electric and subsidiaries	(95)	(95)
Net increase (decrease) in short-term borrowings with original maturities of three months or less	(3,000)	12,661
Other	(1)	(69)
Net cash provided by financing activities	(6,890)	8,868
Net increase (decrease) in cash and cash equivalents	248	1,711
Cash and cash equivalents, beginning of period	633	153
Cash and cash equivalents, end of period	881	1,864
Other subsidiaries
Cash flows from operating activities
Net income	0	0
Changes in assets and liabilities
Net cash provided by operating activities	0	0
Cash flows from investing activities
Capital expenditures	0	0
Contributions in aid of construction	0	0
Advances from affiliates	0	0
Net cash used in investing activities	0	0
Cash flows from financing activities
Net increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	101	101
Cash and cash equivalents, end of period	101	101
Consolidating adjustments
Cash flows from operating activities
Net income	(7,692)	(8,917)
Adjustments to reconcile net income to net cash provided by operating activities
Equity in earnings of subsidiaries	7,692	8,917
Common stock dividends received from subsidiaries	(6,299)	(6,570)
Changes in assets and liabilities
Increase in accounts receivable	846	450
Change in other assets and liabilities	(846)	(450)
Net cash provided by operating activities	(6,299)	(6,570)
Cash flows from investing activities
Capital expenditures	0	0
Contributions in aid of construction	0	0
Advances from affiliates	(3,500)	11,761
Net cash used in investing activities	(3,500)	11,761
Cash flows from financing activities
Common stock dividends	6,299	6,570
Net increase (decrease) in short-term borrowings with original maturities of three months or less	3,500	(11,761)
Net cash provided by financing activities	9,799	(5,191)
Net increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	0	0
HECO Consolidated
Cash flows from operating activities
Net income	27,373	35,919
Adjustments to reconcile net income to net cash provided by operating activities
Equity in earnings of subsidiaries	(25)	(25)
Common stock dividends received from subsidiaries	25	25
Depreciation of property, plant and equipment	44,243	41,603
Other amortization	689	1,621
Increase in deferred income taxes	15,132	20,344
Change in tax credits, net	2,576	2,032
Allowance for equity funds used during construction	(1,413)	(1,609)
Change in cash overdraft	0	(1,038)
Changes in assets and liabilities
Increase in accounts receivable	29,104	8,804
Decrease in accrued unbilled revenues	27,880	12,260
Decrease in fuel oil stock	20,731	(34,260)
Increase in materials and supplies	(1,357)	(1,045)
Increase in regulatory assets	(10,827)	(9,258)
Decrease in accounts payable	(49,136)	(16,024)
Change in prepaid and accrued income and utility revenue taxes	(63,696)	(47,526)
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability	110	(205)
Change in other assets and liabilities	(8,522)	(10,981)
Net cash provided by operating activities	32,887	637
Cash flows from investing activities
Capital expenditures	(54,358)	(64,462)
Contributions in aid of construction	9,145	6,958
Advances from affiliates	0	0
Net cash used in investing activities	(45,213)	(57,504)
Cash flows from financing activities
Common stock dividends	(22,601)	(22,707)
Preferred stock dividends of Hawaiian Electric and subsidiaries	(499)	(499)
Net increase (decrease) in short-term borrowings with original maturities of three months or less	30,000	34,996
Other	(216)	(389)
Net cash provided by financing activities	6,684	11,401
Net increase (decrease) in cash and cash equivalents	(5,642)	(45,466)
Cash and cash equivalents, beginning of period	13,762	62,825
Cash and cash equivalents, end of period	$ 8,120	$ 17,359

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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The increase (decrease) during the reporting period in the aggregate amount of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business.

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The increase (decrease) during the reporting period in the value of other assets that are created when regulatory agencies permits public utilities to defer costs to the balance sheet.

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The change in cash during the period due to the net increase or decrease in outstanding checks, the liability that represents checks that have been issued but that have not cleared. The entity may classify these cash flows as financing or operating activities. Another element, Increase (Decrease) in Outstanding Checks, Financing Activities, represents cash flows from outstanding checks classified as financing activities.

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The increase (decrease) in cash associated with the entity's continuing operating, investing, and financing activities. While for technical reasons this element has no balance attribute, the default assumption is a debit balance consistent with its label.

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Amount of cash inflow (outflow) of investing activities, excluding discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

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Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity.

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Amount of cash outflow in the form of ordinary dividends to preferred shareholders of the parent entity.

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The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.

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The cash inflow from developers, builders, governmental agencies and municipalities that provide the entity with cash to extend its construction services to their properties.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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The component of the allowance for funds used during construction during the period based on an assumed rate of return on equity funds used in financing the construction of regulated assets.

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