Reconciliation of electric utility operating income per HEI and HECO consolidated statements of income (Details) - HECO (USD $) In Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Operating income from regulated and non-regulated activities before income taxes (per HEI consolidated statements of income)	$ 94,490	$ 72,631	$ 221,526	$ 196,969
Income taxes on regulated activities	(27,894)	(20,385)	(57,700)	(51,677)
Hawaiian Electric Company, Inc. and Subsidiaries
Income taxes on regulated activities	(23,860)	(14,818)	(46,630)	(36,972)
Operating income	49,999	36,114	113,258	97,371
Hawaiian Electric Company, Inc. and Subsidiaries \| Electric utility
Operating income from regulated and non-regulated activities before income taxes (per HEI consolidated statements of income)	74,956	51,343	162,682	135,387
Income taxes on regulated activities	(23,860)	(14,818)	(46,630)	(36,972)
Revenues from non-regulated activities	(1,347)	(903)	(3,467)	(4,303)
Add: Expenses from non-regulated activities	250	492	673	3,259
Operating income	49,999	36,114	113,258	97,371
Electric utility
Operating income from regulated and non-regulated activities before income taxes (per HEI consolidated statements of income)	74,956	51,343	162,682	135,387
Income taxes on regulated activities	$ (23,787)	$ (14,719)	$ (46,446)	$ (35,893)

Operating income (loss) after income tax expense (benefit) for the period.

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- Definition

The amount of unregulated operating expenses recognized during the period.

+ Details

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Namespace Prefix:	he
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Income Tax Expense (or Benefit)

-URI http://asc.fasb.org/extlink&oid=6515339

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (a),(b)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32639-109319

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph h

-Article 4

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 109

-Paragraph 45

-Subparagraph a, b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(h))

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

+ Details

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- Definition

The net result for the period of deducting operating expenses from operating revenues.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of unregulated operating revenues recognized during the period.

+ Details

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Data Type:	xbrli:monetaryItemType
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