Reconciliation of electric utility operating income per HEI and HECO consolidated statements of income (Details) - HECO (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Operating income from regulated and nonregulated activities before income taxes (per HEI consolidated statements of income)	$ 70,657	$ 75,816
Income taxes on regulated activities	(18,662)	(21,298)
Electric utility
Operating income from regulated and nonregulated activities before income taxes (per HEI consolidated statements of income)	52,953	57,254
Income taxes on regulated activities	(14,394)	(17,408)
Hawaiian Electric Company, Inc. and Subsidiaries
Operating income	20,841	24,936
Hawaiian Electric Company, Inc. and Subsidiaries \| Electric utility
Operating income from regulated and nonregulated activities before income taxes (per HEI consolidated statements of income)	52,953	57,254
Income taxes on regulated activities	(14,095)	(17,365)
Revenues from nonregulated activities	(3,076)	(1,672)
Add: Expenses from nonregulated activities	764	364
Operating income	$ 36,546	$ 38,581

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

Reference 1: 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 2: 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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 3: 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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph h

-Article 4

Reference 5: 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

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