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Subsequent events (Details) - HECO (Hawaiian Electric Company, Inc. and Subsidiaries, USD $) In Millions, unless otherwise specified | 1 Months Ended |  | 12 Months Ended |
--- | --- | --- | --- | ---
Jul. 31, 2011 RAM | Jul. 22, 2011 RAM | Dec. 31, 2013 | Jul. 22, 2011
Subsequent Events |  |  |  |
Increase in annual revenues, net of RAM |  | $ 38.2 |  |
Increase in annual revenues, including RAM |  |  |  | $ 53.2
Percentage of increase in net of revenues (as a percent) | 2.20% |  | 3.10% |

X
- Definition Represents the amount of net increase in annual revenues. + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Represents the amount of net increase in annual revenues, net of RAM. + Details
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Namespace Prefix: | he
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the percentage of increases in net annual revenues. + Details
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Namespace Prefix: | he
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + Details
Name: | us-gaap_SubsequentEventLineItems
Namespace Prefix: | us-gaap
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration