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Electric utility segment (Details 6) (USD $) In Millions, unless otherwise specified |  | 3 Months Ended | 12 Months Ended |  | 12 Months Ended
--- | --- | --- | --- | --- | ---
Dec. 31, 2012 | Dec. 31, 2012 Hawaiian Electric Company, Inc. and Subsidiaries | Dec. 31, 2012 Hawaiian Electric Company, Inc. and Subsidiaries CIS project | Jan. 28, 2013 Hawaiian Electric Company, Inc. and Subsidiaries CIS project | Dec. 31, 2012 HECO CIS project | Dec. 31, 2012 HELCO CIS project | Dec. 31, 2012 MECO CIS project
Regulatory projects and legal obligations |  |  |  |  |  |  |
Project costs to be written off, subject to approval by PUC |  |  |  | $ 40 |  |  |
After-tax charge to net income due to write-off of project costs |  | 24.0 | 24.0 |  | 17.1 | 3.4 | 3.2
Remaining recoverable project costs included in rate base, in accordance with the settlement agreement | $ 52 |  |  |  |  |  |

X
- Definition Represents the amount of project costs to be written off, subject to an approval by Utilities Commission of the State of Hawaii. + References No definition available. + Details
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X
- Definition Represents the amount of after-tax charge to net income due to a writedown of project costs. + References No definition available. + Details
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- Details
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X
- Definition Represents the amount of remaining recoverable project costs included in rate base, in accordance with the settlement agreement. + References No definition available. + Details
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