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Electric utility segment Additional Information (Details) |  |  |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 30, 2014 | Jun. 30, 2014 | Jul. 11, 2013 MW | May. 31, 2013 USD ($) | Nov. 30, 2013 USD ($) | Feb. 28, 2013 bid | May. 31, 2012 MW | Mar. 31, 2012 USD ($) | Feb. 28, 2012 USD ($) | Dec. 31, 2009 | Nov. 30, 2013 USD ($) | Jun. 30, 2013 USD ($) | Dec. 31, 2011 USD ($) | Dec. 31, 2014 USD ($) agreement MW | Dec. 31, 2013 USD ($) MW | Dec. 31, 2012 USD ($) | Jul. 31, 2014 USD ($) | Feb. 07, 2014 | Feb. 16, 2012 generation_unit
Power purchase agreements |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of power purchase agreements (PPAs) | agreement |  |  |  |  |  |  |  |  |  |  |  |  |  | 7 |  |  |  |  |
Hawaiian Electric Company, Inc (HECO) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Power purchase agreements |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of power purchase agreements (PPAs) | agreement |  |  |  |  |  |  |  |  |  |  |  |  |  | 7 |  |  |  |  |
Purchased power |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 537,821,000 | $ 527,839,000 | $ 540,802,000 |  |  |
Renewable projects |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Generating Units Subject to New Regulation | generation_unit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 14
D&O |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,142,245,000 | 2,124,174,000 | 2,228,233,000 |  |  |
Hawaii Electric Light Company, Inc. (HELCO) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Power purchase agreements |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Purchased power |  |  |  |  |  |  |  |  |  |  |  |  |  | 123,226,000 | 128,368,000 | 145,386,000 |  |  |
D&O |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  | 422,200,000 | 431,517,000 | 441,013,000 |  |  |
Maui Electric Company, Limited (MECO) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Power purchase agreements |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Purchased power |  |  |  |  |  |  |  |  |  |  |  |  |  | 60,961,000 | 54,474,000 | 38,052,000 |  |  |
Environmental regulation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Additional accrued investigation and estimated cleanup costs |  |  |  |  |  |  |  | $ 3,100,000 |  |  |  |  |  | 3,600,000 |  |  |  |  |
D&O |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  | $ 5,300,000 |  |  |  |  |  |  |  |  |  | 422,965,000 | 424,603,000 | 440,270,000 |  |  |
Reductions in D&O |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lower ROACE |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,000,000 |  |  |  |
Customer Information System expenses |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 300,000 |  |  |  |
Pension and OPEB expense based on 3-year average |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,500,000 |  |  |  |
Integrated resource planning expenses |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 900,000 |  |  |  |
Operational and Renewable Energy Integration study costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,100,000 |  |  |  |
Total adjustment |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 7,800,000 | 7,800,000 |  |  |  |
Stipulated return on common equity percentage |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.00% |  |  |  |  |
Return on common equity percentage approved by PUC |  |  |  |  |  |  |  |  |  |  |  |  |  | 9.00% |  |  |  |  |
Return on common equity percentage approved by PUC allocated to lower interest rate |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.50% |  |  |  |  |
Return on common equity percentage approved by PUC allocated for OverCurtailment of renewable energy |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.50% |  |  |  |  |
Period as basis for calculation of average pension cost |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |
Charge recorded net of revenue taxes |  |  |  |  |  |  |  |  |  |  |  | $ 7,600,000 |  |  |  |  |  |  |
Amount to be refunded to customers |  |  |  |  |  |  |  |  |  |  | $ 9,700,000 |  |  |  |  |  |  |  |
Increase (decrease) in employee benefit expenses |  |  |  |  |  |  |  |  |  |  |  | (1,800,000) |  |  |  |  |  |  |
Deferred IRP cost allowed by PUC order, reclassified to deferred accounts |  |  |  |  |  |  |  |  |  |  |  | $ 700,000 |  |  |  |  |  |  |
General Rate Case Cycle Period | 3 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated increase in revenue, if base rate increased |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 11,600,000 |  |  |  |  |
Estimated increase in revenue, if base rate increased, percentage |  |  |  |  |  |  |  |  |  |  |  |  |  | 2.80% |  |  |  |  |
Estimated cost of common equity, percentage |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.75% |  |  |  |  |
Hawaiian Electric Company, Inc. and Subsidiaries |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fuel contracts |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated cost of minimum purchase within 2015 year |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 400,000,000 |  |  |  |  |
Estimated cost of minimum purchase in 2016 year |  |  |  |  |  |  |  |  |  |  |  |  |  | 300,000,000 |  |  |  |  |
Estimated cost of minimum purchase in 2017 year |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,400,000 |  |  |  |  |
Cost of purchases |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,100,000,000 | 1,100,000,000 | 1,300,000,000 |  |  |
Power purchase agreements |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Power purchase capacity excluding agreements with smaller IPPs (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  |  |  | 575 |  |  |  |  |
Purchased power |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 722,008,000 | $ 710,681,000 | 724,240,000 |  |  |
Expected fixed capacity charges per year for 2015 through 2019, minimum |  |  |  |  |  |  |  |  |  |  |  |  |  | 100,000,000 |  |  |  |  |
Expected fixed capacity charges from 2019 through 2033 |  |  |  |  |  |  |  |  |  |  |  |  |  | 500,000,000 |  |  |  |  |
Renewable projects |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of renewable portfolio standard to be achieved by 2030 |  |  |  |  |  |  |  |  |  | 40.00% |  |  |  |  |  |  |  |  |
Recovery of annual deferred costs contingent on approval |  |  |  |  | $ 405,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Integration from renewable energy sources (in megawatts) | MW |  |  | 200 |  |  |  |  |  |  |  |  |  |  |  | 200 |  |  |  |
Maximum deferred cost recovery |  |  |  |  |  |  |  |  | $ 5,890,000 |  |  |  |  |  |  |  |  |  |
Integration from firm renewable geothermal dispatchable energy (in megawatts) | MW |  |  |  |  |  |  | 50 |  |  |  |  |  |  |  |  |  |  |  |
Number of bids received | bid |  |  |  |  |  | 6 |  |  |  |  |  |  |  |  |  |  |  |  |
Environmental regulation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of reduction in GHG emissions by 2020 |  | 16.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated annual fee, emissions regulation |  |  |  |  |  |  |  |  |  |  |  |  |  | 500,000 |  |  |  |  |
D&O |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,987,323,000 | $ 2,980,172,000 | 3,109,439,000 |  |  |
Changes in the asset retirement obligation liability |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance at the beginning of the period |  |  |  |  |  |  |  |  |  |  |  |  |  | 43,106,000 | 48,431,000 |  |  |  |
Accretion expense |  |  |  |  |  |  |  |  |  |  |  |  |  | 890,000 | 1,263,000 |  |  |  |
Liabilities incurred |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 | 0 |  |  |  |
Liabilities settled |  |  |  |  |  |  |  |  |  |  |  |  |  | (14,577,000) | (5,672,000) |  |  |  |
Revisions in estimated cash flows |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 | (916,000) |  |  |  |
Balance at the end of the period |  |  |  |  |  |  |  |  |  |  |  |  |  | 29,419,000 | $ 43,106,000 | $ 48,431,000 |  |  |
Decoupling |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, baseline capital project value to determine revenue adjustment |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,500,000 |  |  |  |  |
Public Utilities, proposed rate base adjustment, percent of previous rate base adjustment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 90.00% |
Public Utilites, effective interest rate, revenue balancing account |  |  |  |  |  |  |  |  |  |  |  |  |  | 6.00% |  |  |  |  |
Hawaiian Electric Company, Inc. and Subsidiaries | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Decoupling |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, proposed effective interest rate, revenue balancing account |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.25% |
Hawaiian Electric Company, Inc. and Subsidiaries | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Decoupling |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, proposed effective interest rate, revenue balancing account |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.25% |
East Oahu Transmission Project Phase 1 | Hawaiian Electric Company, Inc. and Subsidiaries |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Renewable projects |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gross plant cost agreed to be written-off in lieu of regulatory audit |  |  |  |  |  |  |  | 9,500,000 |  |  |  |  |  |  |  |  |  |  |
After-tax charge to net income due to settlement agreement |  |  |  |  |  |  |  |  |  |  |  |  | $ 6,000,000 |  |  |  |  |  |
Additional increase in test year rate case |  |  |  |  |  |  |  | $ 5,000,000 |  |  |  |  |  |  |  |  |  |  |
Reserve for environmental costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Environmental regulation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reserve for additional investigation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 800,000 |  |

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- Definition The minimum estimated amount in the second year after the balance sheet date the entity agreed to spend under the long-term purchase commitment. + References No definition available. + Details
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- Definition The minimum estimated amount in the third year after the balance sheet date the entity agreed to spend under the long-term purchase commitment. + References No definition available. + Details
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- Definition The minimum estimated amount in the first year after the balance sheet date the entity agreed to spend under the long-term purchase commitment. + References No definition available. + Details
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- Definition Public Utilities, Proposed Effective Interest Rate, Revenue Balancing Account + References No definition available. + Details
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- Definition Public Utilities, Proposed Rate Base Adjustment, Percent of Previous Rate Base Adjustment + References No definition available. + Details
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- Definition Renewable Projects [Abstract] + References No definition available. + Details
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- Definition Represents the amount of additional accrued investigation and estimated cleanup costs. + References No definition available. + Details
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- Definition Represents the final approved ROACE percentage. + References No definition available. + Details
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- Definition Represents the final approved ROACE percentage allocated for over curtailment of renewable energy. + References No definition available. + Details
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- Definition Represents the final approved ROACE percentage allocated to lower interest rates. + References No definition available. + Details
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- Definition Represents the study costs. + References No definition available. + Details
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- Definition Represents the total amount of expected fixed capacity charges in the period for years six through twenty years. + References No definition available. + Details
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- Definition Represents the deferred cost of the wind project to be recovered by the entity per year according to the PUC approval. + References No definition available. + Details
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- Definition Represents the minimum amount of expected fixed capacity charges per year for years one through five. + References No definition available. + Details
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- Definition The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Asset Retirement Obligation -URI http://asc.fasb.org/extlink&oid=6505190 + Details
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- Definition Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6392676&loc=d3e7480-110848 + Details
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- Definition Amount of asset retirement obligations incurred during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Amount of the Increase or Decrease in the amount of the asset retirement obligation during the current period for changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(4) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- References No definition available. + Details
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- Definition The amount of regulated power revenues recognized during the period. + References No definition available. + Details
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- Definition Amount of operating expense for purchased power of regulated operation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(b)) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 + Details
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- Definition Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 09 -Article 12 + Details
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