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Electric utility segment - Power purchase agreements (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |
Purchased power | $ 177 | $ 161 | $ 478 | $ 441
Hawaiian Electric (parent only) | Kalaeloa Partners, L.P. (Kalaeloa) |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |
Purchased power | 62 | 48 | 154 | 136
Hawaiian Electric (parent only) | AES Hawaii |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |
Purchased power | 38 | 39 | 107 | 103
Hawaiian Electric (parent only) | HPOWER |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |
Purchased power | 19 | 18 | 51 | 51
Hawaiian Electric (parent only) | Puna Geothermal Venture |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |
Purchased power | 0 | 10 | 15 | 28
Hawaiian Electric (parent only) | Hamakua Energy Partners, L.P. (HEP) |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |
Purchased power | 17 | 8 | 39 | 25
Hawaiian Electric (parent only) | Other IPPs |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |
Purchased power | $ 41 | $ 38 | $ 112 | $ 98

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- Definition Amount of operating expense for purchased power of regulated operation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(b)) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
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