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Electric utility segment - Power purchase agreements (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |
Purchased power | $ 161 | $ 153 | $ 301 | $ 280
Hawaiian Electric (parent only) | Kalaeloa Partners, L.P. (Kalaeloa) |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |
Purchased power | 52 | 48 | 92 | 88
Hawaiian Electric (parent only) | AES Hawaii |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |
Purchased power | 32 | 35 | 69 | 64
Hawaiian Electric (parent only) | HPOWER |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |
Purchased power | 17 | 16 | 32 | 33
Hawaiian Electric (parent only) | Puna Geothermal Venture |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |
Purchased power | 4 | 10 | 15 | 18
Hawaiian Electric (parent only) | Hamakua Energy Partners, L.P. (HEP) |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |
Purchased power | 15 | 10 | 22 | 17
Hawaiian Electric (parent only) | Other IPPs |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |
Purchased power | $ 41 | $ 34 | $ 71 | $ 60

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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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