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Retirement benefits (Details) (USD $) | 6 Months Ended |  |  | 6 Months Ended |  | 6 Months Ended |  | 3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended
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Jun. 30, 2012 | Jun. 30, 2011 | Dec. 31, 2011 | Apr. 02, 2011 | Jun. 30, 2012 Hawaiian Electric Industries, Inc. | Jun. 30, 2011 Hawaiian Electric Industries, Inc. | Dec. 31, 2011 Hawaiian Electric Industries, Inc. | Jun. 30, 2012 Electric utility | Jun. 30, 2011 Electric utility | Dec. 31, 2011 Electric utility | Jun. 30, 2012 Pension benefits Hawaiian Electric Industries, Inc. | Jun. 30, 2011 Pension benefits Hawaiian Electric Industries, Inc. | Jun. 30, 2012 Pension benefits Hawaiian Electric Industries, Inc. | Jun. 30, 2011 Pension benefits Hawaiian Electric Industries, Inc. | Jun. 30, 2012 Other benefits Hawaiian Electric Industries, Inc. | Jun. 30, 2011 Other benefits Hawaiian Electric Industries, Inc. | Jun. 30, 2012 Other benefits Hawaiian Electric Industries, Inc. | Jun. 30, 2011 Other benefits Hawaiian Electric Industries, Inc.
Defined benefit plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contributions made to defined benefit plans | $ 53,000,000 | $ 38,000,000 |  |  | $ 1,000,000 |  |  | $ 52,000,000 | $ 38,000,000 |  |  |  |  |  |  |  |  |
Current estimate of contributions to defined benefit plans in current fiscal year | 107,000,000 |  | 75,000,000 |  | 3,000,000 |  | 2,000,000 | 104,000,000 |  | 73,000,000 |  |  |  |  |  |  |  |
Benefits expected to be paid directly by the company in current fiscal year | 2,000,000 |  |  |  | 1,000,000 |  |  | 1,000,000 |  |  |  |  |  |  |  |  |  |
Service cost |  |  |  |  |  |  |  |  |  |  | 11,397,000 | 8,824,000 | 21,588,000 | 17,741,000 | 1,008,000 | 1,173,000 | 2,104,000 | 2,440,000
Interest cost |  |  |  |  |  |  |  |  |  |  | 16,973,000 | 16,271,000 | 33,744,000 | 32,580,000 | 2,223,000 | 2,417,000 | 4,504,000 | 4,878,000
Expected return on plan assets |  |  |  |  |  |  |  |  |  |  | (17,736,000) | (17,172,000) | (35,592,000) | (34,273,000) | (2,557,000) | (2,657,000) | (5,178,000) | (5,305,000)
Amortization of net transition obligation |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,000 |  |  |  |
Amortization of prior service gain |  |  |  |  |  |  |  |  |  |  | (82,000) | (97,000) | (163,000) | (194,000) | (449,000) | (309,000) | (897,000) | (533,000)
Amortization of net actuarial loss |  |  |  |  |  |  |  |  |  |  | 6,403,000 | 4,314,000 | 12,826,000 | 8,719,000 | 299,000 | 40,000 | 752,000 | 55,000
Net periodic benefit cost |  |  |  |  |  |  |  |  |  |  | 16,955,000 | 12,140,000 | 32,403,000 | 24,574,000 | 524,000 | 664,000 | 1,285,000 | 1,535,000
Impact of PUC D&Os |  |  |  |  |  |  |  |  |  |  | (4,977,000) | (556,000) | (8,834,000) | (2,100,000) | (416,000) | 1,734,000 | (1,096,000) | 2,752,000
Net periodic benefit cost (adjusted for impact of PUC D&Os) |  |  |  |  |  |  |  |  |  |  | 11,978,000 | 11,584,000 | 23,569,000 | 22,474,000 | 108,000 | 2,398,000 | 189,000 | 4,287,000
Amount available as single sum distribution option under accelerated distribution options |  |  |  | 50,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Funded status of retirement plan (as a percent) |  |  |  | 80.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of participant's total benefit that may be elected while partial restrictions are in effect |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retirement benefits expense |  |  |  |  | 17,000,000 | 20,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Defined contribution plan, expenses recognized | 1,800,000 | 1,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash contributions by the employer to defined contribution plan | $ 2,700,000 | $ 2,800,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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- Definition The employer's best estimate of contributions expected to be paid to the plan in the current fiscal period. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions. + References No definition available. + Details
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- Definition Represents the total amount of net periodic benefit cost adjusted for impact of Public Utilities Commission's decisions and orders. + References No definition available. + Details
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- Definition The amount of gains or losses recognized in net periodic benefit cost. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(4) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 + Details
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- Definition The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 + Details
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- Definition An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(3) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Expected Return on Plan Assets -URI http://asc.fasb.org/extlink&oid=6512136 -Topic 715 -SubTopic 30 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Expected Return on Plan Assets -URI http://asc.fasb.org/extlink&oid=6512171 -Topic 715 -SubTopic 60 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 106 -Paragraph 518 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 264 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 106 -Paragraph 518 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 264 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a, h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 + Details
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- Definition The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 106 -Paragraph 518 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Service Cost (Component of Net Periodic Pension Cost) -URI http://asc.fasb.org/extlink&oid=6525008 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 264 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a, h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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