Electric utility subsidiary - Consolidating statement of comprehensive income (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Condensed Statement of Income Captions [Line Items]
Net income for common stock	$ 31,866	$ 45,787
Retirement benefit plans:
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $3,141 and $1,605 for the respective periods	5,459	2,813
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,127 and $1,598 for the respective periods	(4,911)	(2,510)
Other comprehensive income, net of taxes	4,058	1,167
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	35,924	46,954
Hawaiian Electric Company
Condensed Statement of Income Captions [Line Items]
Net income for common stock	26,874	35,420
Retirement benefit plans:
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $3,141 and $1,605 for the respective periods	4,933	2,519
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,127 and $1,598 for the respective periods	(4,911)	(2,510)
Other comprehensive income, net of taxes	22	9
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	26,896	35,429
HELCO
Condensed Statement of Income Captions [Line Items]
Net income for common stock	3,788	5,161
Retirement benefit plans:
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $3,141 and $1,605 for the respective periods	651	344
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,127 and $1,598 for the respective periods	(651)	(344)
Other comprehensive income, net of taxes	0	0
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	3,788	5,161
Maui Electric
Condensed Statement of Income Captions [Line Items]
Net income for common stock	3,904	3,756
Retirement benefit plans:
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $3,141 and $1,605 for the respective periods	600	253
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,127 and $1,598 for the respective periods	(600)	(253)
Other comprehensive income, net of taxes	0	0
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	3,904	3,756
Other subsidiaries
Condensed Statement of Income Captions [Line Items]
Net income for common stock	0	0
Retirement benefit plans:
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $3,141 and $1,605 for the respective periods	0	0
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,127 and $1,598 for the respective periods	0	0
Other comprehensive income, net of taxes	0	0
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	0	0
Consolidating adjustments
Condensed Statement of Income Captions [Line Items]
Net income for common stock	(7,692)	(8,917)
Retirement benefit plans:
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $3,141 and $1,605 for the respective periods	(1,251)	(597)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,127 and $1,598 for the respective periods	1,251	597
Other comprehensive income, net of taxes	0	0
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	(7,692)	(8,917)
HECO Consolidated
Condensed Statement of Income Captions [Line Items]
Net income for common stock	26,874	35,420
Retirement benefit plans:
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $3,141 and $1,605 for the respective periods	4,933	2,519
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,127 and $1,598 for the respective periods	(4,911)	(2,510)
Other comprehensive income, net of taxes	22	9
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	$ 26,896	$ 35,429