Income taxes	9 Months Ended
Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income taxes	Income taxes The Company’s ETRs (combined federal and state income tax rates) for the third quarters of 2017 and 2016 were 36% and 29%, respectively, and for the first nine months of 2017 and 2016 were 35% and 32%, respectively. The ETR was higher for the three months and nine months ended September 30, 2017 compared to the same periods in 2016 due primarily to 2016 tax benefits recognized on previously nondeductible merger- and spin-off-related expenses and higher tax benefits recognized for the Domestic Production Activities Deduction (DPAD) in 2016 related to the Utilities’ generation activities when the Utilities were in a consolidated net operating loss position. Hawaiian Electric’s ETRs for the third quarters of 2017 and 2016 were 36% and 37%, respectively, and for the first nine months of 2017 and 2016 were 36% and 37%, respectively. The lower ETR was due in part to the tax benefits recognized for the DPAD as a result of moving out of a federal net operating loss position in 2017. Recent tax developments. The extension of bonus depreciation under the “Protecting Americans from Tax Hikes (PATH) Act of 2015” continues to be the most significant recent tax change. The PATH Act provides 50% bonus depreciation through 2017, phases down the percentage to 40% in 2018 and 30% in 2019 and then terminates bonus depreciation thereafter. Tax depreciation is expected to increase by approximately $120 million in 2017 due to bonus depreciation, which has the effect of increasing accumulated deferred tax liabilities. However, the rate of growth of accumulated deferred tax liabilities is decreasing over time as book depreciation “catches up” with the tax depreciation taken in the past.

Income taxes

9 Months Ended

Sep. 30, 2017

The Company’s ETRs (combined federal and state income tax rates) for the third quarters of 2017 and 2016 were 36% and 29%, respectively, and for the first nine months of 2017 and 2016 were 35% and 32%, respectively. The ETR was higher for the three months and nine months ended September 30, 2017 compared to the same periods in 2016 due primarily to 2016 tax benefits recognized on previously nondeductible merger- and spin-off-related expenses and higher tax benefits recognized for the Domestic Production Activities Deduction (DPAD) in 2016 related to the Utilities’ generation activities when the Utilities were in a consolidated net operating loss position.

Hawaiian Electric’s ETRs for the third quarters of 2017 and 2016 were 36% and 37%, respectively, and for the first nine months of 2017 and 2016 were 36% and 37%, respectively. The lower ETR was due in part to the tax benefits recognized for the DPAD as a result of moving out of a federal net operating loss position in 2017.

Recent tax developments. The extension of bonus depreciation under the “Protecting Americans from Tax Hikes (PATH) Act of 2015” continues to be the most significant recent tax change. The PATH Act provides 50% bonus depreciation through 2017, phases down the percentage to 40% in 2018 and 30% in 2019 and then terminates bonus depreciation thereafter. Tax depreciation is expected to increase by approximately $120 million in 2017 due to bonus depreciation, which has the effect of increasing accumulated deferred tax liabilities. However, the rate of growth of accumulated deferred tax liabilities is decreasing over time as book depreciation “catches up” with the tax depreciation taken in the past.