Income taxes Deferred Tax Assets and Liabilities Due to Book/Tax Differences (Details) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets
Net operating loss	$ 0	$ 0
Other	58,352	57,239
Total deferred tax assets	58,352	57,239
Deferred tax liabilities
Property, plant and equipment	448,723	378,280
Repairs deduction	86,408	75,127
Regulatory assets, excluding amounts attributable to property, plant and equipment	33,795	33,251
Deferred RAM and RBA revenues	32,889	0
Retirement benefits	25,336	29,280
Other	62,935	70,561
Total deferred tax liabilities	690,086	586,499
Deferred income taxes (credit)	631,734	529,260
Total deferred tax liabilities	631,734	529,260
Prepayments and other (Current assets-debit)
Deferred tax liabilities
Total deferred tax liabilities	0	0
Other (Current liabilities-credit)
Deferred tax liabilities
Total deferred tax liabilities	0	0
Hawaiian Electric Company, Inc. and Subsidiaries
Deferred tax assets
Net operating loss	51,936	19,848
Other	17,663	17,295
Total deferred tax assets	69,599	37,143
Deferred tax liabilities
Property, plant and equipment	446,259	375,771
Repairs deduction	86,408	75,127
Regulatory assets, excluding amounts attributable to property, plant and equipment	33,795	33,251
Deferred RAM and RBA revenues	32,889
Retirement benefits	28,758	23,851
Other	14,929	15,602
Total deferred tax liabilities	643,038	523,602
Deferred income taxes (credit)	602,872	507,161
Total deferred tax liabilities	573,439	486,459
Hawaiian Electric Company, Inc. and Subsidiaries | Prepayments and other (Current assets-debit)
Deferred tax liabilities
Total deferred tax liabilities	(32,915)	(20,702)
Hawaiian Electric Company, Inc. and Subsidiaries | Other (Current liabilities-credit)
Deferred tax liabilities
Total deferred tax liabilities	$ 3,482	$ 0