Fair value measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2014
Financial assets
Available-for-sale investment securities, at fair value	$ 590,648	$ 550,394
Financial liabilities
Short-term borrowings—other than bank	30,500	118,972
Other bank borrowings	312,094	290,656
Carrying or notional amount
Financial assets
Money market funds	10	10
Available-for-sale investment securities, at fair value	590,648	550,394
Stock in Federal Home Loan Bank of Seattle	63,711	69,302
Loans receivable, net	4,411,410	4,397,457
Derivative assets	851	398
Financial liabilities
Deposit liabilities	4,751,328	4,623,415
Short-term borrowings—other than bank	30,500	118,972
Other bank borrowings	312,094	290,656
Long-term debt, net-other than bank	1,506,546	1,506,546
Derivative liabilities	281	114
Carrying or notional amount | American Savings Bank (ASB)
Financial liabilities
Notional amount of loans serviced	1,500,000	1,400,000
Estimated fair value
Financial assets
Money market funds	10	10
Available-for-sale investment securities, at fair value	590,648	550,394
Stock in Federal Home Loan Bank of Seattle	63,711	69,302
Loans receivable, net	4,616,814	4,578,822
Derivative assets	851	398
Financial liabilities
Deposit liabilities	4,752,331	4,623,773
Short-term borrowings—other than bank	30,500	118,972
Other bank borrowings	320,329	298,837
Long-term debt, net-other than bank	1,645,545	1,622,736
Derivative liabilities	281	114
Estimated fair value | Level 1
Financial assets
Derivative assets	0	0
Financial liabilities
Derivative liabilities	249	71
Estimated fair value | Level 2
Financial assets
Money market funds	10	10
Available-for-sale investment securities, at fair value	590,648	550,394
Stock in Federal Home Loan Bank of Seattle	63,711	69,302
Derivative assets	851	398
Financial liabilities
Deposit liabilities	4,752,331	4,623,773
Short-term borrowings—other than bank	30,500	118,972
Other bank borrowings	320,329	298,837
Long-term debt, net-other than bank	1,645,545	1,622,736
Derivative liabilities	32	43
Estimated fair value | Level 3
Financial assets
Loans receivable, net	4,616,814	4,578,822
Estimated fair value | American Savings Bank (ASB)
Financial liabilities
Servicing rights on loans	14,600	14,500
Hawaiian Electric Company | Carrying or notional amount
Financial liabilities
Short-term Debt, Fair Value	30,000
Long-term debt, net-other than bank	1,206,546	1,206,546
Hawaiian Electric Company | Estimated fair value
Financial liabilities
Short-term Debt, Fair Value	30,000
Long-term debt, net-other than bank	1,336,267	1,313,893
Hawaiian Electric Company | Estimated fair value | Level 2
Financial liabilities
Short-term Debt, Fair Value	30,000
Long-term debt, net-other than bank	$ 1,336,267	$ 1,313,893