Basis of presentation (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, liability	$ 213,166
Operating lease right-of-use assets	213,910
Hawaiian Electric Company, Inc. and Subsidiaries
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, liability	192,000
Operating lease right-of-use assets	$ 192,254
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, liability		$ 257,000
Operating lease right-of-use assets		257,000
ASU 2016-02 | Power Purchase Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, liability		215,000
Operating lease right-of-use assets		215,000
ASU 2016-02 | Hawaiian Electric Company, Inc. and Subsidiaries
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, liability		236,000
Operating lease right-of-use assets		$ 236,000