Shareholders' equity - Reclassification Out Of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on securities	$ (617,395)	$ (646,055)	$ (566,244)	$ (550,960)	$ (624,032)	$ (717,176)	$ (623,912)	$ (637,862)	$ (2,380,654)	$ (2,602,982)	$ (3,239,542)
Interest rate contracts (settled in 2011)									75,803	77,150	76,352
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost									(14,518)	(22,465)	(11,344)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets									(28,584)	25,139	(207,833)
Hawaiian Electric Company, Inc. and Subsidiaries
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on securities	$ (544,668)	$ (572,253)	$ (495,395)	$ (482,052)	$ (555,434)	$ (648,127)	$ (558,163)	$ (573,442)	(2,094,368)	(2,335,166)	(2,987,323)
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost									(13,254)	(20,381)	(10,212)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets									(28,584)	25,139	(207,833)
Bank
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on securities									(285,924)	(267,733)	(252,497)
Electric utility
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on securities									(2,094,368)	(2,335,166)	(2,987,323)
Amount reclassified from AOCI
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications									42,623	(2,439)	217,698
Amount reclassified from AOCI | Hawaiian Electric Company, Inc. and Subsidiaries
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications									41,665	(4,758)	218,045
Amount reclassified from AOCI | Net unrealized gains (losses) on securities | Bank
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on securities									(360)	0	(1,715)
Amount reclassified from AOCI | Unrealized gains(losses) on derivatives | Interest rate contracts
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Interest rate contracts (settled in 2011)									54	235	236
Amount reclassified from AOCI | Unrealized gains(losses) on derivatives | Electric utility | Window forward contracts
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on securities									(173)	0	0
Amount reclassified from AOCI | Unrealized gains(losses) on derivatives | Electric utility | Window forward contracts | Hawaiian Electric Company, Inc. and Subsidiaries
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on securities									(173)	0	0
Amount reclassified from AOCI | Retirement benefit plans
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost									14,518	22,465	11,344
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets									28,584	(25,139)	207,833
Amount reclassified from AOCI | Retirement benefit plans | Hawaiian Electric Company, Inc. and Subsidiaries
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost									13,254	20,381	10,212
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets									$ 28,584	$ (25,139)	$ 207,833