Bank segment (HEI only) - Statements of Comprehensive Income - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net unrealized gains (losses) on securities arising during the period, taxes	$ (3,763)	$ (1,541)	$ 3,856
Less: reclassification adjustment for net realized gains included in net income, taxes	238	0	1,132
Net gains (losses) arising during the period, tax benefits	27,703	(3,753)	149,364
Less: amortization of net loss, prior service gain and transition obligation included in net periodic benefit cost, tax benefits	9,267	14,344	7,245
American Savings Bank (ASB)
Net unrealized gains (losses) on securities arising during the period, taxes	(3,763)	(1,541)	3,856
Less: reclassification adjustment for net realized gains included in net income, taxes	238	0	1,132
Net gains (losses) arising during the period, tax benefits	0	59	(6,164)
Less: amortization of net loss, prior service gain and transition obligation included in net periodic benefit cost, tax benefits	$ (566)	$ (1,011)	$ (561)