SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Valuation and qualifying accounts
Reclassifications of allowance from one customer account into long term assets	$ (4,934)	$ 841	$ 1,790
Allowance for uncollectible accounts – electric utility | Hawaiian Electric Company, Inc. and Subsidiaries
Valuation and qualifying accounts
Balance at beginning of period	1,178	1,121	1,699
Charged to costs and expenses	2,474	1,810	2,383
Charged to other accounts	(4,099)	785	877
Deductions	(1,927)	2,538	3,838
Balance at end of period	1,480	1,178	1,121
Allowance for uncollectible interest – bank | Bank
Valuation and qualifying accounts
Balance at beginning of period	367	1,834	1,679
Charged to costs and expenses	0	0	0
Charged to other accounts	6	0	155
Deductions	0	1,467	0
Balance at end of period	373	367	1,834
Allowance for losses for loans – bank | Bank
Valuation and qualifying accounts
Balance at beginning of period	53,637	55,533	50,038
Charged to costs and expenses	14,745	10,901	16,763
Charged to other accounts	4,254	4,016	2,977
Deductions	20,517	16,813	14,245
Balance at end of period	52,119	53,637	55,533
Deferred tax valuation allowance – HEI
Valuation and qualifying accounts
Balance at beginning of period	$ 0	38	54
Charged to costs and expenses		0	0
Charged to other accounts		0	0
Deductions		38	16
Balance at end of period		$ 0	$ 38