Bank segment (HEI only) - Carrying Amount of Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Recorded investment:
With no related allowance recorded	$ 14,072	$ 18,811
With an allowance recorded	19,321	32,948
Recorded investment	33,393	51,759
Unpaid principal balance:
With no related allowance recorded	16,041	23,200
With an allowance recorded	19,574	33,205
Unpaid principal balance	35,615	56,405
Related Allowance	2,730	4,083
Average recorded investment:
With no related allowance recorded	15,378	22,579	$ 19,651
With an allowance recorded	21,160	36,398	31,732
Average recorded investment	36,538	58,977	51,383
Interest income recognized:
With no related allowance recorded	599	783	704
With an allowance recorded	1,621	1,271	1,140
Interest income recognized	2,220	2,054	1,844
Residential 1-4 family
Recorded investment:
With no related allowance recorded	9,097	9,571
With an allowance recorded	9,187	10,283
Recorded investment	18,284	19,854
Unpaid principal balance:
With no related allowance recorded	9,644	10,400
With an allowance recorded	9,390	10,486
Unpaid principal balance	19,034	20,886
Related Allowance	1,248	1,352
Average recorded investment:
With no related allowance recorded	9,440	10,136	11,215
With an allowance recorded	9,818	11,589	11,578
Average recorded investment	19,258	21,725	22,793
Interest income recognized:
With no related allowance recorded	316	324	332
With an allowance recorded	493	457	562
Interest income recognized	809	781	894
Commercial real estate
Recorded investment:
With no related allowance recorded	0	223
With an allowance recorded	1,016	1,346
Recorded investment	1,016	1,569
Unpaid principal balance:
With no related allowance recorded	0	228
With an allowance recorded	1,016	1,346
Unpaid principal balance	1,016	1,574
Related Allowance	65	80
Average recorded investment:
With no related allowance recorded	91	1,124	370
With an allowance recorded	1,241	1,962	1,699
Average recorded investment	1,332	3,086	2,069
Interest income recognized:
With no related allowance recorded	11	0	74
With an allowance recorded	54	15	0
Interest income recognized	65	15	74
Home equity line of credit
Recorded investment:
With no related allowance recorded	1,496	1,500
With an allowance recorded	6,692	4,658
Recorded investment	8,188	6,158
Unpaid principal balance:
With no related allowance recorded	1,789	1,900
With an allowance recorded	6,736	4,712
Unpaid principal balance	8,525	6,612
Related Allowance	647	215
Average recorded investment:
With no related allowance recorded	1,976	1,105	484
With an allowance recorded	5,045	3,765	1,597
Average recorded investment	7,021	4,870	2,081
Interest income recognized:
With no related allowance recorded	101	23	4
With an allowance recorded	251	137	49
Interest income recognized	352	160	53
Residential land
Recorded investment:
With no related allowance recorded	1,143	1,218
With an allowance recorded	122	2,411
Recorded investment	1,265	3,629
Unpaid principal balance:
With no related allowance recorded	1,434	1,803
With an allowance recorded	122	2,411
Unpaid principal balance	1,556	4,214
Related Allowance	47	789
Average recorded investment:
With no related allowance recorded	1,094	1,518	2,397
With an allowance recorded	1,308	2,964	4,337
Average recorded investment	2,402	4,482	6,734
Interest income recognized:
With no related allowance recorded	117	66	137
With an allowance recorded	97	206	318
Interest income recognized	214	272	455
Commercial construction
Recorded investment:
With no related allowance recorded	0	0
With an allowance recorded	0	0
Recorded investment	0	0
Unpaid principal balance:
With no related allowance recorded	0	0
With an allowance recorded	0	0
Unpaid principal balance	0	0
Related Allowance	0	0
Average recorded investment:
With no related allowance recorded	0	0	0
With an allowance recorded	0	0	0
Average recorded investment	0	0	0
Interest income recognized:
With no related allowance recorded	0	0	0
With an allowance recorded	0	0	0
Interest income recognized	0	0	0
Residential construction
Recorded investment:
With no related allowance recorded	0	0
With an allowance recorded	0	0
Recorded investment	0	0
Unpaid principal balance:
With no related allowance recorded	0	0
With an allowance recorded	0	0
Unpaid principal balance	0	0
Related Allowance	0	0
Average recorded investment:
With no related allowance recorded	0	0	0
With an allowance recorded	0	0	0
Average recorded investment	0	0	0
Interest income recognized:
With no related allowance recorded	0	0	0
With an allowance recorded	0	0	0
Interest income recognized	0	0	0
Commercial
Recorded investment:
With no related allowance recorded	2,328	6,299
With an allowance recorded	2,246	14,240
Recorded investment	4,574	20,539
Unpaid principal balance:
With no related allowance recorded	3,166	8,869
With an allowance recorded	2,252	14,240
Unpaid principal balance	5,418	23,109
Related Allowance	694	1,641
Average recorded investment:
With no related allowance recorded	2,776	8,694	5,185
With an allowance recorded	3,691	16,106	12,507
Average recorded investment	6,467	24,800	17,692
Interest income recognized:
With no related allowance recorded	54	370	157
With an allowance recorded	723	456	211
Interest income recognized	777	826	368
Consumer
Recorded investment:
With no related allowance recorded	8	0
With an allowance recorded	58	10
Recorded investment	66	10
Unpaid principal balance:
With no related allowance recorded	8	0
With an allowance recorded	58	10
Unpaid principal balance	66	10
Related Allowance	29	6
Average recorded investment:
With no related allowance recorded	1	2	0
With an allowance recorded	57	12	14
Average recorded investment	58	14	14
Interest income recognized:
With no related allowance recorded	0	0	0
With an allowance recorded	3	0	0
Interest income recognized	$ 3	$ 0	$ 0