XML 52 R38.htm IDEA: XBRL DOCUMENT v3.19.1
Electric utility segment - Commitments and contingencies (Details)
 1 Months Ended 3 Months Ended 12 Months Ended 33 Months Ended
Mar. 18, 2019
USD ($)
Aug. 11, 2016
USD ($)
Jun. 30, 2017
USD ($)
$ / kWh
MW
Jun. 30, 2015
MW
May 31, 2012
MW
Mar. 31, 1988
MW
Mar. 31, 2019
USD ($)
Dec. 31, 1988
MW
Mar. 31, 2019
USD ($)
Feb. 28, 2019
USD ($)
Regulatory Projects and Legal Obligations [Line Items]                    
Revenue subject to refund             $ 17,000,000      
Refunded amount $ 500,000                  
Public utility, ERP/EAM required pass through savings to customers   $ 244,000,000                
ERP/EAM project service period (in years)   12 years                
AFUDC rate   1.75%                
Project costs, accrued carrying costs once put into service             58,700,000   $ 58,700,000  
ERP/EAM implementation project, future operation and maintenance expense reductions                   $ 141,000,000
ERP/EAM implementation project, future cost avoidance related to capital and tax cost                   $ 103,000,000
West Lock PV Project, energy generated (in megawatts) | MW     20              
West Lock PV Project, cost cap     $ 67,000,000              
West Lock PV Project, maximum energy cost (in dollars per kilowatt hours) | $ / kWh     0.0956              
West Lock PV Project, project costs incurred                 44,200,000  
PCB Contamination                    
Environmental regulation                    
Valuation allowances and reserves             4,700,000   4,700,000  
AES Hawaii                    
Regulatory Projects and Legal Obligations [Line Items]                    
Purchase commitment, period (in years)           30 years        
Minimum power volume required (in megawatts) | MW           180        
Additional capacity requirement (in megawatts) | MW       9            
Hu Honua Bioenergy, LLC                    
Regulatory Projects and Legal Obligations [Line Items]                    
Minimum power volume required (in megawatts) | MW         21.5          
Maui Electric                    
Environmental regulation                    
Additional accrued investigation and estimated cleanup costs             $ 2,700,000   $ 2,700,000  
Kalaeloa Partners, L.P. (Kalaeloa) | Hawaiian Electric (parent only)                    
Regulatory Projects and Legal Obligations [Line Items]                    
Increased power purchase commitment capacity (in megawatts) | MW               208