Document Type Document Type Golden State Water Company Golden State Water Company [Member] Golden State Water Company [Member] Amendment Flag Amendment Flag City Area Code City Area Code Legal Entity [Axis] Legal Entity [Axis] Entity Address, State or Province Entity Address, State or Province Soliciting Material Soliciting Material Document Period End Date Document Period End Date Entity Tax Identification Number Entity Tax Identification Number Pre-commencement Tender Offer Pre-commencement Tender Offer Entities [Table] Entities [Table] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity File Number Entity File Number Entity Central Index Key Entity Central Index Key Trading Symbol Trading Symbol Entity Address, Postal Zip Code Entity Address, Postal Zip Code Local Phone Number Local Phone Number Written Communications Written Communications Title of 12(b) Security Title of 12(b) Security Security Exchange Name Security Exchange Name Entity [Domain] Entity [Domain] Entity Address, City or Town Entity Address, City or Town Cover [Abstract] Cover [Abstract] Pre-commencement Issuer Tender Offer Pre-commencement Issuer Tender Offer Entity Address, Address Line One Entity Address, Address Line One Entity Emerging Growth Company Entity Emerging Growth Company Entity Registrant Name Entity Registrant Name Entity Information [Line Items] Entity Information [Line Items]