Organization and Basis of Presentation - Organization (Details) customer in Millions	9 Months Ended
	Sep. 30, 2018 customer subsidiary Rate MW
Summary Of Accounting Policies [Line Items]
Owned generating capacity | MW	12,300
Number of customers served | customer	1.6
Kansas Gas And Electric Company [Member] | Westar Energy Inc [Member]
Summary Of Accounting Policies [Line Items]
Number of active wholly owned subsidiaries | subsidiary	1
KCP&L Receivables Company [Member] | KCPL [Member]
Summary Of Accounting Policies [Line Items]
Number of active wholly owned subsidiaries | subsidiary	1
GMO Receivables Company [Member] | KCPL Greater Missouri Operations [Member]
Summary Of Accounting Policies [Line Items]
Number of active wholly owned subsidiaries | subsidiary	1
Transource Energy, LLC [Member] | GPE Transmission Holding Company, LLC [Member]
Summary Of Accounting Policies [Line Items]
Ownership percentage | Rate	13.50%
Transource Energy, LLC [Member] | AEP Transmission Holding Company, LLC [Member]
Summary Of Accounting Policies [Line Items]
Ownership interest | Rate	86.50%
Prairie Wind Transmission, LLC [Member] | Westar Energy Inc [Member]
Summary Of Accounting Policies [Line Items]
Ownership percentage | Rate	50.00%