Retirement and Postemployment Benefits (Savings Plans and Employee Stock Ownership Plan) (Details) - Deferred Savings Plans 401K [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Contribution Pension And Other Postretirement Plans [Line Items]
Employer contributions to deferred savings plans	$ 36	$ 35	$ 34
PPL Electric Utilities Corp [Member]
Defined Contribution Pension And Other Postretirement Plans [Line Items]
Employer contributions to deferred savings plans	6	6	6
LG And E And KU Energy LLC [Member]
Defined Contribution Pension And Other Postretirement Plans [Line Items]
Employer contributions to deferred savings plans	18	17	16
Louisville Gas And Electric Co [Member]
Defined Contribution Pension And Other Postretirement Plans [Line Items]
Employer contributions to deferred savings plans	5	5	5
Kentucky Utilities Co [Member]
Defined Contribution Pension And Other Postretirement Plans [Line Items]
Employer contributions to deferred savings plans	$ 4	$ 4	$ 4