Summary of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Summary Of Significant Accounting Policies [Line Items]
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit- Non Service	$ 61	$ 41	$ 195	$ 123
Reconciliation of Cash, Cash Equivalents and Restricted Cash from the Balance Sheet to Cash Flow Statement [Line Items]
Cash and cash equivalents	842		842		$ 485
Restricted Cash, Current	3		3		3
Restricted Cash, Noncurrent	19		19		23
Cash, Cash Equivalents and Restricted Cash	864	696	864	696	511	$ 365
Income Statement impact of ASU 2017-07 [Member]
Summary Of Significant Accounting Policies [Line Items]
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit- Non Service	5		16
Defined Benefit Plan Net Periodic Benefit (Cost) Credit Non Service, After tax	$ 4		$ 13
Defined Benefit Plan Net Periodic Benefit (Cost) Credit NonService, Per Share	$ 0.01		$ 0.02
Impact of adoption of ASU 2017-07 [Member]
Summary Of Significant Accounting Policies [Line Items]
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit- Non Service	$ 61	41	$ 195	123
PPL Electric Utilities Corp [Member]
Summary Of Significant Accounting Policies [Line Items]
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit- Non Service	1	0	4	0
Reconciliation of Cash, Cash Equivalents and Restricted Cash from the Balance Sheet to Cash Flow Statement [Line Items]
Cash and cash equivalents	414		414		49
Restricted Cash, Current	2		2		2
Restricted Cash, Noncurrent	0		0		0
Cash, Cash Equivalents and Restricted Cash	416	245	416	245	51	15
PPL Electric Utilities Corp [Member] | Impact of adoption of ASU 2017-07 [Member]
Summary Of Significant Accounting Policies [Line Items]
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit- Non Service	1	0	4	0
LG And E And KU Energy LLC [Member]
Reconciliation of Cash, Cash Equivalents and Restricted Cash from the Balance Sheet to Cash Flow Statement [Line Items]
Cash and cash equivalents	29	40	29	40	30	13
LG And E And KU Energy LLC [Member] | Impact of adoption of ASU 2017-07 [Member]
Summary Of Significant Accounting Policies [Line Items]
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit- Non Service	1	(2)	3	(4)
Louisville Gas And Electric Co [Member]
Reconciliation of Cash, Cash Equivalents and Restricted Cash from the Balance Sheet to Cash Flow Statement [Line Items]
Cash and cash equivalents	11	9	11	9	15	5
Louisville Gas And Electric Co [Member] | Impact of adoption of ASU 2017-07 [Member]
Summary Of Significant Accounting Policies [Line Items]
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit- Non Service	0	(2)	(1)	(4)
Kentucky Utilities Co [Member]
Reconciliation of Cash, Cash Equivalents and Restricted Cash from the Balance Sheet to Cash Flow Statement [Line Items]
Cash and cash equivalents	18	31	18	31	$ 15	$ 7
Kentucky Utilities Co [Member] | Impact of adoption of ASU 2017-07 [Member]
Summary Of Significant Accounting Policies [Line Items]
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit- Non Service	$ 0	$ 0	$ 2	$ (1)