Summary of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Cash, Cash Equivalents and Restricted Cash from the Balance Sheet to Cash Flow Statement [Line Items]
Cash and cash equivalents	$ 629		$ 485
Restricted Cash, Current	3		3
Restricted Cash, Noncurrent	21		23
Cash, Cash Equivalents and Restricted Cash	653	$ 433	511	$ 367
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
Defined Benefit Plan Net Periodic Benefit (Cost) Credit Non Service, After tax	$ 4
Defined Benefit Plan Net Periodic Benefit (Cost) Credit NonService, Per Share	$ 0.01
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	$ 68	38
PPL Electric Utilities Corp [Member]
Reconciliation of Cash, Cash Equivalents and Restricted Cash from the Balance Sheet to Cash Flow Statement [Line Items]
Cash and cash equivalents	20		49
Restricted Cash, Current	2		2
Restricted Cash, Noncurrent	0		0
Cash, Cash Equivalents and Restricted Cash	22	22	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	2	(1)
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	27	15	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	2	(2)
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	14	4	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	1	(2)
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	11	7	$ 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	$ 1	$ (1)