Financing Activities - Credit Arrangements (Details) £ in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)	Mar. 31, 2018 GBP (£)	Jan. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 GBP (£)
UNITED KINGDOM
Line of Credit Facility [Line Items]
Capacity | £		£ 1,315
Borrowed | £		497			£ 448
Letters of Credit and Commercial Paper Issued | £		4			4
Unused Capacity	$ 1,100	816
UNITED KINGDOM | Uncommitted Credit Facilities [Member]
Line of Credit Facility [Line Items]
Capacity | £		130
Borrowed | £		0			0
Letters of Credit and Commercial Paper Issued | £		4			4
Unused Capacity | £		126
WPD PLC [Member] | UNITED KINGDOM | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Jan. 31, 2022
Capacity | £		210
Borrowed	$ 200	145		$ 200	148
Letters of Credit and Commercial Paper Issued | £		0			£ 0
Unused Capacity | £		£ 67
Interest rate on outstanding borrowing	2.47%	2.47%		2.17%	2.17%
Borrowings | £		£ 143
WPD PLC [Member] | UNITED KINGDOM | Index Linked Term Loan [Member]
Line of Credit Facility [Line Items]
Expiration Date	Dec. 31, 2018
Capacity | £		130
Borrowed	$ 179	130
Letters of Credit and Commercial Paper Issued | £		0
Unused Capacity | £		£ 0
Interest rate on outstanding borrowing	1.77%	1.77%
WPD South West [Member] | UNITED KINGDOM | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Jul. 31, 2021
Capacity | £		£ 245
Borrowed | £		0			£ 0
Letters of Credit and Commercial Paper Issued | £		0			0
Unused Capacity | £		245
WPD East Midlands [Member] | UNITED KINGDOM | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Jul. 31, 2021
Capacity | £		300
Borrowed	$ 216	157		$ 244	180
Letters of Credit and Commercial Paper Issued | £		0			£ 0
Unused Capacity | £		£ 143
Interest rate on outstanding borrowing	0.90%	0.90%		0.89%	0.89%
WPD West Midlands [Member] | UNITED KINGDOM | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Jul. 31, 2021
Capacity | £		£ 300
Borrowed	$ 89	65		$ 162	£ 120
Letters of Credit and Commercial Paper Issued | £		0			£ 0
Unused Capacity | £		£ 235
Interest rate on outstanding borrowing	0.90%	0.90%		0.89%	0.89%
PPL Capital Funding [Member] | UNITED STATES
Line of Credit Facility [Line Items]
Capacity	$ 1,350
Borrowed	0			$ 0
Letters of Credit and Commercial Paper Issued	369			248
Unused Capacity	$ 981
PPL Capital Funding [Member] | UNITED STATES | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Jan. 31, 2023
Capacity	$ 950
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	345			230
Unused Capacity	$ 605
PPL Capital Funding [Member] | UNITED STATES | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Nov. 30, 2018
Capacity	$ 300
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	0			0
Unused Capacity	$ 300
PPL Capital Funding [Member] | UNITED STATES | Bilateral Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Mar. 31, 2019
Capacity	$ 100
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	24			18
Unused Capacity	$ 76
PPL Electric [Member] | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Jan. 31, 2023
Capacity	$ 650
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	214			1
Unused Capacity	$ 436
LKE [Member] | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Oct. 31, 2018
Capacity	$ 75
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	0			0
Unused Capacity	75
LGE [Member]
Line of Credit Facility [Line Items]
Capacity	700
Borrowed	200			100
Letters of Credit and Commercial Paper Issued	137			199
Unused Capacity	$ 363
LGE [Member] | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Jan. 31, 2023
Capacity	$ 500
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	137			199
Unused Capacity	$ 363
LGE [Member] | Term Loan Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Oct. 31, 2019
Capacity	$ 200
Borrowed	200		$ 100	100
Letters of Credit and Commercial Paper Issued	0			0
Unused Capacity	0
KU [Member]
Line of Credit Facility [Line Items]
Capacity	598
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	276			243
Unused Capacity	$ 322
KU [Member] | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Jan. 31, 2023
Capacity	$ 400
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	78			45
Unused Capacity	$ 322
KU [Member] | Letter Of Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Oct. 31, 2020
Capacity	$ 198
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	198			198
Unused Capacity	$ 0
PPL Electric Utilities Corp [Member] | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Jan. 31, 2023
Capacity	$ 650
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	214			1
Unused Capacity	$ 436
LG And E And KU Energy LLC [Member] | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Oct. 31, 2018
Capacity	$ 75
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	0			0
Unused Capacity	75
LG And E And KU Energy LLC [Member] | LGE [Member]
Line of Credit Facility [Line Items]
Capacity	700
Borrowed	200			100
Letters of Credit and Commercial Paper Issued	137			199
Unused Capacity	$ 363
LG And E And KU Energy LLC [Member] | LGE [Member] | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Jan. 31, 2023
Capacity	$ 500
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	137			199
Unused Capacity	$ 363
LG And E And KU Energy LLC [Member] | LGE [Member] | Term Loan Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Oct. 31, 2019
Capacity	$ 200
Borrowed	200		100	100
Letters of Credit and Commercial Paper Issued	0			0
Unused Capacity	0
LG And E And KU Energy LLC [Member] | KU [Member]
Line of Credit Facility [Line Items]
Capacity	598
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	276			243
Unused Capacity	$ 322
LG And E And KU Energy LLC [Member] | KU [Member] | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Jan. 31, 2023
Capacity	$ 400
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	78			45
Unused Capacity	$ 322
LG And E And KU Energy LLC [Member] | KU [Member] | Letter Of Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Oct. 31, 2020
Capacity	$ 198
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	198			198
Unused Capacity	0
Louisville Gas And Electric Co [Member]
Line of Credit Facility [Line Items]
Capacity	700
Borrowed	200			100
Letters of Credit and Commercial Paper Issued	137			199
Unused Capacity	$ 363
Louisville Gas And Electric Co [Member] | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Jan. 31, 2023
Capacity	$ 500
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	137			199
Unused Capacity	$ 363
Louisville Gas And Electric Co [Member] | Term Loan Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Oct. 31, 2019
Capacity	$ 200
Borrowed	200		$ 100	100
Letters of Credit and Commercial Paper Issued	0			0
Unused Capacity	0
Kentucky Utilities Co [Member]
Line of Credit Facility [Line Items]
Capacity	598
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	276			243
Unused Capacity	$ 322
Kentucky Utilities Co [Member] | Syndicated Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Jan. 31, 2023
Capacity	$ 400
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	78			45
Unused Capacity	$ 322
Kentucky Utilities Co [Member] | Letter Of Credit Facility [Member]
Line of Credit Facility [Line Items]
Expiration Date	Oct. 31, 2020
Capacity	$ 198
Borrowed	0			0
Letters of Credit and Commercial Paper Issued	198			$ 198
Unused Capacity	$ 0