Fair Value Measurements - Assets and Liabilities Measured on Recurring Basis Table (Details) - Recurring Fair Value Measurements [Member] - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 629	$ 485
Restricted cash and cash equivalents	24	26
Price risk management assets:
Foreign currency contracts	97	163
Cross-currency swaps	79	101
Total price risk management assets	176	264
Total assets	829	775
Price risk management liabilities:
Interest rate swaps	22	26
Foreign currency contracts	167	148
Total price risk management liabilities	189	174
Level 1 [Member]
Assets
Cash and cash equivalents	629	485
Restricted cash and cash equivalents	24	26
Price risk management assets:
Foreign currency contracts	0	0
Cross-currency swaps	0	0
Total price risk management assets	0	0
Total assets	653	511
Price risk management liabilities:
Interest rate swaps	0	0
Foreign currency contracts	0	0
Total price risk management liabilities	0	0
Level 2 [Member]
Assets
Cash and cash equivalents	0	0
Restricted cash and cash equivalents	0	0
Price risk management assets:
Foreign currency contracts	97	163
Cross-currency swaps	79	101
Total price risk management assets	176	264
Total assets	176	264
Price risk management liabilities:
Interest rate swaps	22	26
Foreign currency contracts	167	148
Total price risk management liabilities	189	174
Level 3 [Member]
Assets
Cash and cash equivalents	0	0
Restricted cash and cash equivalents	0	0
Price risk management assets:
Foreign currency contracts	0	0
Cross-currency swaps	0	0
Total price risk management assets	0	0
Total assets	0	0
Price risk management liabilities:
Interest rate swaps	0	0
Foreign currency contracts	0	0
Total price risk management liabilities	0	0
PPL Electric Utilities Corp [Member]
Assets
Cash and cash equivalents	20	49
Restricted cash and cash equivalents	2	2
Price risk management assets:
Total assets	22	51
PPL Electric Utilities Corp [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	20	49
Restricted cash and cash equivalents	2	2
Price risk management assets:
Total assets	22	51
PPL Electric Utilities Corp [Member] | Level 2 [Member]
Assets
Cash and cash equivalents	0	0
Restricted cash and cash equivalents	0	0
Price risk management assets:
Total assets	0	0
PPL Electric Utilities Corp [Member] | Level 3 [Member]
Assets
Cash and cash equivalents	0	0
Restricted cash and cash equivalents	0	0
Price risk management assets:
Total assets	0	0
LG And E And KU Energy LLC [Member]
Assets
Cash and cash equivalents	27	30
Price risk management assets:
Total assets	27	30
Price risk management liabilities:
Interest rate swaps	22	26
Total price risk management liabilities	22	26
LG And E And KU Energy LLC [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	27	30
Price risk management assets:
Total assets	27	30
Price risk management liabilities:
Interest rate swaps	0	0
Total price risk management liabilities	0	0
LG And E And KU Energy LLC [Member] | Level 2 [Member]
Assets
Cash and cash equivalents	0	0
Price risk management assets:
Total assets	0	0
Price risk management liabilities:
Interest rate swaps	22	26
Total price risk management liabilities	22	26
LG And E And KU Energy LLC [Member] | Level 3 [Member]
Assets
Cash and cash equivalents	0	0
Price risk management assets:
Total assets	0	0
Price risk management liabilities:
Interest rate swaps	0	0
Total price risk management liabilities	0	0
Louisville Gas And Electric Co [Member]
Assets
Cash and cash equivalents	14	15
Price risk management assets:
Total assets	14	15
Price risk management liabilities:
Interest rate swaps	22	26
Total price risk management liabilities	22	26
Louisville Gas And Electric Co [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	14	15
Price risk management assets:
Total assets	14	15
Price risk management liabilities:
Interest rate swaps	0	0
Total price risk management liabilities	0	0
Louisville Gas And Electric Co [Member] | Level 2 [Member]
Assets
Cash and cash equivalents	0	0
Price risk management assets:
Total assets	0	0
Price risk management liabilities:
Interest rate swaps	22	26
Total price risk management liabilities	22	26
Louisville Gas And Electric Co [Member] | Level 3 [Member]
Assets
Cash and cash equivalents	0	0
Price risk management assets:
Total assets	0	0
Price risk management liabilities:
Interest rate swaps	0	0
Total price risk management liabilities	0	0
Kentucky Utilities Co [Member]
Assets
Cash and cash equivalents	11	15
Price risk management assets:
Total assets	11	15
Kentucky Utilities Co [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	11	15
Price risk management assets:
Total assets	11	15
Kentucky Utilities Co [Member] | Level 2 [Member]
Assets
Cash and cash equivalents	0	0
Price risk management assets:
Total assets	0	0
Kentucky Utilities Co [Member] | Level 3 [Member]
Assets
Cash and cash equivalents	0	0
Price risk management assets:
Total assets	$ 0	$ 0