Retirement and Postemployment Benefits (Net Period Defined Benefit Costs (Credits) and Other Changes in Plan Assets and Benefit Obligations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Plan [Member] | U.S. [Member]
Net Periodic Defined Benefit Costs (Credits): [ Abstract]
Service cost	$ 65	$ 66	$ 96
Interest cost	168	174	194
Expected return on plan assets	(231)	(228)	(258)
Amortization of:
Prior service cost (credit)	10	8	7
Actuarial (gain) loss	69	50	84
Net periodic defined benefit costs (credits) prior to settlements and termination benefits	81	70	123
Settlements	1	3	0
Termination benefits	1	0	0
Net periodic defined benefit costs (credits)	83	73	123
Other Changes in Plan Assets and Benefit Obligations Recognized in OCI and Regulatory Assets/Liabilities - Gross: [Abstract]
Divestiture	0	0	(353)
Settlement	(1)	(3)	0
Net (gain) loss	27	253	63
Prior service costs (credit)	(1)	15	18
Amortization of: [Abstract]
Prior service (cost) credit	(10)	(8)	(7)
Actuarial gain (loss)	(69)	(50)	(85)
Total recognized in OCI and regulatory assets/liabilities	(54)	207	(364)
Total recognized in net periodic benefit costs, OCI and regulatory assets/liabilities	29	280	(241)
Other Changes in Plan Assets and Benefit Obligations Recognized in OCI and Regulatory Assets/Liabilities - Gross (Details) [Abstract]
OCI	(53)	236	(269)
Regulatory assets/liabilities	(1)	(29)	(95)
Total recognized in OCI and regulatory assets/liabilities	(54)	207	(364)
Estimated Amounts to be Amortized From AOCI and Regulatory Assets into Net Periodic Benefit Costs in the Next Fiscal Period (Details) [Abstract]
Prior service cost (credit)	10
Actuarial (gain) loss	86
Total	96
Amortization from Balance Sheet: [Abstract]
AOCI	28
Regulatory assets/liabilities	68
Total	96
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Net periodic defined benefit costs (credits) charged to operating expense or regulatory assets, excluding amounts charged to construction and other non-expense accounts	59	53	71
Pension Plan [Member] | U.K. [Member]
Net Periodic Defined Benefit Costs (Credits): [ Abstract]
Service cost	76	69	79
Interest cost	178	235	314
Expected return on plan assets	(514)	(504)	(523)
Amortization of:
Prior service cost (credit)	0	0	0
Actuarial (gain) loss	144	138	158
Net periodic defined benefit costs (credits) prior to settlements and termination benefits	(116)	(62)	28
Settlements	0	0	0
Termination benefits	0	0	0
Net periodic defined benefit costs (credits)	(116)	(62)	28
Other Changes in Plan Assets and Benefit Obligations Recognized in OCI and Regulatory Assets/Liabilities - Gross: [Abstract]
Divestiture	0	0	0
Settlement	0	0	0
Net (gain) loss	346	7	508
Prior service costs (credit)	0	0	0
Amortization of: [Abstract]
Prior service (cost) credit	0	0	0
Actuarial gain (loss)	(144)	(138)	(158)
Total recognized in OCI and regulatory assets/liabilities	202	(131)	350
Total recognized in net periodic benefit costs, OCI and regulatory assets/liabilities	86	(193)	378
Other Changes in Plan Assets and Benefit Obligations Recognized in OCI and Regulatory Assets/Liabilities - Gross (Details) [Abstract]
Total recognized in OCI and regulatory assets/liabilities	202	(131)	350
Estimated Amounts to be Amortized From AOCI and Regulatory Assets into Net Periodic Benefit Costs in the Next Fiscal Period (Details) [Abstract]
Prior service cost (credit)	0
Actuarial (gain) loss	152
Total	152
Amortization from Balance Sheet: [Abstract]
AOCI	152
Regulatory assets/liabilities	0
Total	152
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Net periodic defined benefit costs (credits) charged to operating expense or regulatory assets, excluding amounts charged to construction and other non-expense accounts	(151)	(95)	(21)
Other Postretirement Benefits Plan [Member]
Net Periodic Defined Benefit Costs (Credits): [ Abstract]
Service cost	7	7	11
Interest cost	23	26	26
Expected return on plan assets	(22)	(22)	(26)
Amortization of:
Prior service cost (credit)	(1)	0	1
Actuarial (gain) loss	1	1	0
Net periodic defined benefit costs (credits) prior to settlements and termination benefits	8	12	12
Settlements	0	0	0
Termination benefits	0	0	0
Net periodic defined benefit costs (credits)	8	12	12
Other Changes in Plan Assets and Benefit Obligations Recognized in OCI and Regulatory Assets/Liabilities - Gross: [Abstract]
Divestiture	0	0	(6)
Settlement	0	0	0
Net (gain) loss	(28)	9	(9)
Prior service costs (credit)	8	0	0
Amortization of: [Abstract]
Prior service (cost) credit	1	(1)	(1)
Actuarial gain (loss)	(1)	(1)	0
Total recognized in OCI and regulatory assets/liabilities	(20)	7	(16)
Total recognized in net periodic benefit costs, OCI and regulatory assets/liabilities	(12)	19	(4)
Other Changes in Plan Assets and Benefit Obligations Recognized in OCI and Regulatory Assets/Liabilities - Gross (Details) [Abstract]
OCI	(25)	7	12
Regulatory assets/liabilities	5	0	(28)
Total recognized in OCI and regulatory assets/liabilities	(20)	7	(16)
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Net periodic defined benefit costs (credits) charged to operating expense or regulatory assets, excluding amounts charged to construction and other non-expense accounts	$ 5	7	8
PPL Electric Utilities Corp [Member]
Amortization of:
Amortization period for the deferred recovery of a regulatory asset	5 years
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Amortization period for the deferred recovery of a regulatory asset	5 years
PPL Electric Utilities Corp [Member] | Pension Plan [Member] | U.S. [Member]
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Net periodic defined benefit costs (credits) charged to operating expense or regulatory assets, excluding amounts charged to construction and other non-expense accounts	$ 12	10	15
PPL Electric Utilities Corp [Member] | Other Postretirement Benefits Plan [Member]
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Net periodic defined benefit costs (credits) charged to operating expense or regulatory assets, excluding amounts charged to construction and other non-expense accounts	0	1	0
LG And E And KU Energy LLC [Member] | Pension Plan [Member]
Amortization of:
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	11	6	9
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	(11)	(6)	(9)
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member]
Net Periodic Defined Benefit Costs (Credits): [ Abstract]
Service cost	24	23	26
Interest cost	68	71	68
Expected return on plan assets	(92)	(91)	(88)
Amortization of:
Prior service cost (credit)	8	8	7
Actuarial (gain) loss	31	21	37
Net periodic defined benefit costs (credits)	$ 39	$ 32	$ 50
Amortization period for the deferred recovery of a regulatory asset	15 years	15 years	15 years
Other Changes in Plan Assets and Benefit Obligations Recognized in OCI and Regulatory Assets/Liabilities - Gross: [Abstract]
Net (gain) loss	$ 30	$ 119	$ 20
Prior service costs (credit)	7	0	19
Amortization of: [Abstract]
Prior service (cost) credit	(8)	(8)	(7)
Actuarial gain (loss)	(32)	(21)	(37)
Total recognized in OCI and regulatory assets/liabilities	(3)	90	(5)
Total recognized in net periodic benefit costs, OCI and regulatory assets/liabilities	36	122	45
Other Changes in Plan Assets and Benefit Obligations Recognized in OCI and Regulatory Assets/Liabilities - Gross (Details) [Abstract]
OCI	33	42	4
Regulatory assets/liabilities	(36)	48	(9)
Total recognized in OCI and regulatory assets/liabilities	(3)	90	(5)
Estimated Amounts to be Amortized From AOCI and Regulatory Assets into Net Periodic Benefit Costs in the Next Fiscal Period (Details) [Abstract]
Prior service cost (credit)	9
Actuarial (gain) loss	39
Total	48
Amortization from Balance Sheet: [Abstract]
AOCI	11
Regulatory assets/liabilities	37
Total	48
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Net periodic defined benefit costs (credits) charged to operating expense or regulatory assets, excluding amounts charged to construction and other non-expense accounts	$ 28	$ 24	$ 37
Amortization period for the deferred recovery of a regulatory asset	15 years	15 years	15 years
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Qualified Plan [Member]
Amortization of:
Settlements	$ 5
LG And E And KU Energy LLC [Member] | Other Postretirement Benefits Plan [Member]
Net Periodic Defined Benefit Costs (Credits): [ Abstract]
Service cost	4	$ 5	$ 5
Interest cost	9	9	9
Expected return on plan assets	(7)	(6)	(6)
Amortization of:
Prior service cost (credit)	1	3	3
Actuarial (gain) loss	0	(1)	0
Net periodic defined benefit costs (credits)	$ 7	$ 10	$ 11
Amortization period for the deferred recovery of a regulatory asset	15 years	15 years	15 years
Other Changes in Plan Assets and Benefit Obligations Recognized in OCI and Regulatory Assets/Liabilities - Gross: [Abstract]
Net (gain) loss	$ (14)	$ 6	$ (15)
Prior service costs (credit)	8	0	0
Amortization of: [Abstract]
Prior service (cost) credit	(1)	(3)	(3)
Actuarial gain (loss)	0	1	0
Total recognized in OCI and regulatory assets/liabilities	(7)	4	(18)
Total recognized in net periodic benefit costs, OCI and regulatory assets/liabilities	0	14	(7)
Other Changes in Plan Assets and Benefit Obligations Recognized in OCI and Regulatory Assets/Liabilities - Gross (Details) [Abstract]
OCI	(2)	2	(2)
Regulatory assets/liabilities	(5)	2	(16)
Total recognized in OCI and regulatory assets/liabilities	(7)	4	(18)
Estimated Amounts to be Amortized From AOCI and Regulatory Assets into Net Periodic Benefit Costs in the Next Fiscal Period (Details) [Abstract]
Prior service cost (credit)	1
Actuarial (gain) loss	0
Total	1
Amortization from Balance Sheet: [Abstract]
AOCI	0
Regulatory assets/liabilities	1
Total	1
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Net periodic defined benefit costs (credits) charged to operating expense or regulatory assets, excluding amounts charged to construction and other non-expense accounts	$ 5	$ 6	$ 8
Amortization period for the deferred recovery of a regulatory asset	15 years	15 years	15 years
LG And E And KU Energy LLC [Member] | KU [Member] | Other Postretirement Benefits Plan [Member]
Amortization of:
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	$ (2)	$ (2)	$ (1)
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	2	2	1
LG And E And KU Energy LLC [Member] | LGE [Member] | Other Postretirement Benefits Plan [Member]
Amortization of:
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	(4)	(3)	(4)
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	4	3	4
Louisville Gas And Electric Co [Member] | Pension Plan [Member]
Amortization of:
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	7	5	3
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	(7)	(5)	(3)
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member]
Net Periodic Defined Benefit Costs (Credits): [ Abstract]
Service cost	1	1	1
Interest cost	13	15	14
Expected return on plan assets	(22)	(21)	(20)
Amortization of:
Prior service cost (credit)	5	4	3
Actuarial (gain) loss	9	7	11
Net periodic defined benefit costs (credits)	$ 6	$ 6	$ 9
Amortization period for the deferred recovery of a regulatory asset	15 years	15 years	15 years
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	$ (4)	$ (3)	$ (4)
Other Changes in Plan Assets and Benefit Obligations Recognized in OCI and Regulatory Assets/Liabilities - Gross: [Abstract]
Net (gain) loss	(9)	22	8
Prior service costs (credit)	7	0	10
Amortization of: [Abstract]
Prior service (cost) credit	(5)	(4)	(3)
Actuarial gain (loss)	(9)	(7)	(11)
Total recognized in OCI and regulatory assets/liabilities	(16)	11	4
Total recognized in net periodic benefit costs, OCI and regulatory assets/liabilities	(10)	17	13
Other Changes in Plan Assets and Benefit Obligations Recognized in OCI and Regulatory Assets/Liabilities - Gross (Details) [Abstract]
Total recognized in OCI and regulatory assets/liabilities	(16)	11	4
Estimated Amounts to be Amortized From AOCI and Regulatory Assets into Net Periodic Benefit Costs in the Next Fiscal Period (Details) [Abstract]
Prior service cost (credit)	5
Actuarial (gain) loss	9
Total	14
Amortization from Balance Sheet: [Abstract]
Total	14
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Net periodic defined benefit costs (credits) charged to operating expense or regulatory assets, excluding amounts charged to construction and other non-expense accounts	$ 8	$ 8	$ 12
Amortization period for the deferred recovery of a regulatory asset	15 years	15 years	15 years
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	$ 4	$ 3	$ 4
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Qualified Plan [Member]
Amortization of:
Settlements	5
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | LKE [Member]
Net Periodic Defined Benefit Costs Allocated to Subsidiary by Sponsor (Numeric) [Abstract]
Costs allocated to subsidiary by plan sponsors	$ 5	$ 4	$ 5
Louisville Gas And Electric Co [Member] | Other Postretirement Benefits Plan [Member]
Amortization of:
Amortization period for the deferred recovery of a regulatory asset	15 years	15 years	15 years
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	$ (4)	$ (3)	$ (4)
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Net periodic defined benefit costs (credits) charged to operating expense or regulatory assets, excluding amounts charged to construction and other non-expense accounts	$ 3	$ 3	$ 4
Amortization period for the deferred recovery of a regulatory asset	15 years	15 years	15 years
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	$ 4	$ 3	$ 4
Louisville Gas And Electric Co [Member] | Other Postretirement Benefits Plan [Member] | LKE [Member]
Net Periodic Defined Benefit Costs Allocated to Subsidiary by Sponsor (Numeric) [Abstract]
Costs allocated to subsidiary by plan sponsors	$ 3	$ 3	$ 4
Kentucky Utilities Co [Member] | Pension Plan [Member] | U.S. [Member]
Amortization of:
Amortization period for the deferred recovery of a regulatory asset	15 years	15 years	15 years
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	$ (2)	$ (2)	$ (1)
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Net periodic defined benefit costs (credits) charged to operating expense or regulatory assets, excluding amounts charged to construction and other non-expense accounts	$ 4	$ 5	$ 9
Amortization period for the deferred recovery of a regulatory asset	15 years	15 years	15 years
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	$ 2	$ 2	$ 1
Kentucky Utilities Co [Member] | Other Postretirement Benefits Plan [Member]
Amortization of:
Amortization period for the deferred recovery of a regulatory asset	15 years	15 years	15 years
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	$ (2)	$ (2)	$ (1)
Net Periodic Defined Benefit Costs (Credits) Charged to Operating Expense or Regulatory Assets, Excluding Amounts Charged to Construction and Other Non-expense Accounts (Details) [Abstract]
Net periodic defined benefit costs (credits) charged to operating expense or regulatory assets, excluding amounts charged to construction and other non-expense accounts	$ 1	$ 2	$ 2
Amortization period for the deferred recovery of a regulatory asset	15 years	15 years	15 years
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period	$ 2	$ 2	$ 1