Retirement and Postemployment Benefits (Weighted-Average Assumptions, Cost Trend Rates and Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amounts recognized in the Balance Sheets consist of: [Abstract]
Noncurrent asset	$ 284	$ 9
Pension Plan [Member] | U.S. [Member]
Weighted Average Assumptions Used in the Valuation of the Benefit Obligations (Details) [Abstract]
Benefit obligations valuation discount rate	3.70%	4.21%
Benefit obligations valuation rate of compensation increase	3.78%	3.95%
Weighted Average Assumptions Used to Determine the Net Periodic Benefit Costs (Details) [Abstract]
Net periodic benefit costs discount rate - service cost	4.21%	4.59%	4.25%
Net periodic benefit costs discount rate - interest cost	4.21%	4.59%	4.25%
Net periodic benefit costs rate of compensation increase	3.95%	3.93%	3.91%
Net periodic benefit costs expected return on plan assets	7.00%	7.00%	7.00%
Assumed Health Care Cost Trend Rates (Details) [Abstract]
Health care cost trend rate assumed for next year, obligations	6.60%	7.00%	6.80%
Health care cost trend rate assumed for next year, cost	7.00%	6.80%	7.20%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate), obligations	5.00%	5.00%	5.00%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate), cost	5.00%	5.00%	5.00%
Year that the rate reaches the ultimate trend rate, obligations	2022	2022	2020
Year that the rate reaches the ultimate trend rate, cost	2022	2020	2020
Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of period	$ 4,079	$ 3,863
Service cost	65	66	$ 96
Interest cost	168	174	194
Participant contributions	0	0
Plan Amendments	(1)	14
Actuarial (gain) loss	233	214
Settlements	(6)	(9)
Termination benefits	1	0
Gross benefits paid	(251)	(243)
Federal subsidy	0	0
Currency conversion	0	0
Benefit Obligation, end of period	4,288	4,079	3,863
Change in Plan Assets [Roll Forward]
Balance at beginning of period	3,243	3,227
Actual return on plan assets	437	189
Employer contributions	65	79
Participant contributions	0	0
Settlements	(6)	(9)
Gross benefits paid	(251)	(243)
Currency conversion	0	0
Balance at end of period	3,488	3,243	$ 3,227
Funded Status, end of period	(800)	(836)
Amounts recognized in the Balance Sheets consist of: [Abstract]
Noncurrent asset	0	0
Current liability	(13)	(17)
Noncurrent liability	(787)	(819)
Net amount recognized, end of period	(800)	(836)
Amounts recognized in AOCI and regulatory assets/liabilities (pre-tax): [Abstract]
Prior service cost (credit)	49	59
Net actuarial (gain) loss	1,134	1,178
Total	1,183	1,237
Total accumulated benefit obligation for defined benefit pension plans	4,000	3,807
Changes in Plan Assets and Benefit Obligations Recognized in AOCI and Regulatory Assets/Liabilities by Type (Details) [Abstract]
AOCI	374	357
Regulatory assets/liabilities	809	880
Total	1,183	1,237
Pension Plans Where the Projected or Accumulated Benefit Obligation Exceed the Fair Value of Plan Assets (Details) [Abstract]
Projected benefit obligations	4,288	4,079
Fair value of plan assets where the projected benefit obligations exceed the value of plan assets	3,488	3,243
Accumulated benefit obligation	4,000	3,807
Fair value of plan assets where the accumulated benefit obligations exceed the value of plan assets	$ 3,488	$ 3,243
Pension Plan [Member] | U.K. [Member]
Weighted Average Assumptions Used in the Valuation of the Benefit Obligations (Details) [Abstract]
Benefit obligations valuation discount rate	2.65%	2.87%
Benefit obligations valuation rate of compensation increase	3.50%	3.50%
Weighted Average Assumptions Used to Determine the Net Periodic Benefit Costs (Details) [Abstract]
Net periodic benefit costs discount rate - service cost	2.99%	3.90%	3.85%
Net periodic benefit costs discount rate - interest cost	2.41%	3.14%	3.85%
Net periodic benefit costs rate of compensation increase	3.50%	4.00%	4.00%
Net periodic benefit costs expected return on plan assets	7.22%	7.20%	7.19%
Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of period	$ 7,383	$ 8,404
Service cost	76	69	$ 79
Interest cost	178	235	314
Participant contributions	13	14
Plan Amendments	0	0
Actuarial (gain) loss	293	484
Settlements	(1)	0
Termination benefits	0	0
Gross benefits paid	(345)	(357)
Federal subsidy	0	0
Currency conversion	622	(1,466)
Benefit Obligation, end of period	8,219	7,383	8,404
Change in Plan Assets [Roll Forward]
Balance at beginning of period	7,211	7,625
Actual return on plan assets	480	979
Employer contributions	486	330
Participant contributions	13	14
Settlements	(1)	0
Gross benefits paid	(345)	(357)
Currency conversion	646	(1,380)
Balance at end of period	8,490	7,211	$ 7,625
Funded Status, end of period	271	(172)
Amounts recognized in the Balance Sheets consist of: [Abstract]
Noncurrent asset	284	10
Current liability	0	0
Noncurrent liability	(13)	(182)
Net amount recognized, end of period	271	(172)
Amounts recognized in AOCI and regulatory assets/liabilities (pre-tax): [Abstract]
Prior service cost (credit)	0	0
Net actuarial (gain) loss	2,755	2,553
Total	2,755	2,553
Total accumulated benefit obligation for defined benefit pension plans	7,542	6,780
Changes in Plan Assets and Benefit Obligations Recognized in AOCI and Regulatory Assets/Liabilities by Type (Details) [Abstract]
Total	2,755	2,553
Pension Plans Where the Projected or Accumulated Benefit Obligation Exceed the Fair Value of Plan Assets (Details) [Abstract]
Projected benefit obligations	3,083	3,403
Fair value of plan assets where the projected benefit obligations exceed the value of plan assets	3,070	3,221
Accumulated benefit obligation	10	657
Fair value of plan assets where the accumulated benefit obligations exceed the value of plan assets	$ 0	$ 643
Other Postretirement Benefits Plan [Member]
Weighted Average Assumptions Used in the Valuation of the Benefit Obligations (Details) [Abstract]
Benefit obligations valuation discount rate	3.64%	4.11%
Benefit obligations valuation rate of compensation increase	3.75%	3.92%
Weighted Average Assumptions Used to Determine the Net Periodic Benefit Costs (Details) [Abstract]
Net periodic benefit costs discount rate - service cost	4.11%	4.48%	4.09%
Net periodic benefit costs discount rate - interest cost	4.11%	4.48%	4.09%
Net periodic benefit costs rate of compensation increase	3.92%	3.91%	3.86%
Net periodic benefit costs expected return on plan assets	6.21%	6.11%	6.06%
Effect of One Percentage Point Change in Assumed Health Care Costs Trend Rate (Details) [Abstract]
Effect on accumulated postretirement benefit obligation of a one percentage point increase	$ 4
Effect on accumulated postretirement benefit obligation of a one percentage point decrease	(4)
Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of period	591	$ 596
Service cost	7	7	$ 11
Interest cost	23	26	26
Participant contributions	14	14
Plan Amendments	8	0
Actuarial (gain) loss	4	11
Settlements	0	0
Termination benefits	0	0
Gross benefits paid	(59)	(64)
Federal subsidy	1	1
Currency conversion	0	0
Benefit Obligation, end of period	589	591	596
Change in Plan Assets [Roll Forward]
Balance at beginning of period	378	379
Actual return on plan assets	54	25
Employer contributions	15	19
Participant contributions	13	14
Settlements	0	0
Gross benefits paid	(55)	(59)
Currency conversion	0	0
Balance at end of period	405	378	379
Funded Status, end of period	(184)	(213)
Amounts recognized in the Balance Sheets consist of: [Abstract]
Noncurrent asset	2	2
Current liability	(3)	(3)
Noncurrent liability	(183)	(212)
Net amount recognized, end of period	(184)	(213)
Amounts recognized in AOCI and regulatory assets/liabilities (pre-tax): [Abstract]
Prior service cost (credit)	9	0
Net actuarial (gain) loss	16	45
Total	25	45
Changes in Plan Assets and Benefit Obligations Recognized in AOCI and Regulatory Assets/Liabilities by Type (Details) [Abstract]
AOCI	15	20
Regulatory assets/liabilities	10	25
Total	25	45
PPL Electric Utilities Corp [Member]
Change in Plan Assets [Roll Forward]
Non-cash contributions related to remeasurement and separation of benefit plans			56
PPL Electric Utilities Corp [Member] | Pension Plan [Member] | U.S. [Member] | PPL Services Funded Status Allocation [Member]
Change in Plan Assets [Roll Forward]
Funded Status, end of period	246	281
Non-cash contributions related to remeasurement and separation of benefit plans			$ 56
PPL Electric Utilities Corp [Member] | Other Postretirement Benefits Plan [Member] | PPL Services Funded Status Allocation [Member]
Change in Plan Assets [Roll Forward]
Funded Status, end of period	$ 62	$ 72
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member]
Weighted Average Assumptions Used in the Valuation of the Benefit Obligations (Details) [Abstract]
Benefit obligations valuation discount rate	3.69%	4.19%
Benefit obligations valuation rate of compensation increase	3.50%	3.50%
Weighted Average Assumptions Used to Determine the Net Periodic Benefit Costs (Details) [Abstract]
Net periodic benefit costs discount rate	4.19%	4.56%	4.25%
Net periodic benefit costs rate of compensation increase	3.50%	3.50%	3.50%
Net periodic benefit costs expected return on plan assets	7.00%	7.00%	7.00%
Assumed Health Care Cost Trend Rates (Details) [Abstract]
Health care cost trend rate assumed for next year, obligations	6.60%	7.00%	6.80%
Health care cost trend rate assumed for next year, cost	7.00%	6.80%	7.20%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate), obligations	5.00%	5.00%	5.00%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate), cost	5.00%	5.00%	5.00%
Year that the rate reaches the ultimate trend rate, obligations	2022	2022	2020
Year that the rate reaches the ultimate trend rate, cost	2022	2020	2020
Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of period	$ 1,669	$ 1,588
Service cost	24	23	$ 26
Interest cost	68	71	68
Participant contributions	0	0
Plan Amendments	6	0
Actuarial (gain) loss	113	96
Gross benefits paid	(109)	(109)
Benefit Obligation, end of period	1,771	1,669	1,588
Increase during the period resulting from a plan amendment		19
Defined Benefit Plan One Time Cash Payouts To Terminated Vested Employees	50	53
Change in Plan Assets [Roll Forward]
Balance at beginning of period	1,315	1,289
Actual return on plan assets	175	69
Employer contributions	21	66
Participant contributions	0	0
Gross benefits paid	(109)	(109)
Balance at end of period	1,402	1,315	$ 1,289
Funded Status, end of period	(369)	(354)
Amounts recognized in the Balance Sheets consist of: [Abstract]
Noncurrent asset	0	0
Current liability	(4)	(4)
Noncurrent liability	(365)	(350)
Net amount recognized, end of period	(369)	(354)
Amounts recognized in AOCI and regulatory assets/liabilities (pre-tax): [Abstract]
Prior service cost (credit)	44	45
Net actuarial (gain) loss	434	436
Total	478	481
Total accumulated benefit obligation for defined benefit pension plans	1,616	1,531
Changes in Plan Assets and Benefit Obligations Recognized in AOCI and Regulatory Assets/Liabilities by Type (Details) [Abstract]
AOCI	144	111
Regulatory assets/liabilities	334	370
Total	478	481
Pension Plans Where the Projected or Accumulated Benefit Obligation Exceed the Fair Value of Plan Assets (Details) [Abstract]
Projected benefit obligations	1,771	1,669
Fair value of plan assets where the projected benefit obligations exceed the value of plan assets	1,402	1,315
Accumulated benefit obligation	1,616	1,531
Fair value of plan assets where the accumulated benefit obligations exceed the value of plan assets	$ 1,402	$ 1,315
LG And E And KU Energy LLC [Member] | Other Postretirement Benefits Plan [Member]
Weighted Average Assumptions Used in the Valuation of the Benefit Obligations (Details) [Abstract]
Benefit obligations valuation discount rate	3.65%	4.12%
Benefit obligations valuation rate of compensation increase	3.50%	3.50%
Weighted Average Assumptions Used to Determine the Net Periodic Benefit Costs (Details) [Abstract]
Net periodic benefit costs discount rate	4.12%	4.49%	4.06%
Net periodic benefit costs rate of compensation increase	3.50%	3.50%	3.50%
Net periodic benefit costs expected return on plan assets	6.82%	6.82%	6.82%
Effect of One Percentage Point Change in Assumed Health Care Costs Trend Rate (Details) [Abstract]
Effect on accumulated postretirement benefit obligation of a one percentage point increase	$ 3
Effect on accumulated postretirement benefit obligation of a one percentage point decrease	(3)
Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of period	220	$ 216
Service cost	4	5	$ 5
Interest cost	9	9	9
Participant contributions	8	7
Plan Amendments	8	0
Actuarial (gain) loss	(7)	4
Gross benefits paid	(19)	(21)
Benefit Obligation, end of period	223	220	216
Change in Plan Assets [Roll Forward]
Balance at beginning of period	98	88
Actual return on plan assets	14	4
Employer contributions	15	20
Participant contributions	8	7
Gross benefits paid	(19)	(21)
Balance at end of period	116	98	$ 88
Funded Status, end of period	(107)	(122)
Amounts recognized in the Balance Sheets consist of: [Abstract]
Noncurrent asset	2	2
Current liability	(3)	(3)
Noncurrent liability	(106)	(121)
Net amount recognized, end of period	(107)	(122)
Amounts recognized in AOCI and regulatory assets/liabilities (pre-tax): [Abstract]
Prior service cost (credit)	13	6
Net actuarial (gain) loss	(26)	(13)
Total	(13)	(7)
Changes in Plan Assets and Benefit Obligations Recognized in AOCI and Regulatory Assets/Liabilities by Type (Details) [Abstract]
AOCI	6	8
Regulatory assets/liabilities	(19)	(15)
Total	$ (13)	$ (7)
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member]
Weighted Average Assumptions Used in the Valuation of the Benefit Obligations (Details) [Abstract]
Benefit obligations valuation discount rate	3.65%	4.13%
Weighted Average Assumptions Used to Determine the Net Periodic Benefit Costs (Details) [Abstract]
Net periodic benefit costs discount rate	4.13%	4.49%	4.20%
Net periodic benefit costs expected return on plan assets	7.00%	7.00%	7.00%
Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of period	$ 329	$ 326
Service cost	1	1	$ 1
Interest cost	13	15	14
Plan Amendments	6	0
Actuarial (gain) loss	11	15
Gross benefits paid	(34)	(28)
Benefit Obligation, end of period	326	329	326
Increase during the period resulting from a plan amendment		10
Defined Benefit Plan One Time Cash Payouts To Terminated Vested Employees	19	14
Change in Plan Assets [Roll Forward]
Balance at beginning of period	318	297
Actual return on plan assets	41	14
Employer contributions	0	35
Gross benefits paid	(34)	(28)
Balance at end of period	325	318	$ 297
Funded Status, end of period	(1)	(11)
Amounts recognized in the Balance Sheets consist of: [Abstract]
Noncurrent liability	(1)	(11)
Net amount recognized, end of period	(1)	(11)
Amounts recognized in AOCI and regulatory assets/liabilities (pre-tax): [Abstract]
Prior service cost (credit)	27	25
Net actuarial (gain) loss	(92)	110
Total	119	135
Total accumulated benefit obligation for defined benefit pension plans	326	329
Changes in Plan Assets and Benefit Obligations Recognized in AOCI and Regulatory Assets/Liabilities by Type (Details) [Abstract]
Total	119	135
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | LKE Funded Status Allocation [Member]
Change in Plan Assets [Roll Forward]
Funded Status, end of period	44	42
Louisville Gas And Electric Co [Member] | Other Postretirement Benefits Plan [Member] | LKE Funded Status Allocation [Member]
Change in Plan Assets [Roll Forward]
Funded Status, end of period	74	76
Kentucky Utilities Co [Member] | Pension Plan [Member] | U.S. [Member] | LKE Funded Status Allocation [Member]
Change in Plan Assets [Roll Forward]
Funded Status, end of period	36	62
Kentucky Utilities Co [Member] | Other Postretirement Benefits Plan [Member] | LKE Funded Status Allocation [Member]
Change in Plan Assets [Roll Forward]
Funded Status, end of period	$ 32	$ 40