Retirement and Postemployment Benefits (Plan Assets and Expected Cash Flows) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Pension Plan [Member] | U.S. [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	$ 3,109	$ 3,488	$ 3,243	$ 3,109	$ 3,488
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	3,109	3,488	3,243
Balance at end of period		3,109	3,488
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract]
Employer contributions		$ 153	65
Amount to be contributed to plan in the next fiscal year				0
Expected amount of benefit payments in the next period for non-qualified plans				13
Estimated Future Benefit Payments (Details) [Abstract]
2019				274
2020				266
2021				265
2022				265
2023				264
2024-2028				1,290
Pension Plan [Member] | U.S. [Member] | Subsequent Event [Member]
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract]
Employer contributions	50
Pension Plan [Member] | U.S. [Member] | Master Trust [Member]
Assumptions Used in Calculations (Numeric) [Abstract]
The limited lives of four partnership of private equity investments (in years)		10 years
The amount of potential liability that maybe required to be funded by the master trust during life of the partnership				$ 71
Number Of Days Notice Required To Redeem Shares		45 days
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				100.00%	100.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				100.00%
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	3,109	$ 3,488	3,488	$ 3,109	$ 3,488
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	3,109	3,488
Balance at end of period		3,109	3,488
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	591	716	716	591	716
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	591	716
Balance at end of period		591	716
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	924	931	931	924	931
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	924	931
Balance at end of period		924	931
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	46	37	40	46	37
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	46	37	40
Actual return on plan assets relating to assets still held at the reporting date		(1)	1
Actual return on plan assets relating to assets sold during the period		3
Purchases, sales and settlements		7	(4)
Balance at end of period		46	37
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				220	301
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				220	301
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Equity Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				340	364
Measured at fair value not using net asset value per share				159	229
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Equity Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				159	229
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Equity Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Equity Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | International Equity Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				466	538
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Commingled Debt Equity Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				543	611
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				212	186
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				212	186
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Corporate Debt Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				899	883
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Corporate Debt Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Corporate Debt Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				874	870
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Corporate Debt Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				25	13
Fair value at end of period	25	13	13	25	13
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	25	13	13
Actual return on plan assets relating to assets still held at the reporting date		(2)	0
Actual return on plan assets relating to assets sold during the period		3
Purchases, sales and settlements		11	0
Balance at end of period		25	13
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Other Debt Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				17	10
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Other Debt Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Other Debt Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				17	10
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Other Debt Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Real Estate Alternative Investments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				90	109
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Total Trust Assets Prior to Adjustments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	3,240	3,561	3,561	3,240	3,561
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	3,240	3,561
Balance at end of period		3,240	3,561
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Private Equity Alternative Investments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				65	80
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Hedge Fund Of Funds Alternative Investments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				175	175
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Derivatives [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				33	51
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Derivatives [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Derivatives [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				33	51
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Derivatives [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Insurance Contracts [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				21	24
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Insurance Contracts [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Insurance Contracts [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Insurance Contracts [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				21	24
Fair value at end of period	21	24	27	21	24
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	21	24	27
Actual return on plan assets relating to assets still held at the reporting date		1	1
Actual return on plan assets relating to assets sold during the period		0
Purchases, sales and settlements		(4)	(4)
Balance at end of period		21	24
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Receivables And Payables Net [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	(2)	72	72	(2)	72
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	(2)	72
Balance at end of period		(2)	72
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Account 401 H [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	(129)	(145)	(145)	$ (129)	$ (145)
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	(129)	(145)
Balance at end of period		(129)	(145)
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Growth Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				55.00%	56.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				55.00%
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Growth Portfolio [Member] | Equity Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				30.00%	32.00%
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Growth Portfolio [Member] | Debt Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				15.00%	14.00%
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Growth Portfolio [Member] | Alternative Investments [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				10.00%	10.00%
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Immunizing Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				43.00%	43.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				43.00%
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Immunizing Portfolio [Member] | Debt Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				39.00%	39.00%
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Immunizing Portfolio [Member] | Derivatives [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				4.00%	4.00%
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Liquidity Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				2.00%	1.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				2.00%
Pension Plan [Member] | U.K. [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				100.00%	100.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				100.00%
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	7,801	8,490	7,211	$ 7,801	$ 8,490
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	7,801	8,490	7,211
Balance at end of period		7,801	8,490
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract]
Employer contributions		$ 188	486
Amount to be contributed to plan in the next fiscal year				277
Recurrence of formal actuarial valuations (in years)		3 years
Percentage of deficit funding requirements permitted to recover in rates		78.00%
Estimated Future Benefit Payments (Details) [Abstract]
2019				337
2020				340
2021				344
2022				349
2023				352
2024-2028				1,781
Pension Plan [Member] | U.K. [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	147	$ 216	216	147	216
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	147	216
Balance at end of period		147	216
Pension Plan [Member] | U.K. [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	2,937	3,140	3,140	2,937	3,140
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	2,937	3,140
Balance at end of period		2,937	3,140
Pension Plan [Member] | U.K. [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	0	0	0	$ 0	$ 0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	0	0
Balance at end of period		0	0
Pension Plan [Member] | U.K. [Member] | Cash And Cash Equivalents [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				2.00%	2.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				0.00%
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				$ 147	$ 216
Pension Plan [Member] | U.K. [Member] | Cash And Cash Equivalents [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				147	216
Pension Plan [Member] | U.K. [Member] | Cash And Cash Equivalents [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.K. [Member] | Cash And Cash Equivalents [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				$ 0	$ 0
Pension Plan [Member] | U.K. [Member] | U.K. Companies Equity Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				0.00%	2.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				2.00%
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				$ 27	$ 157
Pension Plan [Member] | U.K. [Member] | European Companies Excluding U.K. Equity Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				1.00%	1.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				1.00%
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				$ 76	$ 98
Pension Plan [Member] | U.K. [Member] | Asian Pacific Companies Equity Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				1.00%	1.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				1.00%
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				$ 49	$ 60
Pension Plan [Member] | U.K. [Member] | North American Companies Equity Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				1.00%	1.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				1.00%
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				$ 105	$ 123
Pension Plan [Member] | U.K. [Member] | Emerging Markets Companies Equity Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				1.00%	1.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				1.00%
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				$ 44	$ 62
Pension Plan [Member] | U.K. [Member] | Global Equities Equity Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				19.00%	16.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				10.00%
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				$ 1,465	$ 1,335
Pension Plan [Member] | U.K. [Member] | Global Tactical Asset Allocation Equity Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				31.00%	33.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				41.00%
Pension Plan [Member] | U.K. [Member] | Other Equity Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				$ 2,437	$ 2,807
Pension Plan [Member] | U.K. [Member] | Debt Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				38.00%	37.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				38.00%
Pension Plan [Member] | U.K. [Member] | U.K. Corporate Bonds Debt Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				$ 4	$ 3
Pension Plan [Member] | U.K. [Member] | U.K. Corporate Bonds Debt Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.K. [Member] | U.K. Corporate Bonds Debt Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				4	3
Pension Plan [Member] | U.K. [Member] | U.K. Corporate Bonds Debt Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.K. [Member] | U.K. Gilts Debt Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				2,933	3,137
Pension Plan [Member] | U.K. [Member] | U.K. Gilts Debt Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Pension Plan [Member] | U.K. [Member] | U.K. Gilts Debt Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				2,933	3,137
Pension Plan [Member] | U.K. [Member] | U.K. Gilts Debt Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				$ 0	$ 0
Pension Plan [Member] | U.K. [Member] | Alternative Investments [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				6.00%	6.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				5.00%
Pension Plan [Member] | U.K. [Member] | Real Estate Alternative Investments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				$ 485	$ 492
Pension Plan [Member] | U.K. [Member] | Total Trust Assets Prior to Adjustments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	7,772	8,490	8,490	7,772	8,490
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	7,772	8,490
Balance at end of period		7,772	8,490
Pension Plan [Member] | U.K. [Member] | Receivables And Payables Net [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	29	0	0	$ 29	$ 0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	29	0
Balance at end of period		29	0
Other Postretirement Benefits Plan [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				100.00%	100.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				100.00%
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	301	405	378	$ 301	$ 405
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	301	405	378
Balance at end of period		301	405
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract]
Employer contributions		23	15
Amount to be contributed to plan in the next fiscal year				15
Estimated Future Benefit Payments (Details) [Abstract]
2019				50
2020				50
2021				49
2022				48
2023				46
2024-2028				210
Expected Federal Subsidy (Details) [Abstract]
Federal subsidy 2019				0
Federal subsidy 2020				1
Federal subsidy 2021				0
Federal subsidy 2022				1
Federal subsidy 2023				0
Federal subsidy 2024-2028				1
Other Postretirement Benefits Plan [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	6	10	10	6	10
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	6	10
Balance at end of period		6	10
Other Postretirement Benefits Plan [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	28	30	30	28	30
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	28	30
Balance at end of period		28	30
Other Postretirement Benefits Plan [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	0	0	0	$ 0	$ 0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	0	0
Balance at end of period		$ 0	0
Other Postretirement Benefits Plan [Member] | Cash And Cash Equivalents [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				4.00%	4.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				5.00%
Other Postretirement Benefits Plan [Member] | Money Market Funds [Member]
Assumptions Used in Calculations (Numeric) [Abstract]
Number of months from date of purchase that investment must mature		13 months
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	6	$ 10	10	$ 6	$ 10
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	6	10
Balance at end of period		6	10
Other Postretirement Benefits Plan [Member] | Money Market Funds [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				6	10
Other Postretirement Benefits Plan [Member] | Money Market Funds [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Other Postretirement Benefits Plan [Member] | Money Market Funds [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				$ 0	$ 0
Other Postretirement Benefits Plan [Member] | Equity Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				40.00%	47.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				45.00%
Other Postretirement Benefits Plan [Member] | United States Large Cap Equity Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				$ 69	$ 123
Other Postretirement Benefits Plan [Member] | Commingled Debt Equity Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				$ 68	$ 96
Other Postretirement Benefits Plan [Member] | Debt Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				56.00%	49.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				50.00%
Other Postretirement Benefits Plan [Member] | Corporate Debt Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	28	30	30	$ 28	$ 30
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	28	30
Balance at end of period		28	30
Other Postretirement Benefits Plan [Member] | Corporate Debt Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Other Postretirement Benefits Plan [Member] | Corporate Debt Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				28	30
Other Postretirement Benefits Plan [Member] | Corporate Debt Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Other Postretirement Benefits Plan [Member] | Total Trust Assets Prior to Adjustments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	171	259	259	171	259
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	171	259
Balance at end of period		171	259
Other Postretirement Benefits Plan [Member] | Receivables And Payables Net [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	1	1	1	1	1
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	1	1
Balance at end of period		1	1
Other Postretirement Benefits Plan [Member] | Account 401 H [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	129	145	145	129	145
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	129	145
Balance at end of period		129	145
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	1,294	1,402	1,315	1,294	1,402
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	1,294	1,402	1,315
Balance at end of period		1,294	1,402
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract]
Employer contributions		$ 109	$ 21
Amount to be contributed to plan in the next fiscal year				0
Expected amount of benefit payments in the next period for non-qualified plans				4
Estimated Future Benefit Payments (Details) [Abstract]
2019				112
2020				112
2021				113
2022				113
2023				112
2024-2028				547
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Subsequent Event [Member]
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract]
Employer contributions	20
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member]
Information About Plan Assets (Numeric) [Abstract]
Value of plan U.S. pension trust assets that relate to PPL subsidiary				1,300	$ 1,400
Undivided interest percentage in each asset category that PPL subsidiary holds		42.00%	40.00%
Assumptions Used in Calculations (Numeric) [Abstract]
The limited lives of four partnership of private equity investments (in years)		10 years
The amount of potential liability that maybe required to be funded by the master trust during life of the partnership				$ 71
Number Of Days Notice Required To Redeem Shares		45 days
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				100.00%	100.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				100.00%
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	3,240	$ 3,561	$ 3,561	$ 3,240	$ 3,561
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	3,240	3,561
Balance at end of period		3,240	3,561
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	591	716	716	591	716
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	591	716
Balance at end of period		591	716
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	924	931	931	924	931
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	924	931
Balance at end of period		924	931
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	46	37	40	46	37
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	46	37	40
Actual return on plan assets relating to assets still held at the reporting date		(1)	1
Actual return on plan assets relating to assets sold during the period		3
Purchases, sales and settlements		7	(4)
Balance at end of period		46	37
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				220	301
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				220	301
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Equity Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				340	364
Measured at fair value not using net asset value per share				159	229
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Equity Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				159	229
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Equity Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Equity Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | International Equity Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				466	538
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Commingled Debt Equity Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				543	611
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				212	186
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				212	186
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Corporate Debt Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				899	883
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Corporate Debt Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Corporate Debt Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				874	870
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Corporate Debt Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				25	13
Fair value at end of period	25	13	13	25	13
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	25	13	13
Actual return on plan assets relating to assets still held at the reporting date		(2)	0
Actual return on plan assets relating to assets sold during the period		3
Purchases, sales and settlements		11	0
Balance at end of period		25	13
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Other Debt Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				17	10
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Other Debt Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Other Debt Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				17	10
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Other Debt Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Real Estate Alternative Investments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				90	109
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Total Trust Assets Prior to Adjustments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	3,109	3,488	3,488	3,109	3,488
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	3,109	3,488
Balance at end of period		3,109	3,488
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Private Equity Alternative Investments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				65	80
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Hedge Fund Of Funds Alternative Investments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				175	175
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Derivatives [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				33	51
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Derivatives [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Derivatives [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				33	51
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Derivatives [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Insurance Contracts [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				21	24
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Insurance Contracts [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Insurance Contracts [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Insurance Contracts [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				21	24
Fair value at end of period	21	24	27	21	24
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	21	24	27
Actual return on plan assets relating to assets still held at the reporting date		1	1
Actual return on plan assets relating to assets sold during the period		0
Purchases, sales and settlements		(4)	(4)
Balance at end of period		21	24
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Receivables And Payables Net [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	(2)	72	72	(2)	72
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	(2)	72
Balance at end of period		(2)	72
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Account 401 H [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	(129)	(145)	(145)	$ (129)	$ (145)
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	(129)	(145)
Balance at end of period		(129)	(145)
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Growth Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				55.00%	56.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				55.00%
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Growth Portfolio [Member] | Equity Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				30.00%	32.00%
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Growth Portfolio [Member] | Debt Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				15.00%	14.00%
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Growth Portfolio [Member] | Alternative Investments [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				10.00%	10.00%
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Immunizing Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				43.00%	43.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				43.00%
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Immunizing Portfolio [Member] | Debt Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				39.00%	39.00%
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Immunizing Portfolio [Member] | Derivatives [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				4.00%	4.00%
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Liquidity Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				2.00%	1.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				2.00%
LG And E And KU Energy LLC [Member] | Other Postretirement Benefits Plan [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	117	116	98	$ 117	$ 116
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	117	116	98
Balance at end of period		117	116
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract]
Employer contributions		24	15
Amount to be contributed to plan in the next fiscal year				15
Estimated Future Benefit Payments (Details) [Abstract]
2019				15
2020				15
2021				16
2022				16
2023				16
2024-2028				78
Expected Federal Subsidy (Details) [Abstract]
Federal subsidy 2019				0
Federal subsidy 2020				0
Federal subsidy 2021				0
Federal subsidy 2022				1
Federal subsidy 2023				0
Federal subsidy 2024-2028				1
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	281	325	318	281	325
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	281	325	318
Balance at end of period		281	325
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract]
Employer contributions		$ 10	$ 0
Amount to be contributed to plan in the next fiscal year				0
Estimated Future Benefit Payments (Details) [Abstract]
2019				25
2020				25
2021				24
2022				23
2023				22
2024-2028				95
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Subsequent Event [Member]
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract]
Employer contributions	1
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member]
Information About Plan Assets (Numeric) [Abstract]
Value of plan U.S. pension trust assets that relate to PPL subsidiary				281	$ 325
Undivided interest percentage in each asset category that PPL subsidiary holds		9.00%	9.00%
Assumptions Used in Calculations (Numeric) [Abstract]
The limited lives of four partnership of private equity investments (in years)		10 years
The amount of potential liability that maybe required to be funded by the master trust during life of the partnership				$ 71
Number Of Days Notice Required To Redeem Shares		45 days
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				100.00%	100.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				100.00%
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	3,240	$ 3,561	$ 3,561	$ 3,240	$ 3,561
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	3,240	3,561
Balance at end of period		3,240	3,561
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	591	716	716	591	716
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	591	716
Balance at end of period		591	716
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	924	931	931	924	931
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	924	931
Balance at end of period		924	931
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	46	37	40	46	37
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	46	37	40
Actual return on plan assets relating to assets still held at the reporting date		(1)	1
Actual return on plan assets relating to assets sold during the period		3
Purchases, sales and settlements		7	(4)
Balance at end of period		46	37
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				220	301
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				220	301
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Equity Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				340	364
Measured at fair value not using net asset value per share				159	229
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Equity Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				159	229
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Equity Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Equity Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | International Equity Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				466	538
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Commingled Debt Equity Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				543	611
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				212	186
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				212	186
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Corporate Debt Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				899	883
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Corporate Debt Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Corporate Debt Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				874	870
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Corporate Debt Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				25	13
Fair value at end of period	25	13	13	25	13
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	25	13	13
Actual return on plan assets relating to assets still held at the reporting date		(2)	0
Actual return on plan assets relating to assets sold during the period		3
Purchases, sales and settlements		11	0
Balance at end of period		25	13
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Other Debt Securities [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				17	10
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Other Debt Securities [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Other Debt Securities [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				17	10
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Other Debt Securities [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Real Estate Alternative Investments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				90	109
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Total Trust Assets Prior to Adjustments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	3,109	3,488	3,488	3,109	3,488
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	3,109	3,488
Balance at end of period		3,109	3,488
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Private Equity Alternative Investments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				65	80
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Hedge Fund Of Funds Alternative Investments [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value using net asset value per share				175	175
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Derivatives [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				33	51
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Derivatives [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Derivatives [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				33	51
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Derivatives [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Insurance Contracts [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				21	24
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Insurance Contracts [Member] | Level 1 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Insurance Contracts [Member] | Level 2 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				0	0
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Insurance Contracts [Member] | Level 3 [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Measured at fair value not using net asset value per share				21	24
Fair value at end of period	21	24	27	21	24
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	21	24	27
Actual return on plan assets relating to assets still held at the reporting date		1	1
Actual return on plan assets relating to assets sold during the period		0
Purchases, sales and settlements		(4)	(4)
Balance at end of period		21	24
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Receivables And Payables Net [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	(2)	72	72	(2)	72
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	(2)	72
Balance at end of period		(2)	72
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Account 401 H [Member]
Defined benefit plan fair value of plan assets (Details) [Abstract]
Fair value at end of period	(129)	(145)	(145)	$ (129)	$ (145)
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	$ (129)	(145)
Balance at end of period		$ (129)	$ (145)
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Growth Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				55.00%	56.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				55.00%
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Growth Portfolio [Member] | Equity Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				30.00%	32.00%
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Growth Portfolio [Member] | Debt Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				15.00%	14.00%
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Growth Portfolio [Member] | Alternative Investments [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				10.00%	10.00%
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Immunizing Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				43.00%	43.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				43.00%
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Immunizing Portfolio [Member] | Debt Securities [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				39.00%	39.00%
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Immunizing Portfolio [Member] | Derivatives [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				4.00%	4.00%
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Liquidity Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Percentage of trust assets				2.00%	1.00%
Target Allocations (Details ) [Abstract]
Target asset allocation				2.00%