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v3.19.3.a.u2

Retirement and Postemployment Benefits (Plan Assets and Expected Cash Flows) (Details) - USD ($) $ in Millions | 1 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Jan. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2019 | Dec. 31, 2018
Pension Plan [Member] | U.S. [Member] |  |  |  |  |
Defined benefit plan fair value of plan assets (Details) [Abstract] |  |  |  |  |
Fair value at end of period | $ 3,585 | $ 3,585 | $ 3,488 | $ 3,585 | $ 3,109
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 3,585 | 3,109 | 3,488 |  |
Balance at end of period |  | 3,585 | 3,109 |  |
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract] |  |  |  |  |
Employer contributions |  | $ 63 | 153 |  |
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 |  |  |  | 9 |
Estimated Future Benefit Payments (Details) [Abstract] |  |  |  |  |
2020 |  |  |  | 271 |
2021 |  |  |  | 267 |
2022 |  |  |  | 266 |
2023 |  |  |  | 264 |
2024 |  |  |  | 265 |
2025-2029 |  |  |  | $ 1,278 |
Pension Plan [Member] | U.S. [Member] | Subsequent Event [Member] |  |  |  |  |
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract] |  |  |  |  |
Employer contributions | 52 |  |  |  |
Pension Plan [Member] | U.S. [Member] | Master Trust [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% |
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 |  |  |  | $ 63 |
Number Of Days Notice Required To Redeem Shares |  | 45 days |  |  |
Defined benefit plan fair value of plan assets (Details) [Abstract] |  |  |  |  |
Fair value at end of period | 3,585 | $ 3,109 | 3,109 | 3,585 | $ 3,109
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 3,585 | 3,109 |  |  |
Balance at end of period |  | 3,585 | 3,109 |  |
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 | 685 | 591 | 591 | 685 | 591
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 685 | 591 |  |  |
Balance at end of period |  | 685 | 591 |  |
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 | 949 | 924 | 924 | 949 | 924
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 949 | 924 |  |  |
Balance at end of period |  | 949 | 924 |  |
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 | 24 | 46 | 46 | 24 | 46
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 24 | 46 | 37 |  |
Actual return on plan assets relating to assets still held at the reporting date |  | 3 | (1) |  |
Actual return on plan assets relating to assets sold during the period |  | 3 | 3 |  |
Purchases, sales and settlements |  | (28) | 7 |  |
Balance at end of period |  | 24 | 46 |  |
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 |  |  |  | 182 | 220
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 |  |  |  | 182 | 220
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 |  |  |  | 451 | 340
Measured at fair value not using net asset value per share |  |  |  | 194 | 159
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 |  |  |  | 194 | 159
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 |  |  |  | 554 | 466
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 |  |  |  | 621 | 543
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 |  |  |  | 310 | 212
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 |  |  |  | 309 | 212
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 |  |  |  | 1 | 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 |  |  |  | 951 | 899
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 |  |  |  | 931 | 874
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 |  |  |  | 20 | 25
Fair value at end of period | 20 | 20 | 13 | 20 | 25
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 20 | 25 | 13 |  |
Actual return on plan assets relating to assets still held at the reporting date |  | (1) | (2) |  |
Actual return on plan assets relating to assets sold during the period |  | 3 | 3 |  |
Purchases, sales and settlements |  | (7) | 11 |  |
Balance at end of period |  | 20 | 25 |  |
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 |  |  |  | 14 | 17
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 |  |  |  | 14 | 17
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 |  |  |  | 88 | 90
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 | 3,628 | 3,240 | 3,240 | 3,628 | 3,240
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 3,628 | 3,240 |  |  |
Balance at end of period |  | 3,628 | 3,240 |  |
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 |  |  |  | 62 | 65
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 |  |  |  | 194 | 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 |  |  |  | 3 | 33
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 |  |  |  | 3 | 33
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 |  |  |  | 4 | 21
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 |  |  |  | 4 | 21
Fair value at end of period | 4 | 21 | 21 | 4 | 21
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 4 | 21 | 24 |  |
Actual return on plan assets relating to assets still held at the reporting date |  | 4 | 1 |  |
Actual return on plan assets relating to assets sold during the period |  | 0 | 0 |  |
Purchases, sales and settlements |  | (21) | (4) |  |
Balance at end of period |  | 4 | 21 |  |
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 | 99 | (2) | (2) | 99 | (2)
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 99 | (2) |  |  |
Balance at end of period |  | 99 | (2) |  |
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 | (142) | (129) | (129) | $ (142) | $ (129)
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | (142) | (129) |  |  |
Balance at end of period |  | (142) | (129) |  |
Pension Plan [Member] | U.S. [Member] | Master Trust [Member] | Growth Portfolio [Member] |  |  |  |  |
Actual Allocation by Plan Asset (Details) [Abstract] |  |  |  |  |
Percentage of trust assets |  |  |  | 57.00% | 55.00%
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 |  |  |  | 34.00% | 30.00%
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 |  |  |  | 14.00% | 15.00%
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 |  |  |  | 9.00% | 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 |  |  |  | 42.00% | 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 |  |  |  | 35.00% | 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 |  |  |  | 7.00% | 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 |  |  |  | 1.00% | 2.00%
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 | 8,945 | 7,801 | 7,801 | $ 8,945 | $ 7,801
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 8,945 | 7,801 | 8,490 |  |
Balance at end of period |  | 8,945 | 7,801 |  |
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract] |  |  |  |  |
Employer contributions |  | $ 278 | 188 |  |
Amount to be contributed to plan in the next fiscal year |  |  |  | 273 |
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] |  |  |  |  |
2020 |  |  |  | 353 |
2021 |  |  |  | 351 |
2022 |  |  |  | 356 |
2023 |  |  |  | 359 |
2024 |  |  |  | 364 |
2025-2029 |  |  |  | 1,826 |
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 | 154 | $ 147 | 147 | 154 | 147
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 154 | 147 |  |  |
Balance at end of period |  | 154 | 147 |  |
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 | 3,824 | 2,937 | 2,937 | 3,824 | 2,937
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 3,824 | 2,937 |  |  |
Balance at end of period |  | 3,824 | 2,937 |  |
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 |  |  |  | $ 154 | $ 147
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 |  |  |  | 154 | 147
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% | 0.00%
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 |  |  |  | $ 22 | $ 27
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 |  |  |  | 0.00% | 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 |  |  |  | $ 54 | $ 76
Pension Plan [Member] | U.K. [Member] | Asian Pacific Companies Equity Securities [Member] |  |  |  |  |
Actual Allocation by Plan Asset (Details) [Abstract] |  |  |  |  |
Percentage of trust assets |  |  |  | 0.00% | 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 |  |  |  | $ 35 | $ 49
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 |  |  |  | $ 74 | $ 105
Pension Plan [Member] | U.K. [Member] | Emerging Markets Companies Equity Securities [Member] |  |  |  |  |
Actual Allocation by Plan Asset (Details) [Abstract] |  |  |  |  |
Percentage of trust assets |  |  |  | 0.00% | 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 |  |  |  | $ 32 | $ 44
Pension Plan [Member] | U.K. [Member] | Global Equities Equity Securities [Member] |  |  |  |  |
Actual Allocation by Plan Asset (Details) [Abstract] |  |  |  |  |
Percentage of trust assets |  |  |  | 19.00% | 19.00%
Target Allocations (Details ) [Abstract] |  |  |  |  |
Target asset allocation |  |  |  | 9.00% |
Defined benefit plan fair value of plan assets (Details) [Abstract] |  |  |  |  |
Measured at fair value using net asset value per share |  |  |  | $ 1,684 | $ 1,465
Pension Plan [Member] | U.K. [Member] | Global Tactical Asset Allocation Equity Securities [Member] |  |  |  |  |
Actual Allocation by Plan Asset (Details) [Abstract] |  |  |  |  |
Percentage of trust assets |  |  |  | 29.00% | 31.00%
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 |  |  |  | $ 2,584 | $ 2,437
Pension Plan [Member] | U.K. [Member] | Debt Securities [Member] |  |  |  |  |
Actual Allocation by Plan Asset (Details) [Abstract] |  |  |  |  |
Percentage of trust assets |  |  |  | 43.00% | 38.00%
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 |  |  |  | $ 5 | $ 4
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 |  |  |  | 5 | 4
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 |  |  |  | 3,819 | 2,933
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 |  |  |  | 3,819 | 2,933
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 |  |  |  | 6.00% |
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 |  |  |  | $ 519 | $ 485
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 | 8,982 | 7,772 | 7,772 | 8,982 | 7,772
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 8,982 | 7,772 |  |  |
Balance at end of period |  | 8,982 | 7,772 |  |
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 | (37) | 29 | 29 | $ (37) | $ 29
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | (37) | 29 |  |  |
Balance at end of period |  | (37) | 29 |  |
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 | 340 | 301 | 301 | $ 340 | $ 301
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 340 | 301 | 405 |  |
Balance at end of period |  | 340 | 301 |  |
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract] |  |  |  |  |
Employer contributions |  | 10 | 23 |  |
Amount to be contributed to plan in the next fiscal year |  |  |  | 14 |
Estimated Future Benefit Payments (Details) [Abstract] |  |  |  |  |
2020 |  |  |  | 50 |
2021 |  |  |  | 48 |
2022 |  |  |  | 47 |
2023 |  |  |  | 46 |
2024 |  |  |  | 44 |
2025-2029 |  |  |  | 200 |
Expected Federal Subsidy (Details) [Abstract] |  |  |  |  |
Federal subsidy 2020 |  |  |  | 1 |
Federal subsidy 2021 |  |  |  | 1 |
Federal subsidy 2022 |  |  |  | 0 |
Federal subsidy 2023 |  |  |  | 0 |
Federal subsidy 2024 |  |  |  | 0 |
Federal subsidy 2025-2029 |  |  |  | 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 | 6 | 6 | 6 | 6
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 6 | 6 |  |  |
Balance at end of period |  | 6 | 6 |  |
Other Postretirement Benefits Plan [Member] | Level 2 [Member] |  |  |  |  |
Defined benefit plan fair value of plan assets (Details) [Abstract] |  |  |  |  |
Fair value at end of period | 35 | 28 | 28 | 35 | 28
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 35 | 28 |  |  |
Balance at end of period |  | 35 | 28 |  |
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 |  |  |  | 3.00% | 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] |  |  |  |  |
Measured at fair value not using net asset value per share |  |  |  | $ 6 | $ 6
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 | 6
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 |  |  |  | 45.00% | 40.00%
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 |  |  |  | $ 89 | $ 69
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 | $ 68
Other Postretirement Benefits Plan [Member] | Debt Securities [Member] |  |  |  |  |
Actual Allocation by Plan Asset (Details) [Abstract] |  |  |  |  |
Percentage of trust assets |  |  |  | 52.00% | 56.00%
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] |  |  |  |  |
Measured at fair value not using net asset value per share |  |  |  | $ 35 | $ 28
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 |  |  |  | 35 | 28
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 | 198 | $ 171 | 171 | 198 | 171
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 198 | 171 |  |  |
Balance at end of period |  | 198 | 171 |  |
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 | 0 | 1 | 1 | 0 | 1
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 0 | 1 |  |  |
Balance at end of period |  | 0 | 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 | 142 | 129 | 129 | 142 | 129
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 142 | 129 |  |  |
Balance at end of period |  | 142 | 129 |  |
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 | 1,470 | 1,470 | 1,402 | 1,470 | $ 1,294
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 1,470 | 1,294 | 1,402 |  |
Balance at end of period |  | 1,470 | 1,294 |  |
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract] |  |  |  |  |
Employer contributions |  | $ 24 | $ 109 |  |
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 |  |  |  | 5 |
Estimated Future Benefit Payments (Details) [Abstract] |  |  |  |  |
2020 |  |  |  | 114 |
2021 |  |  |  | 115 |
2022 |  |  |  | 115 |
2023 |  |  |  | 113 |
2024 |  |  |  | 115 |
2025-2029 |  |  |  | $ 545 |
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 | 22 |  |  |  |
LG And E And KU Energy LLC [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [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% |
Information About Plan Assets (Numeric) [Abstract] |  |  |  |  |
Value of plan U.S. pension trust assets that relate to PPL subsidiary |  |  |  | $ 1,500 | $ 1,300
Undivided interest percentage in each asset category that PPL subsidiary holds |  | 41.00% | 42.00% |  |
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 |  |  |  | 63 |
Number Of Days Notice Required To Redeem Shares |  | 45 days |  |  |
Defined benefit plan fair value of plan assets (Details) [Abstract] |  |  |  |  |
Fair value at end of period | 3,585 | $ 3,585 | $ 3,109 | 3,585 | 3,109
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 3,585 | 3,109 |  |  |
Balance at end of period |  | 3,585 | 3,109 |  |
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 | 685 | 685 | 591 | 685 | 591
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 685 | 591 |  |  |
Balance at end of period |  | 685 | 591 |  |
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 | 949 | 949 | 924 | 949 | 924
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 949 | 924 |  |  |
Balance at end of period |  | 949 | 924 |  |
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 | 24 | 24 | 46 | 24 | 46
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 24 | 46 | 37 |  |
Actual return on plan assets relating to assets still held at the reporting date |  | 3 | (1) |  |
Actual return on plan assets relating to assets sold during the period |  | 3 |  |  |
Purchases, sales and settlements |  | (28) | 7 |  |
Balance at end of period |  | 24 | 46 |  |
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 |  |  |  | 182 | 220
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 |  |  |  | 182 | 220
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 |  |  |  | 451 | 340
Measured at fair value not using net asset value per share |  |  |  | 194 | 159
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 |  |  |  | 194 | 159
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 |  |  |  | 554 | 466
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 |  |  |  | 621 | 543
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 |  |  |  | 310 | 212
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 |  |  |  | 309 | 212
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 |  |  |  | 1 | 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 |  |  |  | 951 | 899
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 |  |  |  | 931 | 874
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 |  |  |  | 20 | 25
Fair value at end of period | 20 | 20 | 25 | 20 | 25
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 20 | 25 | 13 |  |
Actual return on plan assets relating to assets still held at the reporting date |  | (1) | (2) |  |
Actual return on plan assets relating to assets sold during the period |  | 3 |  |  |
Purchases, sales and settlements |  | (7) | 11 |  |
Balance at end of period |  | 20 | 25 |  |
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 |  |  |  | 14 | 17
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 |  |  |  | 14 | 17
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 |  |  |  | 88 | 90
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 | 3,628 | 3,628 | 3,240 | 3,628 | 3,240
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 3,628 | 3,240 |  |  |
Balance at end of period |  | 3,628 | 3,240 |  |
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 |  |  |  | 62 | 65
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 |  |  |  | 194 | 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 |  |  |  | 3 | 33
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 |  |  |  | 3 | 33
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 |  |  |  | 4 | 21
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 |  |  |  | 4 | 21
Fair value at end of period | 4 | 4 | 21 | 4 | 21
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 4 | 21 | 24 |  |
Actual return on plan assets relating to assets still held at the reporting date |  | 4 | 1 |  |
Actual return on plan assets relating to assets sold during the period |  | 0 |  |  |
Purchases, sales and settlements |  | (21) | (4) |  |
Balance at end of period |  | 4 | 21 |  |
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 | 99 | 99 | (2) | 99 | (2)
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 99 | (2) |  |  |
Balance at end of period |  | 99 | (2) |  |
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 | (142) | (142) | (129) | $ (142) | $ (129)
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | (142) | (129) |  |  |
Balance at end of period |  | (142) | (129) |  |
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 |  |  |  | 57.00% | 55.00%
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 |  |  |  | 34.00% | 30.00%
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 |  |  |  | 14.00% | 15.00%
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 |  |  |  | 9.00% | 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 |  |  |  | 42.00% | 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 |  |  |  | 35.00% | 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 |  |  |  | 7.00% | 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 |  |  |  | 1.00% | 2.00%
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 | 141 | 141 | 116 | $ 141 | $ 117
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 141 | 117 | 116 |  |
Balance at end of period |  | 141 | 117 |  |
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract] |  |  |  |  |
Employer contributions |  | 11 | 24 |  |
Amount to be contributed to plan in the next fiscal year |  |  |  | 14 |
Estimated Future Benefit Payments (Details) [Abstract] |  |  |  |  |
2020 |  |  |  | 14 |
2021 |  |  |  | 15 |
2022 |  |  |  | 15 |
2023 |  |  |  | 15 |
2024 |  |  |  | 15 |
2025-2029 |  |  |  | 72 |
Expected Federal Subsidy (Details) [Abstract] |  |  |  |  |
Federal subsidy 2020 |  |  |  | 1 |
Federal subsidy 2021 |  |  |  | 0 |
Federal subsidy 2022 |  |  |  | 0 |
Federal subsidy 2023 |  |  |  | 0 |
Federal subsidy 2024 |  |  |  | 0 |
Federal subsidy 2025-2029 |  |  |  | 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 | 310 | 281 | 281 | $ 310 | $ 281
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 310 | 281 | 325 |  |
Balance at end of period |  | 310 | 281 |  |
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract] |  |  |  |  |
Employer contributions |  | $ 1 | $ 10 |  |
Louisville Gas And Electric Co [Member] | Pension Plan [Member] | U.S. [Member] | Master Trust [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% |
Information About Plan Assets (Numeric) [Abstract] |  |  |  |  |
Value of plan U.S. pension trust assets that relate to PPL subsidiary |  |  |  | $ 310 | $ 281
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 |  |  |  | 63 |
Number Of Days Notice Required To Redeem Shares |  | 45 days |  |  |
Defined benefit plan fair value of plan assets (Details) [Abstract] |  |  |  |  |
Fair value at end of period | 3,585 | $ 3,585 | $ 3,109 | 3,585 | 3,109
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 3,585 | 3,109 |  |  |
Balance at end of period |  | 3,585 | 3,109 |  |
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 | 685 | 685 | 591 | 685 | 591
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 685 | 591 |  |  |
Balance at end of period |  | 685 | 591 |  |
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 | 949 | 949 | 924 | 949 | 924
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 949 | 924 |  |  |
Balance at end of period |  | 949 | 924 |  |
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 | 24 | 24 | 46 | 24 | 46
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 24 | 46 | 37 |  |
Actual return on plan assets relating to assets still held at the reporting date |  | 3 | (1) |  |
Actual return on plan assets relating to assets sold during the period |  | 3 |  |  |
Purchases, sales and settlements |  | (28) | 7 |  |
Balance at end of period |  | 24 | 46 |  |
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 |  |  |  | 182 | 220
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 |  |  |  | 182 | 220
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 |  |  |  | 451 | 340
Measured at fair value not using net asset value per share |  |  |  | 194 | 159
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 |  |  |  | 194 | 159
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 |  |  |  | 554 | 466
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 |  |  |  | 621 | 543
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 |  |  |  | 310 | 212
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 |  |  |  | 309 | 212
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 |  |  |  | 1 | 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 |  |  |  | 951 | 899
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 |  |  |  | 931 | 874
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 |  |  |  | 20 | 25
Fair value at end of period | 20 | 20 | 25 | 20 | 25
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 20 | 25 | 13 |  |
Actual return on plan assets relating to assets still held at the reporting date |  | (1) | (2) |  |
Actual return on plan assets relating to assets sold during the period |  | 3 |  |  |
Purchases, sales and settlements |  | (7) | 11 |  |
Balance at end of period |  | 20 | 25 |  |
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 |  |  |  | 14 | 17
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 |  |  |  | 14 | 17
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 |  |  |  | 88 | 90
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 | 3,628 | 3,628 | 3,240 | 3,628 | 3,240
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 3,628 | 3,240 |  |  |
Balance at end of period |  | 3,628 | 3,240 |  |
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 |  |  |  | 62 | 65
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 |  |  |  | 194 | 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 |  |  |  | 3 | 33
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 |  |  |  | 3 | 33
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 |  |  |  | 4 | 21
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 |  |  |  | 4 | 21
Fair value at end of period | 4 | 4 | 21 | 4 | 21
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 4 | 21 | 24 |  |
Actual return on plan assets relating to assets still held at the reporting date |  | 4 | 1 |  |
Actual return on plan assets relating to assets sold during the period |  | 0 |  |  |
Purchases, sales and settlements |  | (21) | (4) |  |
Balance at end of period |  | 4 | 21 |  |
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 | 99 | 99 | (2) | 99 | (2)
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | 99 | (2) |  |  |
Balance at end of period |  | 99 | (2) |  |
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 | (142) | (142) | (129) | $ (142) | $ (129)
Change in Fair Value of Level 3 Plan Assets [Roll Forward] |  |  |  |  |
Balance at beginning of period | $ (142) | (129) |  |  |
Balance at end of period |  | $ (142) | $ (129) |  |
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 |  |  |  | 57.00% | 55.00%
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 |  |  |  | 34.00% | 30.00%
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 |  |  |  | 14.00% | 15.00%
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 |  |  |  | 9.00% | 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 |  |  |  | 42.00% | 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 |  |  |  | 35.00% | 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 |  |  |  | 7.00% | 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 |  |  |  | 1.00% | 2.00%
Target Allocations (Details ) [Abstract] |  |  |  |  |
Target asset allocation |  |  |  | 2.00% |

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