New Accounting Guidance Pending Adoption	12 Months Ended
Dec. 31, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Guidance Pending Adoption	21. New Accounting Guidance Pending Adoption (All Registrants) Accounting for Revenue from Contracts with Customers In May 2014, the Financial Accounting Standards Board (FASB) issued accounting guidance that establishes a comprehensive new model for the recognition of revenue from contracts with customers. This model is based on the core principle that revenue should be recognized to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The Registrants have completed an assessment of their revenue under this new guidance and have determined it will not have a material impact on their current revenue recognition policies. The Registrants' operating revenues are derived primarily from tariff-based sales that result from providing electricity and natural gas to customers with no defined contractual term. Tariff-based sales are within the scope of the new guidance, and operating revenues under the new guidance will be equivalent to the electricity and natural gas delivered and billed in that period (including estimated billings), which is consistent with current practice. The disclosure requirements included in the standard will result in increased information being provided to enable the users of the financial statements to understand the nature, amount, timing and uncertainty of revenue arising from contracts with customers. The Registrants will include disaggregation of revenues by geographic location, customer class or type of service, as applicable. Some revenue arrangements, including alternative revenue programs and lease income, are excluded from the scope of the new guidance and will be accounted for and disclosed separately from revenues from contracts with customers. The Registrants will also disclose the opening and closing balances of accounts receivable and any contract assets or contract liabilities resulting from contracts with customers. The Registrants adopted this guidance effective January 1, 2018 using the modified retrospective transition method. Accounting for Leases In February 2016, the FASB issued accounting guidance for leases. This new guidance requires lessees to recognize a right-of-use asset and a lease liability for virtually all of their leases (other than leases that meet the definition of a short-term lease). For income statement purposes, the FASB retained a dual model for lessees, requiring leases to be classified as either operating or finance. Operating leases will result in straight-line expense (similar to current operating leases) while finance leases will result in a front-loaded expense pattern (similar to current capital leases). Classification will be based on criteria that are largely similar to those applied in current lease accounting, but without explicit bright line tests. Lessor accounting under the new guidance is similar to the current model, but updated to align with certain changes to the lessee model and the new revenue recognition standard. Similar to current practice, lessors will classify leases as operating, direct financing, or sales-type. The standard is effective for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted. The new standard must be adopted using a modified retrospective transition, and provides for certain practical expedients. One of these practical expedients allows entities to elect to not evaluate land easements as leases that exist or expired before the adoption date and were not previously accounted for as leases under current lease guidance. Transition will require application of the new guidance at the beginning of the earliest comparative period presented. The Registrants are currently assessing the impact of adopting this guidance. The Registrants will adopt this guidance effective January 1, 2019. Accounting for Financial Instrument Credit Losses In June 2016, the FASB issued accounting guidance that requires the use of a current expected credit loss (CECL) model for the measurement of credit losses on financial instruments within the scope of this guidance, which includes accounts receivable. The CECL model requires an entity to measure credit losses using historical information, current information and reasonable and supportable forecasts of future events, rather than the incurred loss impairment model required under current GAAP. For public business entities, this guidance will be applied using a modified retrospective approach and is effective for fiscal years beginning after December 15, 2019, and interim periods within those years. All entities may early adopt this guidance beginning after December 15, 2018, including interim periods within those years. The Registrants are currently assessing the impact of adopting this guidance and the period they will adopt it. Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost In March 2017, the FASB issued accounting guidance that changes the income statement presentation of net periodic benefit cost. This new guidance requires the service cost component to be disaggregated from other components of net benefit cost and presented in the same income statement line items as other employee compensation costs arising from services rendered during the period. The other components of net periodic benefits will be presented separately from the line items that include the service cost and outside of any subtotal of operating income. Only the service cost component is eligible for capitalization. For public business entities, the guidance on the presentation of the components of net periodic benefit costs will be applied retrospectively. The guidance that limits the capitalization to the service cost component of net periodic benefit costs will be applied prospectively. This guidance is effective for fiscal years beginning after December 15, 2017 and interim periods within those years. The Registrants adopted this guidance effective January 1, 2018. For PPL’s, LKE’s and LG&E’s U.S. defined benefit pension and PPL's and LKE's other postretirement benefit plans, the adoption of this new guidance is not expected to have a material impact on either the presentation on the income statements or the amounts capitalized and related impact to expense, as the difference between the service cost and the non-service cost components of net periodic benefit costs has not historically been and is not expected to be material in 2018. For PPL’s U.K. defined benefit pension plans, the non-service cost components of net periodic benefit cost has been in a net-credit position for the current reporting periods and is expected to continue to be in a net-credit position for 2018. Therefore, the estimated impact of adopting this new guidance related to the non-service cost component credits to be reclassified from “Other operation and maintenance” to “Other Income (Expense)-net” on the Statements of Income is approximately $175 million and $120 million for the years ended 2017 and 2016. The Registrants are finalizing the expected 2018 impacts of adopting the guidance as the amounts are affected by market conditions and assumptions selected at December 31, 2017. Improvements to Accounting for Hedging Activities In August 2017, the FASB issued accounting guidance that reduces complexity when applying hedge accounting as well as improves transparency about an entity's risk management activities. This guidance eliminates recognizing hedge ineffectiveness for cash flow and net investment hedges and provides for the ability to perform subsequent effectiveness assessments qualitatively. The guidance also makes certain changes to allowable methodologies such as allowing entities to apply the short-cut method to partial-term fair value hedges of interest rate risk as well as expands the ability to apply the critical terms match method to cash flow hedges of groups of forecasted transactions. The guidance also updates certain recognition and presentation requirements as well as disclosure requirements. For public business entities, this guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted. This standard must be adopted using a modified retrospective approach and provides for certain transition elections that must be made prior to the first effectiveness testing date after adoption. The Registrants are currently assessing the impact of adopting this guidance and the period they will adopt it. (PPL, LKE, LG&E and KU) Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued accounting guidance that simplifies the test for goodwill impairment by eliminating the second step of the quantitative test. The second step of the quantitative test requires a calculation of the implied fair value of goodwill, which is determined in the same manner as the amount of goodwill in a business combination. Under this new guidance, an entity will now compare the estimated fair value of a reporting unit with its carrying value and recognize an impairment charge for the amount the carrying amount exceeds the fair value of the reporting unit. For public business entities, this guidance will be applied prospectively and is effective for annual or any interim goodwill impairment tests for fiscal years beginning after December 15, 2019. All entities may early adopt this guidance for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Registrants are currently assessing the impact of adopting this guidance and the period they will adopt it. (PPL and LKE) Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In February 2018, the FASB issued accounting guidance that gives entities the option to reclassify tax effects stranded within AOCI as a result of the TCJA to retained earnings. The reclassification applies only to those stranded tax effects arising from the TCJA enactment. Certain disclosures related to the stranded tax effects, including a description of the accounting policy for releasing income tax effects from AOCI, are required. For all entities, this guidance is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. Early adoption is permitted, including adoption in any interim period. The amendments should be applied either in the period of adoption or retrospectively to each period in which the effect of the change in the U.S. federal corporate income tax rate in the TCJA is recognized. The Registrants are currently assessing this guidance and the period in which they will adopt it.

21. New Accounting Guidance Pending Adoption

(All Registrants)

Accounting for Revenue from Contracts with Customers

In May 2014, the Financial Accounting Standards Board (FASB) issued accounting guidance that establishes a comprehensive new model for the recognition of revenue from contracts with customers. This model is based on the core principle that revenue should be recognized to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services.

The Registrants have completed an assessment of their revenue under this new guidance and have determined it will not have a material impact on their current revenue recognition policies. The Registrants' operating revenues are derived primarily from tariff-based sales that result from providing electricity and natural gas to customers with no defined contractual term. Tariff-based sales are within the scope of the new guidance, and operating revenues under the new guidance will be equivalent to the electricity and natural gas delivered and billed in that period (including estimated billings), which is consistent with current practice.

The disclosure requirements included in the standard will result in increased information being provided to enable the users of the financial statements to understand the nature, amount, timing and uncertainty of revenue arising from contracts with customers. The Registrants will include disaggregation of revenues by geographic location, customer class or type of service, as applicable. Some revenue arrangements, including alternative revenue programs and lease income, are excluded from the scope of the new guidance and will be accounted for and disclosed separately from revenues from contracts with customers. The Registrants will also disclose the opening and closing balances of accounts receivable and any contract assets or contract liabilities resulting from contracts with customers.

The Registrants adopted this guidance effective January 1, 2018 using the modified retrospective transition method.

Accounting for Leases

In February 2016, the FASB issued accounting guidance for leases. This new guidance requires lessees to recognize a right-of-use asset and a lease liability for virtually all of their leases (other than leases that meet the definition of a short-term lease). For income statement purposes, the FASB retained a dual model for lessees, requiring leases to be classified as either operating or finance. Operating leases will result in straight-line expense (similar to current operating leases) while finance leases will result in a front-loaded expense pattern (similar to current capital leases). Classification will be based on criteria that are largely similar to those applied in current lease accounting, but without explicit bright line tests.

Lessor accounting under the new guidance is similar to the current model, but updated to align with certain changes to the lessee model and the new revenue recognition standard. Similar to current practice, lessors will classify leases as operating, direct financing, or sales-type.

The standard is effective for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted. The new standard must be adopted using a modified retrospective transition, and provides for certain practical expedients. One of these practical expedients allows entities to elect to not evaluate land easements as leases that exist or expired before the adoption date and were not previously accounted for as leases under current lease guidance. Transition will require application of the new guidance at the beginning of the earliest comparative period presented.

The Registrants are currently assessing the impact of adopting this guidance. The Registrants will adopt this guidance effective January 1, 2019.

Accounting for Financial Instrument Credit Losses

In June 2016, the FASB issued accounting guidance that requires the use of a current expected credit loss (CECL) model for the measurement of credit losses on financial instruments within the scope of this guidance, which includes accounts receivable. The CECL model requires an entity to measure credit losses using historical information, current information and reasonable and supportable forecasts of future events, rather than the incurred loss impairment model required under current GAAP.

For public business entities, this guidance will be applied using a modified retrospective approach and is effective for fiscal years beginning after December 15, 2019, and interim periods within those years. All entities may early adopt this guidance beginning after December 15, 2018, including interim periods within those years.

The Registrants are currently assessing the impact of adopting this guidance and the period they will adopt it.

Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost

In March 2017, the FASB issued accounting guidance that changes the income statement presentation of net periodic benefit cost. This new guidance requires the service cost component to be disaggregated from other components of net benefit cost and presented in the same income statement line items as other employee compensation costs arising from services rendered during the period. The other components of net periodic benefits will be presented separately from the line items that include the service cost and outside of any subtotal of operating income. Only the service cost component is eligible for capitalization.

For public business entities, the guidance on the presentation of the components of net periodic benefit costs will be applied retrospectively. The guidance that limits the capitalization to the service cost component of net periodic benefit costs will be applied prospectively. This guidance is effective for fiscal years beginning after December 15, 2017 and interim periods within those years. The Registrants adopted this guidance effective January 1, 2018.

For PPL’s, LKE’s and LG&E’s U.S. defined benefit pension and PPL's and LKE's other postretirement benefit plans, the adoption of this new guidance is not expected to have a material impact on either the presentation on the income statements or the amounts capitalized and related impact to expense, as the difference between the service cost and the non-service cost components of net periodic benefit costs has not historically been and is not expected to be material in 2018.

For PPL’s U.K. defined benefit pension plans, the non-service cost components of net periodic benefit cost has been in a net-credit position for the current reporting periods and is expected to continue to be in a net-credit position for 2018. Therefore, the estimated impact of adopting this new guidance related to the non-service cost component credits to be reclassified from “Other operation and maintenance” to “Other Income (Expense)-net” on the Statements of Income is approximately $175 million and $120 million for the years ended 2017 and 2016.

The Registrants are finalizing the expected 2018 impacts of adopting the guidance as the amounts are affected by market conditions and assumptions selected at December 31, 2017.

Improvements to Accounting for Hedging Activities

In August 2017, the FASB issued accounting guidance that reduces complexity when applying hedge accounting as well as improves transparency about an entity's risk management activities. This guidance eliminates recognizing hedge ineffectiveness for cash flow and net investment hedges and provides for the ability to perform subsequent effectiveness assessments qualitatively. The guidance also makes certain changes to allowable methodologies such as allowing entities to apply the short-cut method to partial-term fair value hedges of interest rate risk as well as expands the ability to apply the critical terms match method to cash flow hedges of groups of forecasted transactions. The guidance also updates certain recognition and presentation requirements as well as disclosure requirements.

For public business entities, this guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted. This standard must be adopted using a modified retrospective approach and provides for certain transition elections that must be made prior to the first effectiveness testing date after adoption.

The Registrants are currently assessing the impact of adopting this guidance and the period they will adopt it.

(PPL, LKE, LG&E and KU)

Simplifying the Test for Goodwill Impairment

In January 2017, the FASB issued accounting guidance that simplifies the test for goodwill impairment by eliminating the second step of the quantitative test. The second step of the quantitative test requires a calculation of the implied fair value of goodwill, which is determined in the same manner as the amount of goodwill in a business combination. Under this new guidance, an entity will now compare the estimated fair value of a reporting unit with its carrying value and recognize an impairment charge for the amount the carrying amount exceeds the fair value of the reporting unit.

For public business entities, this guidance will be applied prospectively and is effective for annual or any interim goodwill impairment tests for fiscal years beginning after December 15, 2019. All entities may early adopt this guidance for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017.

The Registrants are currently assessing the impact of adopting this guidance and the period they will adopt it.

(PPL and LKE)

Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income

In February 2018, the FASB issued accounting guidance that gives entities the option to reclassify tax effects stranded within AOCI as a result of the TCJA to retained earnings. The reclassification applies only to those stranded tax effects arising from the TCJA enactment. Certain disclosures related to the stranded tax effects, including a description of the accounting policy for releasing income tax effects from AOCI, are required.

For all entities, this guidance is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. Early adoption is permitted, including adoption in any interim period. The amendments should be applied either in the period of adoption or retrospectively to each period in which the effect of the change in the U.S. federal corporate income tax rate in the TCJA is recognized.

The Registrants are currently assessing this guidance and the period in which they will adopt it.