XML 57 R24.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Commitments And Contingencies | 12 Months Ended
--- | ---
Dec. 31, 2018
Commitments And Contingencies | COMMITMENTS AND CONTINGENCIES (a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects. IPL’s projects include the expansion of wind generation. WPL’s projects include West Riverside. At December 31, 2018, Alliant Energy’s, IPL’s and WPL’s minimum future commitments for these projects were $40 million, $14 million and $26 million, respectively. (b) Other Purchase Commitments - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. In addition, there are various purchase commitments associated with other goods and services. At December 31, 2018, the related minimum future commitments were as follows (in millions):
Alliant Energy | 2019 |  | 2020 |  | 2021 |  | 2022 |  | 2023 |  | Thereafter |  | Total
Purchased power (a) |  | $159 |  |  |  | $135 |  |  |  | $149 |  |  |  | $140 |  |  |  | $155 |  |  |  | $307 |  |  |  | $1,045 |
Natural gas | 254 |  |  | 151 |  |  | 119 |  |  | 94 |  |  | 67 |  |  | 196 |  |  | 881 |
Coal (b) | 102 |  |  | 49 |  |  | 26 |  |  | 9 |  |  | 9 |  |  | — |  |  | 195 |
Other (c) | 60 |  |  | 4 |  |  | 3 |  |  | 2 |  |  | 2 |  |  | — |  |  | 71 |
|  | $575 |  |  |  | $339 |  |  |  | $297 |  |  |  | $245 |  |  |  | $233 |  |  |  | $503 |  |  |  | $2,192 |
IPL | 2019 |  | 2020 |  | 2021 |  | 2022 |  | 2023 |  | Thereafter |  | Total
Purchased power (a) |  | $144 |  |  |  | $135 |  |  |  | $149 |  |  |  | $140 |  |  |  | $155 |  |  |  | $307 |  |  |  | $1,030 |
Natural gas | 124 |  |  | 55 |  |  | 42 |  |  | 33 |  |  | 26 |  |  | 83 |  |  | 363 |
Coal (b) | 52 |  |  | 29 |  |  | 20 |  |  | 9 |  |  | 9 |  |  | — |  |  | 119 |
Other (c) | 24 |  |  | 3 |  |  | 3 |  |  | 2 |  |  | 2 |  |  | — |  |  | 34 |
|  | $344 |  |  |  | $222 |  |  |  | $214 |  |  |  | $184 |  |  |  | $192 |  |  |  | $390 |  |  |  | $1,546 |
WPL | 2019 |  | 2020 |  | 2021 |  | 2022 |  | 2023 |  | Thereafter |  | Total
Purchased power |  | $15 |  |  |  | $— |  |  |  | $— |  |  |  | $— |  |  |  | $— |  |  |  | $— |  |  |  | $15 |
Natural gas | 130 |  |  | 96 |  |  | 77 |  |  | 61 |  |  | 41 |  |  | 113 |  |  | 518 |
Coal (b) | 50 |  |  | 20 |  |  | 6 |  |  | — |  |  | — |  |  | — |  |  | 76 |
Other (c) | 23 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 23 |
|  | $218 |  |  |  | $116 |  |  |  | $83 |  |  |  | $61 |  |  |  | $41 |  |  |  | $113 |  |  |  | $632 |
(a) | Includes payments required by PPAs for capacity rights and minimum quantities of MWhs required to be purchased. In July 2018, IPL entered into an amendment to shorten the term of the DAEC PPA by five years in exchange for a $110 million buyout payment by IPL in September 2020, subject to IUB approval. In December 2018, IPL received an order from the IUB, which was effective in January 2019, approving recovery of the buyout payment. As a result, Alliant Energy’s and IPL’s amounts in the above table do not include the September 2020 buyout payment, and the minimum future commitments reflect IPL’s purchase of capacity and the resulting energy from DAEC through December 2025, the original term of the PPA prior to the amendment. Amounts in the above table for 2021 and beyond relate to the DAEC PPA.
(b) | Corporate Services entered into system-wide coal contracts on behalf of IPL and WPL that include minimum future commitments. These commitments were assigned to IPL and WPL based on information available as of December 31, 2018 regarding expected future usage, which is subject to change.
(c) | Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2018.
(c) Legal Proceedings - Alliant Energy, IPL and WPL are involved in legal and administrative proceedings before various courts and agencies with respect to matters arising in the ordinary course of business. Although unable to predict the outcome of these matters, Alliant Energy, IPL and WPL believe that appropriate reserves have been established and final disposition of these actions will not have a material effect on their financial condition or results of operations. (d) Guarantees and Indemnifications - Whiting Petroleum - In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum. Whiting Petroleum is an independent oil and gas company. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, continues to guarantee the partnership obligations of an affiliate of Whiting Petroleum under general partnership agreements in the oil and gas industry, including with respect to the future abandonment of certain platforms off the coast of California and related onshore plant and equipment owned by the partnerships. The guarantees do not include a maximum limit. As of December 31, 2018, the present value of the abandonment obligations is estimated at $36 million. Alliant Energy is not aware of any material liabilities related to these guarantees of which it is probable that Alliant Energy Resources, LLC will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of December 31, 2018 and 2017. Non-utility Wind Farm in Oklahoma - In July 2017, a wholly-owned subsidiary of AEF acquired a cash equity ownership interest in a non-utility wind farm located in Oklahoma. The wind farm provides electricity to a third-party under a long-term PPA. Alliant Energy provided a parent guarantee of its subsidiary’s indemnification obligations under the related operating agreement and PPA. Alliant Energy’s obligations under the operating agreement were $90 million as of December 31, 2018 and will reduce annually until expiring in July 2047. Alliant Energy’s obligations under the PPA are subject to a maximum limit of $17 million and expire in December 2031, subject to potential extension. Alliant Energy is not aware of any material liabilities related to this guarantee that it is probable that it will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of December 31, 2018 and 2017. IPL’s Minnesota Electric Distribution Assets - IPL provided indemnifications associated with the July 2015 sale of its Minnesota electric distribution assets for losses resulting from potential breach of IPL’s representations, warranties and obligations under the sale agreement. Alliant Energy and IPL believe the likelihood of having to make any material cash payments under these indemnifications is remote. IPL has not recorded any material liabilities related to these indemnifications as of December 31, 2018 and 2017. The general terms of the indemnifications provided by IPL included a maximum limit of $17 million and expire in October 2020. (e) Environmental Matters - Alliant Energy, IPL and WPL are subject to environmental regulations as a result of their current and past operations. These regulations are designed to protect public health and the environment and have resulted in compliance, remediation, containment and monitoring obligations, which are recorded as current and non-current environmental liabilities. Substantially all of the environmental liabilities recorded on the balance sheets relate to MGP sites. MGP Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. At December 31, 2018, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions). At December 31, 2018, such amounts for WPL were not material.
| Alliant Energy |  | IPL
Range of estimated future costs |  | $11 |  | - | $29 |  |  | $8 |  | - | $24
Current and non-current environmental liabilities | 15 |  | 12
IPL Consent Decree - In 2015, the U.S. District Court for the Northern District of Iowa approved a Consent Decree that IPL entered into with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa, thereby resolving potential CAA issues associated with emissions from IPL’s coal-fired generating facilities in Iowa. IPL has completed various requirements under the Consent Decree. IPL’s remaining requirements include installing an SCR system or equivalent NOx reduction system at Ottumwa by December 31, 2019, and fuel switching or retiring Burlington by December 31, 2021 and Prairie Creek Units 1 and 3 by December 31, 2025. Alliant Energy and IPL currently expect to recover material costs incurred by IPL related to compliance with the terms of the Consent Decree from IPL’s electric customers. Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however future capital investments and/or modifications to EGUs to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters include, among others: Effluent Limitation Guidelines, CCR Rule, and various legislation and EPA regulations to monitor and regulate the emission of GHG, including the CAA. (f) Credit Risk - IPL provides retail electric and gas services in Iowa and wholesale electric service in Minnesota, Illinois and Iowa. WPL provides retail electric and gas services and wholesale electric service in Wisconsin. The geographic concentration of IPL’s and WPL’s customers did not contribute significantly to overall credit risk exposure. In addition, as a result of a diverse customer base, IPL and WPL did not have any significant credit risk concentration for receivables arising from the sale of electricity or gas services. Alliant Energy, IPL and WPL are subject to credit risk related to the ability of counterparties to meet their contractual payment obligations or the potential non-performance of counterparties to deliver contracted commodities and other goods or services at the contracted price. Credit policies are maintained to mitigate credit risk. These credit policies include evaluation of the financial condition of certain counterparties, use of credit risk-related contingent provisions in certain agreements that require credit support from counterparties not meeting specific criteria, diversification of counterparties to reduce concentrations of credit risk and the use of standardized agreements that facilitate the netting of cash flows associated with certain counterparties. Based on these credit policies and counterparty diversification, as well as utility cost recovery mechanisms, it is unlikely that counterparty non-performance would have a material effect on financial condition or results of operations. However, there is no assurance that these items will protect against all losses from counterparty non-performance. Refer to Notes 5(a) and 15 for details of allowances for doubtful accounts and credit risk-related contingent features, respectively. (g) Collective Bargaining Agreements - At December 31, 2018, employees covered by collective bargaining agreements represented 55%, 63% and 82% of total employees of Alliant Energy, IPL and WPL, respectively. In May 2019, WPL’s collective bargaining agreement with International Brotherhood of Electrical Workers Local 965 expires, representing 26% and 82% of total employees of Alliant Energy and WPL, respectively.
IPL [Member] |
Commitments And Contingencies | COMMITMENTS AND CONTINGENCIES (a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects. IPL’s projects include the expansion of wind generation. WPL’s projects include West Riverside. At December 31, 2018, Alliant Energy’s, IPL’s and WPL’s minimum future commitments for these projects were $40 million, $14 million and $26 million, respectively. (b) Other Purchase Commitments - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. In addition, there are various purchase commitments associated with other goods and services. At December 31, 2018, the related minimum future commitments were as follows (in millions):
Alliant Energy | 2019 |  | 2020 |  | 2021 |  | 2022 |  | 2023 |  | Thereafter |  | Total
Purchased power (a) |  | $159 |  |  |  | $135 |  |  |  | $149 |  |  |  | $140 |  |  |  | $155 |  |  |  | $307 |  |  |  | $1,045 |
Natural gas | 254 |  |  | 151 |  |  | 119 |  |  | 94 |  |  | 67 |  |  | 196 |  |  | 881 |
Coal (b) | 102 |  |  | 49 |  |  | 26 |  |  | 9 |  |  | 9 |  |  | — |  |  | 195 |
Other (c) | 60 |  |  | 4 |  |  | 3 |  |  | 2 |  |  | 2 |  |  | — |  |  | 71 |
|  | $575 |  |  |  | $339 |  |  |  | $297 |  |  |  | $245 |  |  |  | $233 |  |  |  | $503 |  |  |  | $2,192 |
IPL | 2019 |  | 2020 |  | 2021 |  | 2022 |  | 2023 |  | Thereafter |  | Total
Purchased power (a) |  | $144 |  |  |  | $135 |  |  |  | $149 |  |  |  | $140 |  |  |  | $155 |  |  |  | $307 |  |  |  | $1,030 |
Natural gas | 124 |  |  | 55 |  |  | 42 |  |  | 33 |  |  | 26 |  |  | 83 |  |  | 363 |
Coal (b) | 52 |  |  | 29 |  |  | 20 |  |  | 9 |  |  | 9 |  |  | — |  |  | 119 |
Other (c) | 24 |  |  | 3 |  |  | 3 |  |  | 2 |  |  | 2 |  |  | — |  |  | 34 |
|  | $344 |  |  |  | $222 |  |  |  | $214 |  |  |  | $184 |  |  |  | $192 |  |  |  | $390 |  |  |  | $1,546 |
WPL | 2019 |  | 2020 |  | 2021 |  | 2022 |  | 2023 |  | Thereafter |  | Total
Purchased power |  | $15 |  |  |  | $— |  |  |  | $— |  |  |  | $— |  |  |  | $— |  |  |  | $— |  |  |  | $15 |
Natural gas | 130 |  |  | 96 |  |  | 77 |  |  | 61 |  |  | 41 |  |  | 113 |  |  | 518 |
Coal (b) | 50 |  |  | 20 |  |  | 6 |  |  | — |  |  | — |  |  | — |  |  | 76 |
Other (c) | 23 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 23 |
|  | $218 |  |  |  | $116 |  |  |  | $83 |  |  |  | $61 |  |  |  | $41 |  |  |  | $113 |  |  |  | $632 |
(a) | Includes payments required by PPAs for capacity rights and minimum quantities of MWhs required to be purchased. In July 2018, IPL entered into an amendment to shorten the term of the DAEC PPA by five years in exchange for a $110 million buyout payment by IPL in September 2020, subject to IUB approval. In December 2018, IPL received an order from the IUB, which was effective in January 2019, approving recovery of the buyout payment. As a result, Alliant Energy’s and IPL’s amounts in the above table do not include the September 2020 buyout payment, and the minimum future commitments reflect IPL’s purchase of capacity and the resulting energy from DAEC through December 2025, the original term of the PPA prior to the amendment. Amounts in the above table for 2021 and beyond relate to the DAEC PPA.
(b) | Corporate Services entered into system-wide coal contracts on behalf of IPL and WPL that include minimum future commitments. These commitments were assigned to IPL and WPL based on information available as of December 31, 2018 regarding expected future usage, which is subject to change.
(c) | Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2018.
(c) Legal Proceedings - Alliant Energy, IPL and WPL are involved in legal and administrative proceedings before various courts and agencies with respect to matters arising in the ordinary course of business. Although unable to predict the outcome of these matters, Alliant Energy, IPL and WPL believe that appropriate reserves have been established and final disposition of these actions will not have a material effect on their financial condition or results of operations. (d) Guarantees and Indemnifications - Whiting Petroleum - In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum. Whiting Petroleum is an independent oil and gas company. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, continues to guarantee the partnership obligations of an affiliate of Whiting Petroleum under general partnership agreements in the oil and gas industry, including with respect to the future abandonment of certain platforms off the coast of California and related onshore plant and equipment owned by the partnerships. The guarantees do not include a maximum limit. As of December 31, 2018, the present value of the abandonment obligations is estimated at $36 million. Alliant Energy is not aware of any material liabilities related to these guarantees of which it is probable that Alliant Energy Resources, LLC will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of December 31, 2018 and 2017. Non-utility Wind Farm in Oklahoma - In July 2017, a wholly-owned subsidiary of AEF acquired a cash equity ownership interest in a non-utility wind farm located in Oklahoma. The wind farm provides electricity to a third-party under a long-term PPA. Alliant Energy provided a parent guarantee of its subsidiary’s indemnification obligations under the related operating agreement and PPA. Alliant Energy’s obligations under the operating agreement were $90 million as of December 31, 2018 and will reduce annually until expiring in July 2047. Alliant Energy’s obligations under the PPA are subject to a maximum limit of $17 million and expire in December 2031, subject to potential extension. Alliant Energy is not aware of any material liabilities related to this guarantee that it is probable that it will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of December 31, 2018 and 2017. IPL’s Minnesota Electric Distribution Assets - IPL provided indemnifications associated with the July 2015 sale of its Minnesota electric distribution assets for losses resulting from potential breach of IPL’s representations, warranties and obligations under the sale agreement. Alliant Energy and IPL believe the likelihood of having to make any material cash payments under these indemnifications is remote. IPL has not recorded any material liabilities related to these indemnifications as of December 31, 2018 and 2017. The general terms of the indemnifications provided by IPL included a maximum limit of $17 million and expire in October 2020. (e) Environmental Matters - Alliant Energy, IPL and WPL are subject to environmental regulations as a result of their current and past operations. These regulations are designed to protect public health and the environment and have resulted in compliance, remediation, containment and monitoring obligations, which are recorded as current and non-current environmental liabilities. Substantially all of the environmental liabilities recorded on the balance sheets relate to MGP sites. MGP Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. At December 31, 2018, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions). At December 31, 2018, such amounts for WPL were not material.
| Alliant Energy |  | IPL
Range of estimated future costs |  | $11 |  | - | $29 |  |  | $8 |  | - | $24
Current and non-current environmental liabilities | 15 |  | 12
IPL Consent Decree - In 2015, the U.S. District Court for the Northern District of Iowa approved a Consent Decree that IPL entered into with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa, thereby resolving potential CAA issues associated with emissions from IPL’s coal-fired generating facilities in Iowa. IPL has completed various requirements under the Consent Decree. IPL’s remaining requirements include installing an SCR system or equivalent NOx reduction system at Ottumwa by December 31, 2019, and fuel switching or retiring Burlington by December 31, 2021 and Prairie Creek Units 1 and 3 by December 31, 2025. Alliant Energy and IPL currently expect to recover material costs incurred by IPL related to compliance with the terms of the Consent Decree from IPL’s electric customers. Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however future capital investments and/or modifications to EGUs to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters include, among others: Effluent Limitation Guidelines, CCR Rule, and various legislation and EPA regulations to monitor and regulate the emission of GHG, including the CAA. (f) Credit Risk - IPL provides retail electric and gas services in Iowa and wholesale electric service in Minnesota, Illinois and Iowa. WPL provides retail electric and gas services and wholesale electric service in Wisconsin. The geographic concentration of IPL’s and WPL’s customers did not contribute significantly to overall credit risk exposure. In addition, as a result of a diverse customer base, IPL and WPL did not have any significant credit risk concentration for receivables arising from the sale of electricity or gas services. Alliant Energy, IPL and WPL are subject to credit risk related to the ability of counterparties to meet their contractual payment obligations or the potential non-performance of counterparties to deliver contracted commodities and other goods or services at the contracted price. Credit policies are maintained to mitigate credit risk. These credit policies include evaluation of the financial condition of certain counterparties, use of credit risk-related contingent provisions in certain agreements that require credit support from counterparties not meeting specific criteria, diversification of counterparties to reduce concentrations of credit risk and the use of standardized agreements that facilitate the netting of cash flows associated with certain counterparties. Based on these credit policies and counterparty diversification, as well as utility cost recovery mechanisms, it is unlikely that counterparty non-performance would have a material effect on financial condition or results of operations. However, there is no assurance that these items will protect against all losses from counterparty non-performance. Refer to Notes 5(a) and 15 for details of allowances for doubtful accounts and credit risk-related contingent features, respectively. (g) Collective Bargaining Agreements - At December 31, 2018, employees covered by collective bargaining agreements represented 55%, 63% and 82% of total employees of Alliant Energy, IPL and WPL, respectively. In May 2019, WPL’s collective bargaining agreement with International Brotherhood of Electrical Workers Local 965 expires, representing 26% and 82% of total employees of Alliant Energy and WPL, respectively.
WPL [Member] |
Commitments And Contingencies | COMMITMENTS AND CONTINGENCIES (a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects. IPL’s projects include the expansion of wind generation. WPL’s projects include West Riverside. At December 31, 2018, Alliant Energy’s, IPL’s and WPL’s minimum future commitments for these projects were $40 million, $14 million and $26 million, respectively. (b) Other Purchase Commitments - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. In addition, there are various purchase commitments associated with other goods and services. At December 31, 2018, the related minimum future commitments were as follows (in millions):
Alliant Energy | 2019 |  | 2020 |  | 2021 |  | 2022 |  | 2023 |  | Thereafter |  | Total
Purchased power (a) |  | $159 |  |  |  | $135 |  |  |  | $149 |  |  |  | $140 |  |  |  | $155 |  |  |  | $307 |  |  |  | $1,045 |
Natural gas | 254 |  |  | 151 |  |  | 119 |  |  | 94 |  |  | 67 |  |  | 196 |  |  | 881 |
Coal (b) | 102 |  |  | 49 |  |  | 26 |  |  | 9 |  |  | 9 |  |  | — |  |  | 195 |
Other (c) | 60 |  |  | 4 |  |  | 3 |  |  | 2 |  |  | 2 |  |  | — |  |  | 71 |
|  | $575 |  |  |  | $339 |  |  |  | $297 |  |  |  | $245 |  |  |  | $233 |  |  |  | $503 |  |  |  | $2,192 |
IPL | 2019 |  | 2020 |  | 2021 |  | 2022 |  | 2023 |  | Thereafter |  | Total
Purchased power (a) |  | $144 |  |  |  | $135 |  |  |  | $149 |  |  |  | $140 |  |  |  | $155 |  |  |  | $307 |  |  |  | $1,030 |
Natural gas | 124 |  |  | 55 |  |  | 42 |  |  | 33 |  |  | 26 |  |  | 83 |  |  | 363 |
Coal (b) | 52 |  |  | 29 |  |  | 20 |  |  | 9 |  |  | 9 |  |  | — |  |  | 119 |
Other (c) | 24 |  |  | 3 |  |  | 3 |  |  | 2 |  |  | 2 |  |  | — |  |  | 34 |
|  | $344 |  |  |  | $222 |  |  |  | $214 |  |  |  | $184 |  |  |  | $192 |  |  |  | $390 |  |  |  | $1,546 |
WPL | 2019 |  | 2020 |  | 2021 |  | 2022 |  | 2023 |  | Thereafter |  | Total
Purchased power |  | $15 |  |  |  | $— |  |  |  | $— |  |  |  | $— |  |  |  | $— |  |  |  | $— |  |  |  | $15 |
Natural gas | 130 |  |  | 96 |  |  | 77 |  |  | 61 |  |  | 41 |  |  | 113 |  |  | 518 |
Coal (b) | 50 |  |  | 20 |  |  | 6 |  |  | — |  |  | — |  |  | — |  |  | 76 |
Other (c) | 23 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 23 |
|  | $218 |  |  |  | $116 |  |  |  | $83 |  |  |  | $61 |  |  |  | $41 |  |  |  | $113 |  |  |  | $632 |
(a) | Includes payments required by PPAs for capacity rights and minimum quantities of MWhs required to be purchased. In July 2018, IPL entered into an amendment to shorten the term of the DAEC PPA by five years in exchange for a $110 million buyout payment by IPL in September 2020, subject to IUB approval. In December 2018, IPL received an order from the IUB, which was effective in January 2019, approving recovery of the buyout payment. As a result, Alliant Energy’s and IPL’s amounts in the above table do not include the September 2020 buyout payment, and the minimum future commitments reflect IPL’s purchase of capacity and the resulting energy from DAEC through December 2025, the original term of the PPA prior to the amendment. Amounts in the above table for 2021 and beyond relate to the DAEC PPA.
(b) | Corporate Services entered into system-wide coal contracts on behalf of IPL and WPL that include minimum future commitments. These commitments were assigned to IPL and WPL based on information available as of December 31, 2018 regarding expected future usage, which is subject to change.
(c) | Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2018.
(c) Legal Proceedings - Alliant Energy, IPL and WPL are involved in legal and administrative proceedings before various courts and agencies with respect to matters arising in the ordinary course of business. Although unable to predict the outcome of these matters, Alliant Energy, IPL and WPL believe that appropriate reserves have been established and final disposition of these actions will not have a material effect on their financial condition or results of operations. (e) Environmental Matters - Alliant Energy, IPL and WPL are subject to environmental regulations as a result of their current and past operations. These regulations are designed to protect public health and the environment and have resulted in compliance, remediation, containment and monitoring obligations, which are recorded as current and non-current environmental liabilities. Substantially all of the environmental liabilities recorded on the balance sheets relate to MGP sites. MGP Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. At December 31, 2018, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions). At December 31, 2018, such amounts for WPL were not material.
| Alliant Energy |  | IPL
Range of estimated future costs |  | $11 |  | - | $29 |  |  | $8 |  | - | $24
Current and non-current environmental liabilities | 15 |  | 12
IPL Consent Decree - In 2015, the U.S. District Court for the Northern District of Iowa approved a Consent Decree that IPL entered into with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa, thereby resolving potential CAA issues associated with emissions from IPL’s coal-fired generating facilities in Iowa. IPL has completed various requirements under the Consent Decree. IPL’s remaining requirements include installing an SCR system or equivalent NOx reduction system at Ottumwa by December 31, 2019, and fuel switching or retiring Burlington by December 31, 2021 and Prairie Creek Units 1 and 3 by December 31, 2025. Alliant Energy and IPL currently expect to recover material costs incurred by IPL related to compliance with the terms of the Consent Decree from IPL’s electric customers. Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however future capital investments and/or modifications to EGUs to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters include, among others: Effluent Limitation Guidelines, CCR Rule, and various legislation and EPA regulations to monitor and regulate the emission of GHG, including the CAA. (f) Credit Risk - IPL provides retail electric and gas services in Iowa and wholesale electric service in Minnesota, Illinois and Iowa. WPL provides retail electric and gas services and wholesale electric service in Wisconsin. The geographic concentration of IPL’s and WPL’s customers did not contribute significantly to overall credit risk exposure. In addition, as a result of a diverse customer base, IPL and WPL did not have any significant credit risk concentration for receivables arising from the sale of electricity or gas services. Alliant Energy, IPL and WPL are subject to credit risk related to the ability of counterparties to meet their contractual payment obligations or the potential non-performance of counterparties to deliver contracted commodities and other goods or services at the contracted price. Credit policies are maintained to mitigate credit risk. These credit policies include evaluation of the financial condition of certain counterparties, use of credit risk-related contingent provisions in certain agreements that require credit support from counterparties not meeting specific criteria, diversification of counterparties to reduce concentrations of credit risk and the use of standardized agreements that facilitate the netting of cash flows associated with certain counterparties. Based on these credit policies and counterparty diversification, as well as utility cost recovery mechanisms, it is unlikely that counterparty non-performance would have a material effect on financial condition or results of operations. However, there is no assurance that these items will protect against all losses from counterparty non-performance. Refer to Notes 5(a) and 15 for details of allowances for doubtful accounts and credit risk-related contingent features, respectively. (g) Collective Bargaining Agreements - At December 31, 2018, employees covered by collective bargaining agreements represented 55%, 63% and 82% of total employees of Alliant Energy, IPL and WPL, respectively. In May 2019, WPL’s collective bargaining agreement with International Brotherhood of Electrical Workers Local 965 expires, representing 26% and 82% of total employees of Alliant Energy and WPL, respectively.

X
- Definition The entire disclosure for commitments and contingencies. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -URI http://asc.fasb.org/topic&trid=2127136 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -URI http://asc.fasb.org/topic&trid=2144648 + Details
Name: | us-gaap_CommitmentsAndContingenciesDisclosureTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=lnt_IplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=lnt_WplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |