Summary Of Significant Accounting Policies	3 Months Ended
Summary Of Significant Accounting Policies	Mar. 31, 2015
Summary Of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (a) General - The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the latest combined Annual Report on Form 10-K. In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the three months ended March 31, 2015 are not necessarily indicative of results that may be expected for the year ending December 31, 2015. A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred. Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes. Unless otherwise noted, the Notes herein exclude assets and liabilities held for sale for all periods presented. (b) New Accounting Pronouncements - Revenue Recognition - In May 2014, the Financial Accounting Standards Board issued an accounting standard providing principles for recognizing revenue for the transfer of promised goods or services to customers with the consideration to which the entity expects to be entitled in exchange for those goods or services. This standard also requires disclosures about the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. Alliant Energy, IPL and WPL are currently required to adopt this standard on January 1, 2017; however, in April 2015, the Financial Accounting Standards Board proposed to defer the effective date of this standard by one year. Alliant Energy, IPL and WPL are currently evaluating the impact of this standard on their financial condition and results of operations. Presentation of Debt Issuance Costs - In April 2015, the Financial Accounting Standards Board issued an accounting standard to simplify the presentation of debt issuance costs on the balance sheet. Under the new standard, debt issuance costs related to a recognized debt liability will be presented on the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. Alliant Energy, IPL and WPL are required to adopt this standard on January 1, 2016 and early adoption is permitted. Debt issuance costs represent less than 1% of total long-term debt.
IPL [Member]
Summary Of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (a) General - The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the latest combined Annual Report on Form 10-K. In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the three months ended March 31, 2015 are not necessarily indicative of results that may be expected for the year ending December 31, 2015. A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred. Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes. Unless otherwise noted, the Notes herein exclude assets and liabilities held for sale for all periods presented. (b) New Accounting Pronouncements - Revenue Recognition - In May 2014, the Financial Accounting Standards Board issued an accounting standard providing principles for recognizing revenue for the transfer of promised goods or services to customers with the consideration to which the entity expects to be entitled in exchange for those goods or services. This standard also requires disclosures about the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. Alliant Energy, IPL and WPL are currently required to adopt this standard on January 1, 2017; however, in April 2015, the Financial Accounting Standards Board proposed to defer the effective date of this standard by one year. Alliant Energy, IPL and WPL are currently evaluating the impact of this standard on their financial condition and results of operations. Presentation of Debt Issuance Costs - In April 2015, the Financial Accounting Standards Board issued an accounting standard to simplify the presentation of debt issuance costs on the balance sheet. Under the new standard, debt issuance costs related to a recognized debt liability will be presented on the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. Alliant Energy, IPL and WPL are required to adopt this standard on January 1, 2016 and early adoption is permitted. Debt issuance costs represent less than 1% of total long-term debt.
WPL [Member]
Summary Of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (a) General - The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the latest combined Annual Report on Form 10-K. In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the three months ended March 31, 2015 are not necessarily indicative of results that may be expected for the year ending December 31, 2015. A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred. Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes. Unless otherwise noted, the Notes herein exclude assets and liabilities held for sale for all periods presented. (b) New Accounting Pronouncements - Revenue Recognition - In May 2014, the Financial Accounting Standards Board issued an accounting standard providing principles for recognizing revenue for the transfer of promised goods or services to customers with the consideration to which the entity expects to be entitled in exchange for those goods or services. This standard also requires disclosures about the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. Alliant Energy, IPL and WPL are currently required to adopt this standard on January 1, 2017; however, in April 2015, the Financial Accounting Standards Board proposed to defer the effective date of this standard by one year. Alliant Energy, IPL and WPL are currently evaluating the impact of this standard on their financial condition and results of operations. Presentation of Debt Issuance Costs - In April 2015, the Financial Accounting Standards Board issued an accounting standard to simplify the presentation of debt issuance costs on the balance sheet. Under the new standard, debt issuance costs related to a recognized debt liability will be presented on the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. Alliant Energy, IPL and WPL are required to adopt this standard on January 1, 2016 and early adoption is permitted. Debt issuance costs represent less than 1% of total long-term debt.

- Definition

The entire disclosure for all significant accounting policies of the reporting entity.

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