SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Jun. 30, 2015
Accounting Policies [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION - These notes are an integral part of the accompanying unaudited financial statements of The Laclede Group, Inc. (Laclede Group or the Company), as well as Laclede Gas Company (Laclede Gas or the Missouri Utilities) and Alabama Gas Corporation (Alagasco or the Alabama Utility). Laclede Gas, which includes the operations of Missouri Gas Energy (MGE), and Alagasco are wholly owned subsidiaries of the Company. Collectively, Laclede Gas and Alagasco are referred to as the Utilities. The accompanying unaudited financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) for interim financial information with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the disclosures required for complete financial statements. In the opinion of management, the accompanying unaudited financial statements include all adjustments (consisting of only normal recurring accruals) necessary for the fair presentation of the results of operations for the periods presented. This Form 10-Q should be read in conjunction with the Notes to the Financial Statements contained in Laclede Group's, Laclede Gas' and Alagasco's Annual Reports on Form 10-K or 10-KT for the fiscal year or transition period, as applicable, ended September 30, 2014. The consolidated financial position, results of operations, and cash flows of Laclede Group are primarily derived from the financial position, results of operations, and cash flows of the Utilities. In compliance with GAAP, transactions between the Utilities and their affiliates, as well as intercompany balances on the Utilities' Balance Sheets, have not been eliminated from the Utilities' financial statements. As a result of the Company's August 31, 2014 acquisition of Alagasco, the Company's results of operations for the three and nine months ended June 30, 2015 include Alagasco, which impacts the comparability of the current year financial statements to prior years for Laclede Group. Nonetheless, the separate financial statements for Alabama Gas Corporation are comparable as presented. For a further discussion of the acquisition, see Note 2, Alagasco Acquisition. The Utilities are regulated natural gas distribution utilities. Due to the seasonal nature of the Utilities, Laclede Group’s earnings are typically concentrated during the heating season of November through April each fiscal year. As a result, the interim statements of income for Laclede Group are not necessarily indicative of annual results or representative of succeeding quarters of the fiscal year.
REVENUE RECOGNITION	REVENUE RECOGNITION - The Utilities read meters and bill customers on monthly cycles. The Missouri Utilities record their gas utility revenues from gas sales and transportation services on an accrual basis that includes estimated amounts for gas delivered but not yet billed. The accruals for unbilled revenues are reversed in the subsequent accounting period when meters are actually read and customers are billed. The amounts of accrued unbilled revenues for Laclede Gas at June 30, 2015 and September 30, 2014 were $26.4 and $29.4, respectively. Alagasco records natural gas distribution revenues in accordance with the tariff established by the Alabama Public Service Commission (APSC). The amount of accrued unbilled revenues, which is not recorded as revenue until billed, for Alagasco at June 30, 2015 and September 30, 2014 were $5.4 and $5.2, respectively. Laclede Group's other subsidiaries, including LER, record revenues when earned, either when the product is delivered or when services are performed. In the course of its business, LER enters into commitments associated with the purchase or sale of natural gas. Certain of LER’s derivative natural gas contracts are designated as normal purchases or normal sales and, as such, are excluded from the scope of Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 815, “Derivatives and Hedging.” Those contracts are accounted for as executory contracts and recorded on an accrual basis. Revenues and expenses from such contracts are recorded using a gross presentation. Contracts not designated as normal purchases or normal sales are recorded as derivatives with changes in fair value recognized in earnings in the periods prior to physical delivery. Certain of LER’s wholesale purchase and sale transactions are classified as trading activities for financial reporting purposes. Under GAAP, revenues and expenses associated with trading activities are presented on a net basis in Gas Marketing Operating Revenues in the Condensed Consolidated Statements of Income. This net presentation has no effect on operating income or net income.
GROSS RECEIPTS TAXES	GROSS RECEIPTS TAXES - Gross receipts taxes associated with the Utilities' services are imposed on the Utilities and billed to customers. The revenue and expense amounts are recorded gross in the "Operating Revenues" and "Taxes, other than income taxes" lines, respectively, in the Company's Condensed Consolidated Statements of Income and the Utilities' Condensed Statements of Income.
REGULATED OPERATIONS	REGULATED OPERATIONS - The Utilities account for their regulated operations in accordance with FASB ASC Topic 980, “Regulated Operations.” This Topic sets forth the application of GAAP for those companies whose rates are established by or are subject to approval by an independent third-party regulator. The provisions of this accounting guidance require, among other things, that financial statements of a regulated enterprise reflect the actions of regulators, where appropriate. These actions may result in the recognition of revenues and expenses in time periods that are different than non-regulated enterprises. When this occurs, costs are deferred as assets in the balance sheet (regulatory assets) and recorded as expenses when those amounts are reflected in rates. In addition, regulators can impose liabilities upon a regulated company for amounts previously collected from customers and for recovery of costs that are expected to be incurred in the future (regulatory liabilities). Management believes that the current regulatory environment supports the continued use of these regulatory accounting principles and that all regulatory assets and regulatory liabilities are recoverable or refundable through the regulatory process.
GOODWILL	GOODWILL - Goodwill is measured as the excess of the acquisition-date fair value of the consideration transferred over the amount of acquisition-date identifiable assets acquired net of assumed liabilities.
NEW ACCOUNTING PRONOUNCEMENTS	NEW ACCOUNTING PRONOUNCEMENTS - In May 2014, the FASB issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers. This standard is intended to improve the financial reporting requirements for revenue from contracts with customers by providing a principles-based approach to the recognition of revenue. The core principle of the standard is when an entity transfers goods or services to customers it will recognize revenue in an amount that reflects the consideration the entity expects to be entitled to for those goods or services. The standard outlines a five-step model and related application guidance, which replaces most existing revenue recognition guidance. ASU 2014-09 also requires disclosures that will enable users of financial statements to understand the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. The guidance was originally to be effective for fiscal years, and interim periods within those years, beginning after December 15, 2016, with early adoption not permitted. In July 2015, the FASB approved a one-year deferral of the effective date, but companies may choose to adopt it as of the original effective date. The Company, Laclede Gas and Alagasco are currently assessing the available transition methods and the potential impacts of the standard, which must be adopted by the first quarter of fiscal 2019. In April 2015, the FASB issued ASU No. 2015-03, Interest – Imputation of Interest: Simplifying the Presentation of Debt Issuance Costs. Currently different balance sheet presentation requirements exist for debt issuance costs and debt discount and premium. Debt issuance costs are recorded as a deferred charge (asset), while debt discount and debt premium costs are recorded as a liability adjustment. This standard will require debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by this standard. The guidance is effective for fiscal years beginning after December 15, 2015 and interim periods within those years, with early adoption permitted. The application of this standard will be retrospective, wherein the balance sheet of each individual period presented will be adjusted to reflect the period-specific impacts of applying the new guidance. The Company, Laclede Gas and Alagasco are currently assessing the timing and impacts of adopting this standard, which must be adopted by the first quarter of fiscal year 2017.

Disclosure of accounting policy for revenue recognition. If the entity has different policies for different types of revenue transactions, the policy for each material type of transaction is generally disclosed. If a sales transaction has multiple element arrangements (for example, delivery of multiple products, services or the rights to use assets) the disclosure may indicate the accounting policy for each unit of accounting as well as how units of accounting are determined and valued. The disclosure may encompass important judgment as to appropriateness of principles related to recognition of revenue. The disclosure also may indicate the entity's treatment of any unearned or deferred revenue that arises from the transaction.