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Segments Of Business (Schedule Of Operating Income Derived From Revenues And Expenses By Segment) (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Operating Revenues |  |  |  |  |  |  |  |  |  | $ 5,114.5 | $ 4,874.6 | $ 4,492.5
Operating Income (Loss) |  | $ (78.4) | $ (315.9) | $ 118.4 | $ 400.6 | $ 270.6 | $ 111.2 | $ 124.0 | $ 415.4 | 124.7 | 921.2 | 866.1
Consolidated Depreciation and Amortization |  |  |  |  |  |  |  |  |  | 599.6 | 570.3 | 547.1
Consolidated Assets |  | 21,804.0 |  |  |  | 19,961.7 |  |  |  | 21,804.0 | 19,961.7 | 18,691.9
Payments to Acquire Property Plant and Equipment Including Captial Expenditures From Current Liabilities And Equity Method Investments | [1] |  |  |  |  |  |  |  |  | 1,814.6 | 1,753.8 | 1,490.4
Gas Distribution Operations |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Operating Revenues |  |  |  |  |  |  |  |  |  | 3,406.4 |  |
Intersegment |  |  |  |  |  |  |  |  |  | 3,419.5 | 3,102.1 | 2,830.6
Operating Income (Loss) |  |  |  |  |  |  |  |  |  | (254.1) | 550.1 | 569.7
Consolidated Depreciation and Amortization |  |  |  |  |  |  |  |  |  | 301.0 | 269.3 | 252.9
Consolidated Assets |  | 13,527.0 |  |  |  | 12,048.8 |  |  |  | 13,527.0 | 12,048.8 | 11,096.4
Payments to Acquire Property Plant and Equipment Including Captial Expenditures From Current Liabilities And Equity Method Investments | [1] |  |  |  |  |  |  |  |  | 1,315.3 | 1,125.6 | 1,054.4
Electric Operations |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Operating Revenues |  |  |  |  |  |  |  |  |  | 1,707.4 |  |
Intersegment |  |  |  |  |  |  |  |  |  | 1,708.2 | 1,786.5 | 1,661.6
Operating Income (Loss) |  |  |  |  |  |  |  |  |  | 386.1 | 367.4 | 301.3
Consolidated Depreciation and Amortization |  |  |  |  |  |  |  |  |  | 262.9 | 277.8 | 274.5
Consolidated Assets |  | 5,735.2 |  |  |  | 5,478.6 |  |  |  | 5,735.2 | 5,478.6 | 5,233.3
Payments to Acquire Property Plant and Equipment Including Captial Expenditures From Current Liabilities And Equity Method Investments | [1] |  |  |  |  |  |  |  |  | 499.3 | 592.4 | 420.6
Corporate and Other |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Operating Revenues |  |  |  |  |  |  |  |  |  | 0.7 |  |
Intersegment |  |  |  |  |  |  |  |  |  | 518.3 | 511.8 | 426.8
Operating Income (Loss) |  |  |  |  |  |  |  |  |  | (7.3) | 3.7 | (4.9)
Consolidated Depreciation and Amortization |  |  |  |  |  |  |  |  |  | 35.7 | 23.2 | 19.7
Consolidated Assets |  | $ 2,541.8 |  |  |  | $ 2,434.3 |  |  |  | 2,541.8 | 2,434.3 | 2,362.2
Payments to Acquire Property Plant and Equipment Including Captial Expenditures From Current Liabilities And Equity Method Investments | [1] |  |  |  |  |  |  |  |  | 0.0 | 35.8 | 15.4
Eliminations |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Intersegment |  |  |  |  |  |  |  |  |  | (531.5) | (525.8) | (426.5)
Unaffiliated | Gas Distribution Operations |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Operating Revenues |  |  |  |  |  |  |  |  |  | 3,406.4 | 3,087.9 | 2,818.2
Unaffiliated | Electric Operations |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Operating Revenues |  |  |  |  |  |  |  |  |  | 1,707.4 | 1,785.7 | 1,660.8
Unaffiliated | Corporate and Other |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Operating Revenues |  |  |  |  |  |  |  |  |  | 0.7 | 1.0 | 13.5
Intersegment | Gas Distribution Operations |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Intersegment |  |  |  |  |  |  |  |  |  | 13.1 | 14.2 | 12.4
Intersegment | Electric Operations |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Intersegment |  |  |  |  |  |  |  |  |  | 0.8 | 0.8 | 0.8
Intersegment | Corporate and Other |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Intersegment |  |  |  |  |  |  |  |  |  | $ 517.6 | $ 510.8 | $ 413.3
[1] | Amounts differ from those presented on the Statements of Consolidated Cash Flows primarily due to the inclusion of capital expenditures included in current liabilities and AFUDC Equity.

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