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Operations and Significant Accounting Policies (Tables) | 6 Months Ended
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Jun. 30, 2013
Operations and Significant Accounting Policies [Abstract] |
Inventories [Table Text Block] |
Inventories | June 30, 2013 |  |  | December 31, 2012 |
Millions |  |  |
Fuel |  | $25.3 |  |  |  | $28.0 |
Materials and Supplies | 45.7 |  |  | 41.8 |
Total Inventories |  | $71.0 |  |  |  | $69.8 |
Prepayments and Other Current Assets [Table Text Block] |
Prepayments and Other Current Assets | June 30, 2013 |  |  | December 31, 2012 |
Millions |  |  |
Deferred Fuel Adjustment Clause |  | $18.3 |  |  |  | $22.5 |
Other | 7.9 |  |  | 11.1 |
Total Prepayments and Other Current Assets |  | $26.2 |  |  |  | $33.6 |
Other Current and Non-Current Liabilities [Table Text Block] |
Other Current Liabilities | June 30, 2013 |  |  | December 31, 2012 |
Millions |  |  |
Customer Deposits |  | $29.1 |  |  |  | $28.8 |
Other | 31.7 |  |  | 33.8 |
Total Other Current Liabilities |  | $60.8 |  |  |  | $62.6 |
Other Non-Current Liabilities | June 30, 2013 |  |  | December 31, 2012 |
Millions |  |  |
Asset Retirement Obligation |  | $81.6 |  |  |  | $77.9 |
Other | 47.7 |  |  | 45.4 |
Total Other Non-Current Liabilities |  | $129.3 |  |  |  | $123.3 |
Supplemental Statement of Cash Flows Information [Table Text Block] | Supplemental Statement of Cash Flows Information.
For the Six Months Ended June 30, | 2013 |  |  | 2012 |
Millions |  |  |
Cash Paid During the Period for Interest – Net of Amounts Capitalized |  | $22.8 |  |  |  | $21.7 |
Cash Paid During the Period for Income Taxes |  | $0.6 |  |  |  | $0.2 |
Noncash Investing and Financing Activities |  |  |  |  |
Decrease in Accounts Payable for Capital Additions to Property, Plant and Equipment |  | $28.2 |  |  |  | $14.8 |
Capitalized Asset Retirement Costs |  | $1.9 |  |  |  | $2.4 |
AFUDC – Equity |  | $2.1 |  |  |  | $1.9 |

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- Definition Tabular disclosure of the carrying amount as of the balance sheet date of merchandise, goods, commodities, or supplies held for future sale or to be used in manufacturing, servicing or production process. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 2 -Paragraph 6 -Subparagraph a,b,c -Article 5 + Details
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