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Rate Matters (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
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Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2013 PSCW [Member] | Dec. 31, 2011 PSCW [Member] | Dec. 31, 2014 PSCW [Member] Approved Future Rate Matters [Member] | Dec. 31, 2013 PSCW [Member] Columbia Environmental Project [Member] | Dec. 31, 2012 PSCW [Member] Columbia Environmental Project [Member] | Dec. 31, 2011 PSCW [Member] Columbia Environmental Project [Member] | Dec. 31, 2014 PSCW [Member] Columbia Environmental Project [Member] Approved Future Rate Matters [Member] | Dec. 31, 2013 Electric Rate Proceeding [Member] PSCW [Member] | Dec. 31, 2012 Electric Rate Proceeding [Member] PSCW [Member] | Dec. 31, 2011 Electric Rate Proceeding [Member] PSCW [Member] | Dec. 31, 2014 Electric Rate Proceeding [Member] PSCW [Member] Approved Future Rate Matters [Member] | Dec. 31, 2013 Gas Rate Proceeding [Member] PSCW [Member] | Dec. 31, 2012 Gas Rate Proceeding [Member] PSCW [Member] | Dec. 31, 2011 Gas Rate Proceeding [Member] PSCW [Member] | Dec. 31, 2014 Gas Rate Proceeding [Member] PSCW [Member] Approved Future Rate Matters [Member]
Public Utilities, Rate Matters [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Authorized rate increase (decrease), percentage |  |  |  |  |  |  |  |  |  |  | 3.80% | 4.30% | 2.30% | 0.00% | 1.00% | 0.30% | 1.00% | 0.00%
Authorized rate increase (decrease), amount |  |  |  |  |  |  |  |  |  |  | $ 14.9 | $ 15.7 | $ 8.0 | $ 0 | $ 1.6 | $ 0.6 | $ 1.9 | $ 0
Authorized AFUDC rate | 50.00% | 50.00% | 50.00% |  |  |  | 50.00% | 100.00% | 100.00% | 100.00% |  |  |  |  |  |  |  |
Return of fuel rule surplus credit, to be amortized |  |  |  |  |  | 6.2 |  |  |  |  |  |  |  |  |  |  |  |
Authorized return on common stock |  |  |  | 10.30% | 10.30% | 10.30% |  |  |  |  |  |  |  |  |  |  |  |
Approved equity capital structure, percentage |  |  |  |  | 58.10% |  |  |  |  |  |  |  |  |  |  |  |  |
Fuel Rules [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fuel rules, bandwidth |  |  |  | 2.00% | 2.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Fuel rules, electric fuel costs, deferral, upper threshold | 102.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fuel rules, electric fuel costs, deferral, lower threshold | 98.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fuel rules, deferred electric cost | $ (6.7) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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- Definition Pursuant to the provisions of the rate order, the fuel rules bandwidth will be plus or minus this percentage. + References No definition available. + Details
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- Definition The amount of electric fuel-related costs in which an entity has deferred outside the symmetrical cost tolerance band authorized by a regulatory agency in the most recent rate order. + References No definition available. + Details
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- Definition Under fuel rules, the amount in which an entity is required to defer the benefit of lower costs if actual electric fuel costs were less than the allowed electric fuel costs in latest rate order. + References No definition available. + Details
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- Definition Under fuel rules, the amount in which an entity would defer if actual electric fuel costs exceeded allowed electric fuel costs in latest rate order. + References No definition available. + Details
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- Definition Percentage of approved equity capital structure + References No definition available. + Details
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- Definition Amount of public utility's approved rate increase (decrease) by regulatory agency + References No definition available. + Details
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- Definition Percentage of public utility's approved rate increase (decrease) by regulatory agency. + References No definition available. + Details
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- Definition Percentage of public utility's approved return on equity. + References No definition available. + Details
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- Definition The fuel rules surplus credit that is not required to be refunded to customers and will be amortized. The fuel credit will accrue interest at weighted cost of capital. + References No definition available. + Details
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- Definition Disclosure of the effective rate for the period representing (a) total additions to qualifying regulated assets for allowance for funds used during construction, (b) divided by the sum of debt and equity funds used for construction. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 835 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6501569&loc=d3e55921-110430 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 835 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6501662&loc=d3e56162-110433 + Details
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