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Income Taxes (Details) (USD $)
In Millions, unless otherwise specified |
9 Months Ended | |||
|---|---|---|---|---|
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Sep. 30, 2012
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Dec. 31, 2011
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Sep. 30, 2012
State Jurisdiction [Member]
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Sep. 30, 2012
Xcel Energy Inc. [Member]
Internal Revenue Service (IRS) [Member]
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| Income Tax Examination [Line Items] | ||||
| Year(s) no longer subject to audit as statute of limitations has expired | 2008 | |||
| Earliest year subject to examination | 2007 | 2009 | ||
| Year(s) under examination | None | 2010 and 2011 | ||
| Unrecognized Tax Benefits [Abstract] | ||||
| Unrecognized tax benefit - Permanent tax positions | $ 0.2 | $ 0.2 | ||
| Unrecognized tax benefit - Temporary tax positions | 4.8 | 4.6 | ||
| Total unrecognized tax benefit | 5.0 | 4.8 | ||
| NOL and tax credit carryforwards | (2.1) | (2.0) | ||
| Amounts accrued for penalties related to unrecognized tax benefits | $ 0 | $ 0 | ||