Income Taxes (Details) (USD $) In Millions, unless otherwise specified			6 Months Ended
Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 State Jurisdiction [Member]	Jun. 30, 2012 Xcel Energy Inc. [Member] Internal Revenue Service (IRS) [Member]
Income Tax Examination [Line Items]
Year(s) no longer subject to audit as statute of limitations has expired				2007
Earliest year subject to examination			2007	2008
Year(s) under examination			None	None
Unrecognized Tax Benefits [Abstract]
Unrecognized tax benefit - Temporary tax positions	$ 1.3	$ 1.5
NOL carryforwards	(1.0)	(1.1)
Amounts accrued for penalties related to unrecognized tax benefits	$ 0	$ 0

The earliest open tax year(s) subject to income tax examination by a taxing authority.

No definition available.

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- Definition

The tax year(s) no longer subject to audit as the statute of limitations has expired in connection with the income tax examination by a taxing authority.

+ References

No definition available.

+ Details

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- Definition

Tax benefits associated with NOL carryforwards that reduce unrecognized tax benefits.

+ References

No definition available.

+ Details

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- Definition

The total amount of unrecognized tax benefits for which the ultimate deductibility is highly certain but for which there is uncertainty about the timing of such deductibility and, if recognized, would not affect the effective tax rate but would accelerate the payment of cash to the taxing authority to an earlier period.

+ References

No definition available.

+ Details

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- Details

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- Definition

The tax year(s) being audited in connection with the income tax examination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (d)(2)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319

+ Details

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- Details

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- Definition

This element represents the amount of statutory penalties accrued as of the date of the statement of financial position for a tax position claimed or expected to be claimed by the entity, in its tax return, that does not meet the minimum statutory threshold to avoid payment of penalties.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 48

-Paragraph 16

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 48

-Paragraph 21

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319

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