Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Consolidated Statements of Comprehensive Income
Net income	$ 55,681	$ 54,971	$ 47,396
Reclassification adjustments for loss included in net income or reclassified to regulatory asset or liability			5,814
Net change in fair market value of open derivative contracts for period			(6,362)
Income taxes			209
Comprehensive income	$ 55,681	$ 54,971	$ 47,057

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the reporting entity. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, but excludes any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References+ Details

Before tax amount of the income statement impact of the reclassification adjustment of accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges realized in net income. Also includes reclassification adjustments of an entity's share of an equity investee's deferred hedging gain (loss) realized in net income.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 130

-Paragraph 18, 19

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 38

-Subparagraph c(3)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 220

-SubTopic 10

-Section 45

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e689-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 31, 46

-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 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e637-108580

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 130

-Paragraph 24

-Subparagraph b

-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 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 16

-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e709-108580

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e716-108580

Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Reclassification Adjustments

-URI http://asc.fasb.org/extlink&oid=6522872

+ Details

- Definition

Before tax amount of the change in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Also includes an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6441202&loc=d3e80720-113993

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 130

-Paragraph 24

-Subparagraph b

-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 220

-SubTopic 10

-Section 45

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e637-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 130

-Paragraph 17, 20

-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 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 10A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 38

-Subparagraph c(3)

-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 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 46

-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.

+ Details