Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 14

-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e681-108580

Reference 2: 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 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 14A

-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669686-108580

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 31

-Article 5

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15D

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 130

-Paragraph 14, 17, 26

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

+ Details

MEMBERS' EQUITY Table 3 (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (31,736)	$ (31,736)	$ (31,825)	$ (32,022)
Net current-period OCI	89	286
NS Energy OCI adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net current-period OCI	(421)	(734)
Amortization of prior service credit [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net current-period OCI	(60)	(120)
Amortization of net loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net current-period OCI	570	1,140
Share of NS Energy's OCI [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(9,477)	(9,477)	(9,056)	(8,743)
Net current-period OCI	(421)	(734)
Share of NS Energy's OCI [Member] \| NS Energy OCI adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net current-period OCI	(421)	(734)
Share of NS Energy's OCI [Member] \| Amortization of prior service credit [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net current-period OCI	0	0
Share of NS Energy's OCI [Member] \| Amortization of net loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net current-period OCI	0	0
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(22,259)	(22,259)	(22,769)	(23,279)
Net current-period OCI	510	1,020
Accumulated Defined Benefit Plans Adjustment [Member] \| NS Energy OCI adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net current-period OCI	0	0
Accumulated Defined Benefit Plans Adjustment [Member] \| Amortization of prior service credit [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net current-period OCI	(60)	(120)
Accumulated Defined Benefit Plans Adjustment [Member] \| Amortization of net loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net current-period OCI	$ 570	$ 1,140