MEMBERS' EQUITY Table 2 (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014
AccumulatedOtherComprehensiveIncomeLoss [Roll Forward]
Balance as of January 1, 2014	$ 8,941
Other comprehensive income (loss)	(930)
Balance as of June 30, 2014	8,011
Share of NS Energy's OCI [Member]
AccumulatedOtherComprehensiveIncomeLoss [Roll Forward]
Balance as of January 1, 2014	(9,417)
Other comprehensive loss before reclassification adjustments	1,047
Amounts reclassified from accumulated other comprehensive income (loss) (a)	0
Other comprehensive income (loss)	1,047
Balance as of June 30, 2014	(8,370)
Pension and Other Postretirement Benefit Plan Adjustments [Member]
AccumulatedOtherComprehensiveIncomeLoss [Roll Forward]
Balance as of January 1, 2014	18,358
Other comprehensive loss before reclassification adjustments	0
Amounts reclassified from accumulated other comprehensive income (loss) (a)	(1,977)
Other comprehensive income (loss)	(1,977)
Balance as of June 30, 2014	16,381
Accumulated Other Comprehensive Income (Loss) [Member]
AccumulatedOtherComprehensiveIncomeLoss [Roll Forward]
Balance as of January 1, 2014	8,941
Other comprehensive loss before reclassification adjustments	1,047
Amounts reclassified from accumulated other comprehensive income (loss) (a)	(1,977)
Other comprehensive income (loss)	(930)
Balance as of June 30, 2014	$ 8,011