MEMBERS' EQUITY Table 2 (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
AccumulatedOtherComprehensiveIncomeLoss [Roll Forward]
Balance as of January 1, 2014	$ 8,941
Other comprehensive income (loss)	(948)
Balance as of March 31, 2014	7,993
Share of NS Energy's OCI [Member]
AccumulatedOtherComprehensiveIncomeLoss [Roll Forward]
Balance as of January 1, 2014	(9,417)
Other comprehensive loss before reclassification adjustments	(219)
Amounts reclassified from accumulated other comprehensive income (loss) (a)	0
Other comprehensive income (loss)	(219)
Balance as of March 31, 2014	(9,636)
Pension and Other Postretirement Benefit Plan Adjustment [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)	(729)
Other comprehensive income (loss)	(729)
Balance as of March 31, 2014	17,629
Accumulated Other Comprehensive Income (Loss) [Member]
AccumulatedOtherComprehensiveIncomeLoss [Roll Forward]
Balance as of January 1, 2014	8,941
Other comprehensive loss before reclassification adjustments	(219)
Amounts reclassified from accumulated other comprehensive income (loss) (a)	(729)
Other comprehensive income (loss)	(948)
Balance as of March 31, 2014	$ 7,993