MEMBERS' EQUITY Table 2 (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of January 1, 2014	$ 8,941
Other comprehensive income (loss)	(1,900)
Balance as of September 30, 2014	7,041
Share of NS Energy's OCI [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of January 1, 2014	(9,417)
Other comprehensive income (loss) before reclassification adjustments	478
Amounts reclassified from accumulated other comprehensive income (loss) (a)	0
Other comprehensive income (loss)	478
Balance as of September 30, 2014	(8,939)
Pension and Other Postretirement Benefit Plan Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of January 1, 2014	18,358
Other comprehensive income (loss) before reclassification adjustments	0
Amounts reclassified from accumulated other comprehensive income (loss) (a)	(2,378)
Other comprehensive income (loss)	(2,378)
Balance as of September 30, 2014	15,980
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of January 1, 2014	8,941
Other comprehensive income (loss) before reclassification adjustments	478
Amounts reclassified from accumulated other comprehensive income (loss) (a)	(2,378)
Other comprehensive income (loss)	(1,900)
Balance as of September 30, 2014	$ 7,041