UNIT-BASED COMPENSATION Table 4 (Details) (The 2006 LTIP [Member], USD $)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Restricted units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
NSH restricted units, beginning balance	83,638
NSH restricted units, granted	36,241
NSH restricted units, vested	(35,150)
NSH restricted units, ending balance	84,729	83,638
Weighted-average grant date fair value, period start	$ 29.77
Weighted-average grant date fair value, granted	$ 28.77	$ 30.53	$ 36.54
Weighted-average grant date fair value, vested	$ 28.82
Weighted-average grant date fair value, period end	$ 29.74	$ 29.77
Restricted units, employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
NSH restricted units, beginning balance	66,671
NSH restricted units, granted	25,640	24,970	21,935
NSH restricted units, vested	(26,893)
NSH restricted units, ending balance	65,418	66,671
Restricted units, non-employee directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
NSH restricted units, beginning balance	16,967
NSH restricted units, granted	10,601	9,987	6,156
NSH restricted units, vested	(8,257)
NSH restricted units, ending balance	19,311	16,967

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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- Definition

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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