FAIR VALUE MEASUREMENTS Table 2 (Details) (NS unit options [Member])	9 Months Ended	12 Months Ended
Sep. 30, 2013	Dec. 31, 2012
NS unit options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life in years	5.9	6.5
Expected volatility	24.10%	22.40%
Expected distribution yield	10.90%	10.30%
Risk-free interest rate	0.10%	0.20%

The weighted-average period of time share-based awards, for an entity accounted for under the equity method, are expected to be outstanding. A share-based award's expected term shall be determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior. An entity is required to aggregate individual awards into relatively homogeneous groups.

No definition available.

Name:	nsh_EquityMethodInvestmentShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageExpectedTerm
Namespace Prefix:	nsh_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration