STATEMENTS OF CASH FLOWS Table 1 (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Decrease (increase) in current assets:
Receivable from related parties	$ (4,497)	$ (6,298)
Income tax receivable	0	(23)
Other receivables	(429)	(158)
Other current assets	(23)	15
Increase (decrease) in current liabilities:
Accounts payable	73	(601)
Accrued compensation expense	3,642	4,315
Accrued liabilities	0	(41)
Taxes other than income tax	(1,101)	(992)
Changes in current assets and liabilities	$ (2,335)	$ (3,783)

Name:	nsh_SupplementalCashFlowInformationDecreaseIncreaseInCurrentAssetsAbstract
Namespace Prefix:	nsh_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	nsh_SupplementalCashFlowInformationDecreaseIncreaseInCurrentLiabilitiesAbstract
Namespace Prefix:	nsh_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The increase (decrease) during the reporting period in the aggregate amount of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

+ Details

Name:	us-gaap_IncreaseDecreaseInAccountsPayable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The increase (decrease) during the reporting period in the aggregate amount of expenses incurred but not yet paid.

+ References

+ Details

Name:	us-gaap_IncreaseDecreaseInAccruedLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate increase (decrease) during the reporting period in the amount due from the following types of related parties: a parent company and its subsidiaries; subsidiaries of a common parent; an entity and trust for the benefit of employees, such as pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; an entity and its principal owners, management, or member of their immediate families, affiliates, or other parties with the ability to exert significant influence.

+ References

+ Details

Name:	us-gaap_IncreaseDecreaseInDueFromRelatedPartiesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The increase (decrease) during the reporting period in the aggregate amount of obligations related to services received from employees, such as accrued salaries and bonuses, payroll taxes and fringe benefits.

+ References

+ Details

Name:	us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The increase (decrease) during the reporting period in income taxes receivable, which represents the amount due from tax authorities for refunds of overpayments or recoveries of income taxes paid.

+ References

+ Details

Name:	us-gaap_IncreaseDecreaseInIncomeTaxesReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The increase (decrease) during the reporting period of all assets and liabilities used in operating activities.

+ References

+ Details

Name:	us-gaap_IncreaseDecreaseInOperatingCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The increase (decrease) during the reporting period in other amounts due to the reporting entity, which are not otherwise defined in the taxonomy.

+ References

+ Details

Name:	us-gaap_IncreaseDecreaseInOtherReceivables
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The increase (decrease) during the reporting period in the amount of outstanding money paid in advance for goods or services that bring economic benefits for future periods.

+ References

+ Details

Name:	us-gaap_IncreaseDecreaseInPrepaidExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The increase (decrease) during the period in the amount of cash payments due to taxing authorities for non-income-related taxes.

+ References

+ Details

Name:	us-gaap_IncreaseDecreaseInPropertyAndOtherTaxesPayable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration