EMPLOYEE BENEFIT PLANS AND UNIT-BASED COMPENSATION Narrative (Details) - USD ($)	Mar. 01, 2016	Jun. 30, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Employee benefit plans, obligations transferred	$ 32,700,000
Employee benefit plans, amounts recognized in balance sheet		$ 0
Accumulated other comprehensive loss impact of Employee Transfer	$ 4,201,000
Unit-based awards transferred	688,647

The aggregate net obligation recognized in the balance sheet associated with the defined benefit plan(s) that was transferred out in connection with the Employee Transfer.

No definition available.

+ Details

Name:	nsh_DefinedBenefitPlanAmountsRecognizedInBalanceSheetTransferred
Namespace Prefix:	nsh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount after tax of the reclassification adjustment out of accumulated other comprehensive loss attributable to the Employee Transfer.

+ References

No definition available.

+ Details

Name:	nsh_ReclassificationOutOfAccumulatedOtherComprehensiveLossEmployeeTransfer
Namespace Prefix:	nsh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of unit-based payment awards transferred in the Employee Transfer.

+ References

No definition available.

+ Details

Name:	nsh_UnitBasedAwardsTransferred
Namespace Prefix:	nsh_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate net amount recognized in the balance sheet associated with the defined benefit plan(s). Will normally be the same as the Defined Benefit Plan, Funded Status of Plan, Total.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=21915240&loc=d3e1703-114919

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration