v3.19.3.a.u2

PARTNERS' EQUITY Narrative 1 (Details) | 6 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2018 | Dec. 31, 2017 Rate
Partners' Capital Notes [Abstract] |  |
General partner ownership interest | 2.00% | 2.00%

X
- Definition The general partner ownership interest (ownership percentage) in the limited partnership. Excludes other ownership interests held by the general partner in the limited partnership. + References No definition available. + Details
Name: | ns_GeneralPartnerOwnershipInterest
Namespace Prefix: | ns_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_PartnersCapitalNotesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration