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