v3.19.3.a.u2

LEASE ASSETS AND LIABILITIES Narrative 1 (Details) $ in Millions | Jan. 01, 2019 USD ($)
--- | ---
Leases [Abstract] |
Right-of-Use Assets Recognized at Transition | $ 207.0
Lease Liabilities Recognized at Transition | $ 192.0

X
- Definition Amount of lease liabilities recognized due to the adoption of ASC Topic 842. + References No definition available. + Details
Name: | ns_LeaseLiabilitiesRecognizedatTransition
Namespace Prefix: | ns_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of right-of-use assets recognized due to the adoption of ASC Topic 842. + References No definition available. + Details
Name: | ns_RightofUseAssetsRecognizedatTransition
Namespace Prefix: | ns_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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