v3.19.3.a.u2

INCOME TAXES Narrative 3 (Details) $ in Millions | Dec. 31, 2019 USD ($)
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U.S. [Member] |
Capital Loss Carryforwards [Line Items] |
Capital loss carryforward | $ 18.4

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- Definition Amount of capital loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References No definition available. + Details
Name: | ns_CapitalLossCarryforwards
Namespace Prefix: | ns_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition [Line Items] for Capital Loss Carryforwards [Table] + References No definition available. + Details
Name: | ns_CapitalLossCarryforwardsLineItems
Namespace Prefix: | ns_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=us-gaap_DomesticCountryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |