v3.20.1

REVENUE FROM CONTRACTS WITH CUSTOMERS Narrative 1 (Details) - USD ($) $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2020 | Mar. 31, 2019
Revenue recognized | $ 10,765 | $ 34,714
Petroleos de Venezuela, S.A. (PDVSA) [Member] |  |
Revenue recognized |  | $ 16,300

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- Definition Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045 + Details
Name: | us-gaap_ContractWithCustomerLiabilityRevenueRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Details
Name: | srt_MajorCustomersAxis=ns_PetroleosdeVenezuelaS.A.PDVSAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |