v3.19.3.a.u2

MERGER AND RELATED PARTY AGREEMENTS Table - Merger Calculation (Details) - USD ($) $ / shares in Units, $ in Thousands |  | 12 Months Ended
--- | --- | ---
Jul. 20, 2018 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Business Combinations [Abstract] |  |  |  |
Fair value of incremental NS common units issued | $ 335,106 |  |  |
Holdings debt and assumed net current liabilities | 52,075 |  |  |
Transaction costs | 15,897 |  |  |
Total consideration | 403,078 |  |  |
Carrying value of general partner interest | $ 25,999 |  |  |
Loss to common unitholders attributable to the Merger |  | $ 0 | $ (377,079) | $ 0
Basic weighted-average common units outstanding |  | 107,789,030 | 99,490,495 | 88,825,964
Loss per common unit attributable to the Merger |  |  | $ (3.79) |

X
- Definition Fair Value of Incremental Equity Interests Issued For Merger Transaction + References No definition available. + Details
Name: | ns_FairValueofIncrementalEquityInterestsIssuedForMergerTransaction
Namespace Prefix: | ns_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Gain (loss) attributable to common shareholders due to Merger + References No definition available. + Details
Name: | ns_GainLossAttributabletoCommonShareholdersDuetoMerger
Namespace Prefix: | ns_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Gain (Loss) Attributable to Common Shareholders Due to Merger, Per Share + References No definition available. + Details
Name: | ns_GainLossAttributabletoCommonShareholdersDuetoMergerPerShare
Namespace Prefix: | ns_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Liabilities Assumed From Merger Transaction + References No definition available. + Details
Name: | ns_LiabilitiesAssumedFromMergerTransaction
Namespace Prefix: | ns_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Total Consideration Transferred for Merger + References No definition available. + Details
Name: | ns_TotalConsiderationTransferredForMerger
Namespace Prefix: | ns_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of direct costs of the business combination including legal, accounting, and other costs incurred to consummate the business acquisition. + References No definition available. + Details
Name: | us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Definition The amount of the general partner's ownership interest. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 5 -Subparagraph (SAB Topic 4.F) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770 + Details
Name: | us-gaap_GeneralPartnersCapitalAccount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Weighted average number of limited partnership units outstanding determined by relating the portion of time within a reporting period that limited partnership units have been outstanding to the total time in that period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 5 -Subparagraph (SAB Topic 4.F) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770 + Details
Name: | us-gaap_WeightedAverageLimitedPartnershipUnitsOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration