v3.20.2

PARTNERS' EQUITY (Tables) | 6 Months Ended
--- | ---
Jun. 30, 2020
Distribution Made to Preferred Limited Partner [Line Items] |
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] | The balance of and changes in the components included in AOCI were as follows:
| 2020 |  |  |  |  |  |  |  | 2019 |  |  |  |  |  |
| Foreign Currency Translation |  | Cash Flow Hedges |  | Pension and Other Postretirement Benefits |  | Total |  | Foreign Currency Translation |  | Cash Flow Hedges |  | Pension and Other Postretirement Benefits |  | Total
| (Thousands of Dollars) |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance as of March 31 | $ | (50,600) |  |  | $ | (45,307) |  |  | $ | (8,302) |  |  | $ | (104,209) |  |  | $ | (45,823) |  |  | $ | (6,623) |  |  | $ | (7,258) |  |  | $ | (59,704) |
Other comprehensive income (loss): |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other comprehensive income (loss) before reclassification adjustments | 2,638 |  |  | (461) |  |  | — |  |  | 2,177 |  |  | 1,392 |  |  | (9,784) |  |  | — |  |  | (8,392) |
Net gain on pension costs reclassified into other income, net | — |  |  | — |  |  | (305) |  |  | (305) |  |  | — |  |  | — |  |  | (578) |  |  | (578) |
Net loss on cash flow hedges reclassified into interest expense, net | — |  |  | 878 |  |  | — |  |  | 878 |  |  | — |  |  | 1,005 |  |  | — |  |  | 1,005 |
Other | — |  |  | — |  |  | 4 |  |  | 4 |  |  | — |  |  | — |  |  | 6 |  |  | 6 |
Other comprehensive income (loss) | 2,638 |  |  | 417 |  |  | (301) |  |  | 2,754 |  |  | 1,392 |  |  | (8,779) |  |  | (572) |  |  | (7,959) |
Balance as of June 30 | $ | (47,962) |  |  | $ | (44,890) |  |  | $ | (8,603) |  |  | $ | (101,455) |  |  | $ | (44,431) |  |  | $ | (15,402) |  |  | $ | (7,830) |  |  | $ | (67,663) |
| 2020 |  |  |  |  |  |  |  | 2019 |  |  |  |  |  |
| Foreign Currency Translation |  | Cash Flow Hedges |  | Pension and Other Postretirement Benefits |  | Total |  | Foreign Currency Translation |  | Cash Flow Hedges |  | Pension and Other Postretirement Benefits |  | Total
| (Thousands of Dollars) |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance as of January 1 | $ | (43,772) |  |  | $ | (16,124) |  |  | $ | (8,000) |  |  | $ | (67,896) |  |  | $ | (47,299) |  |  | $ | (893) |  |  | $ | (6,686) |  |  | $ | (54,878) |
Other comprehensive (loss) income: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other comprehensive (loss) income before reclassification adjustments | (4,190) |  |  | (30,291) |  |  | — |  |  | (34,481) |  |  | 2,868 |  |  | (16,592) |  |  | — |  |  | (13,724) |
Net gain on pension costs reclassified into other income, net | — |  |  | — |  |  | (610) |  |  | (610) |  |  | — |  |  | — |  |  | (1,157) |  |  | (1,157) |
Net loss on cash flow hedges reclassified into interest expense, net | — |  |  | 1,525 |  |  | — |  |  | 1,525 |  |  | — |  |  | 2,083 |  |  | — |  |  | 2,083 |
Other | — |  |  | — |  |  | 7 |  |  | 7 |  |  | — |  |  | — |  |  | 13 |  |  | 13 |
Other comprehensive (loss) income | (4,190) |  |  | (28,766) |  |  | (603) |  |  | (33,559) |  |  | 2,868 |  |  | (14,509) |  |  | (1,144) |  |  | (12,785) |
Balance as of June 30 | $ | (47,962) |  |  | $ | (44,890) |  |  | $ | (8,603) |  |  | $ | (101,455) |  |  | $ | (44,431) |  |  | $ | (15,402) |  |  | $ | (7,830) |  |  | $ | (67,663) |
Preferred Limited Partner [Member] |
Distribution Made to Preferred Limited Partner [Line Items] |
Distributions Made to Limited Partner, by Distribution [Table Text Block] | Distributions on our Series A, B and C Preferred Units are payable out of any legally available funds, accrue and are cumulative from the original issuance dates, and are payable on the 15th day (or next business day) of each of March, June, September and December of each year to holders of record on the first business day of each payment month as follows (until the distribution rate changes to a floating rate):
Units |  |  |  |  |  |  |  |  |  | Fixed Distribution Rate Per Unit Per Quarter |  | Fixed Distribution Per Quarter |  | Date at Which Distribution Rate Becomes Floating
|  |  |  |  |  |  |  |  |  |  |  | (Thousands of Dollars) |  |
Series A Preferred Units |  |  |  |  |  |  |  |  |  | $ | 0.53125 |  |  | $ | 4,813 |  |  | December 15, 2021
Series B Preferred Units |  |  |  |  |  |  |  |  |  | $ | 0.47657 |  |  | $ | 7,339 |  |  | June 15, 2022
Series C Preferred Units |  |  |  |  |  |  |  |  |  | $ | 0.56250 |  |  | $ | 3,881 |  |  | December 15, 2022
Common Limited Partner [Member] |
Distribution Made to Preferred Limited Partner [Line Items] |
Distributions Made to Limited Partner, by Distribution [Table Text Block] | The following table summarizes information about quarterly cash distributions declared for our common limited partners:
Quarter Ended |  | Cash Distributions Per Unit |  | Total Cash Distributions |  | Record Date |  | Payment Date
|  |  |  | (Thousands of Dollars) |  |  |  |
June 30, 2020 |  | $ | 0.40 |  |  | $ | 43,678 |  |  | August 7, 2020 |  | August 13, 2020
March 31, 2020 |  | $ | 0.40 |  |  | $ | 43,730 |  |  | May 11, 2020 |  | May 15, 2020
December 31, 2019 |  | $ | 0.60 |  |  | $ | 65,128 |  |  | February 10, 2020 |  | February 14, 2020

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DistributionMadeToLimitedPartnerLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of payment of cash or stock made to limited partner of limited partnership (LP). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 272 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 272 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055 + Details
Name: | us-gaap_DistributionsMadeToLimitedPartnerByDistributionTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the components of accumulated other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669686-108580 + Details
Name: | us-gaap_ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_PartnerTypeOfPartnersCapitalAccountAxis=ns_PreferredLimitedPartnerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PartnerTypeOfPartnersCapitalAccountAxis=ns_CommonLimitedPartnerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |