v3.19.3.a.u2

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

X

- 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

X

- 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: