SUBSEQUENT EVENT	12 Months Ended
Dec. 31, 2017
Subsequent Events [Abstract]
SUBSEQUENT EVENT	SUBSEQUENT EVENT On February 7, 2018, NuStar GP Holdings, NuStar Energy, Riverwalk Logistics, L.P., NuStar GP, LLC, Marshall Merger Sub LLC, a wholly owned subsidiary of NuStar Energy (Merger Sub), and Riverwalk Holdings, LLC entered into an Agreement and Plan of Merger (the Merger Agreement) pursuant to which Merger Sub will merge with and into NuStar GP Holdings with NuStar GP Holdings being the surviving entity (the Merger), such that NuStar Energy will be our sole member following the Merger. Pursuant to the Merger Agreement and at the effective time of the Merger, NuStar Energy’s partnership agreement will be amended and restated to, among other things, (i) cancel the incentive distribution rights, (ii) convert the 2% general partner interest in NuStar Energy into a non-economic management interest and (iii) provide the holders of NuStar Energy’s common units with voting rights in the election of the members of the board of directors of NuStar GP, LLC at an annual meeting, beginning in 2019. At the effective time of the Merger, each of our outstanding common units will be converted into the right to receive 0.55 of a NuStar Energy common unit. All of our common units, when converted, will cease to be outstanding and will automatically be cancelled and no longer exist. No fractional NuStar Energy common units will be issued in the Merger; instead, each holder of our common units otherwise entitled to receive a fractional NuStar Energy common unit will receive cash in lieu thereof. Furthermore, the 10,214,626 NuStar Energy common units currently owned by us will be cancelled and will cease to exist. At the effective time of the Merger, each outstanding award of NuStar GP Holdings restricted units will be converted, on the same terms and conditions as were applicable to the awards immediately prior to the Merger, into an award of NuStar Energy restricted units. The number of NuStar Energy restricted units subject to the converted awards will be determined as provided in the Merger Agreement. Each of our executive officers and directors has agreed and acknowledged that the Merger will not be deemed to trigger a “change of control” as defined under the NuStar GP Holdings plan or award, and has waived any rights to vesting, payment or other benefit thereunder that would arise upon a “change of control,” to which he or she might otherwise have been entitled. The Merger Agreement contains customary representations and warranties and covenants by each of the parties. Completion of the Merger is conditioned upon, among other things: (i) approval of the Merger Agreement by the affirmative vote of holders of a Unit Majority, as defined in the Second Amended and Restated Limited Liability Company Agreement of NuStar GP Holdings, as amended; (ii) the effectiveness of a registration statement on Form S-4 with respect to the issuance by NuStar Energy of its common units in connection with the Merger; (iii) the absence of certain legal injunctions or impediments prohibiting the transactions; (iv) the receipt of certain tax opinions from a nationally recognized tax counsel; and (v) the approval for the listing of NuStar Energy’s common units to be issued in the Merger on the New York Stock Exchange. NuStar Energy entered into a Support Agreement, dated as of February 7, 2018 (the Support Agreement), with Merger Sub, WLG Holdings, LLC, a Texas limited liability company (WLG Holdings), Mr. Greehey (together, WLG Holdings and Mr. Greehey are referred to as the Greehey Unitholders), and, for limited purposes, us, pursuant to which the Greehey Unitholders have agreed to vote in favor of the approval and adoption of the Merger Agreement, the approval of the Merger and any other action required in furtherance thereof submitted for the vote or written consent of our unitholders. The Greehey Unitholders collectively own approximately 21% of our outstanding units. The Support Agreement will terminate (i) at the effective time of the Merger, (ii) upon the termination of the Merger Agreement, or (iii) at such time as NuStar Energy and the Greehey Unitholders agree in writing to terminate the Support Agreement. After the Merger, the NuStar GP, LLC board of directors is expected to consist of nine members, initially composed of the six members of the NuStar GP, LLC board of directors and the three independent directors of the board of directors of NuStar GP Holdings. Additionally, on February 8, 2018, NuStar Energy announced that NuStar Energy’s management anticipates recommending to the board of directors of NuStar GP, LLC, and expects such board of directors to adopt, a reset of NuStar Energy’s quarterly distribution per common unit to $0.60 ($2.40 on an annualized basis), starting with the first-quarter distribution payable in May 2018. We expect to adjust the quarterly distribution to our members accordingly.

SUBSEQUENT EVENT

On February 7, 2018, NuStar GP Holdings, NuStar Energy, Riverwalk Logistics, L.P., NuStar GP, LLC, Marshall Merger Sub LLC, a wholly owned subsidiary of NuStar Energy (Merger Sub), and Riverwalk Holdings, LLC entered into an Agreement and Plan of Merger (the Merger Agreement) pursuant to which Merger Sub will merge with and into NuStar GP Holdings with NuStar GP Holdings being the surviving entity (the Merger), such that NuStar Energy will be our sole member following the Merger. Pursuant to the Merger Agreement and at the effective time of the Merger, NuStar Energy’s partnership agreement will be amended and restated to, among other things, (i) cancel the incentive distribution rights, (ii) convert the 2% general partner interest in NuStar Energy into a non-economic management interest and (iii) provide the holders of NuStar Energy’s common units with voting rights in the election of the members of the board of directors of NuStar GP, LLC at an annual meeting, beginning in 2019.

At the effective time of the Merger, each of our outstanding common units will be converted into the right to receive 0.55 of a NuStar Energy common unit. All of our common units, when converted, will cease to be outstanding and will automatically be cancelled and no longer exist. No fractional NuStar Energy common units will be issued in the Merger; instead, each holder of our common units otherwise entitled to receive a fractional NuStar Energy common unit will receive cash in lieu thereof. Furthermore, the 10,214,626 NuStar Energy common units currently owned by us will be cancelled and will cease to exist.

At the effective time of the Merger, each outstanding award of NuStar GP Holdings restricted units will be converted, on the same terms and conditions as were applicable to the awards immediately prior to the Merger, into an award of NuStar Energy restricted units. The number of NuStar Energy restricted units subject to the converted awards will be determined as provided in the Merger Agreement. Each of our executive officers and directors has agreed and acknowledged that the Merger will not be deemed to trigger a “change of control” as defined under the NuStar GP Holdings plan or award, and has waived any rights to vesting, payment or other benefit thereunder that would arise upon a “change of control,” to which he or she might otherwise have been entitled.

The Merger Agreement contains customary representations and warranties and covenants by each of the parties. Completion of the Merger is conditioned upon, among other things: (i) approval of the Merger Agreement by the affirmative vote of holders of a Unit Majority, as defined in the Second Amended and Restated Limited Liability Company Agreement of NuStar GP Holdings, as amended; (ii) the effectiveness of a registration statement on Form S-4 with respect to the issuance by NuStar Energy of its common units in connection with the Merger; (iii) the absence of certain legal injunctions or impediments prohibiting the transactions; (iv) the receipt of certain tax opinions from a nationally recognized tax counsel; and (v) the approval for the listing of NuStar Energy’s common units to be issued in the Merger on the New York Stock Exchange.

NuStar Energy entered into a Support Agreement, dated as of February 7, 2018 (the Support Agreement), with Merger Sub, WLG Holdings, LLC, a Texas limited liability company (WLG Holdings), Mr. Greehey (together, WLG Holdings and Mr. Greehey are referred to as the Greehey Unitholders), and, for limited purposes, us, pursuant to which the Greehey Unitholders have agreed to vote in favor of the approval and adoption of the Merger Agreement, the approval of the Merger and any other action required in furtherance thereof submitted for the vote or written consent of our unitholders. The Greehey Unitholders collectively own approximately 21% of our outstanding units. The Support Agreement will terminate (i) at the effective time of the Merger, (ii) upon the termination of the Merger Agreement, or (iii) at such time as NuStar Energy and the Greehey Unitholders agree in writing to terminate the Support Agreement.

After the Merger, the NuStar GP, LLC board of directors is expected to consist of nine members, initially composed of the six members of the NuStar GP, LLC board of directors and the three independent directors of the board of directors of NuStar GP Holdings.

Additionally, on February 8, 2018, NuStar Energy announced that NuStar Energy’s management anticipates recommending to the board of directors of NuStar GP, LLC, and expects such board of directors to adopt, a reset of NuStar Energy’s quarterly distribution per common unit to $0.60 ($2.40 on an annualized basis), starting with the first-quarter distribution payable in May 2018. We expect to adjust the quarterly distribution to our members accordingly.