EMPLOYEE BENEFIT PLANS Narrative (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | |
|---|---|---|---|
Mar. 01, 2016 |
Sep. 30, 2016 |
Sep. 30, 2016 |
|
| Compensation and Retirement Disclosure [Abstract] | |||
| Pension Plan, description | The NuStar Pension Plan (the Pension Plan) is a qualified non-contributory defined benefit pension plan that provides eligible U.S. employees with retirement income as calculated under a cash balance formula. Under the cash balance formula, benefits are based on age, service and interest credits, and employees become fully vested in their benefits upon attaining three years of vesting service. | ||
| Pension and OPEB assumptions | We estimate pension and other postretirement benefit obligations and costs from actuarial valuations. The actuarial valuations require the use of certain assumptions, including discount rates, expected long-term rates of return on plan assets and expected rates of compensation increase. The amortization of actuarial gains and losses reflects a corridor based on 10% of the greater of the projected benefit obligation or the market-related value of the pension plan assets. | ||
| Thrift Plan, description | The NuStar Thrift Plan (the Thrift Plan) is a qualified defined contribution plan and participation in the Thrift Plan is voluntary and open to substantially all our employees upon their date of hire. Thrift Plan participants can contribute from 1% up to 30% of their total annual compensation to the Thrift Plan in the form of pre-tax and/or after tax employee contributions. We make matching contributions in an amount equal to 100% of each participant’s employee contributions up to a maximum of 6% of the participant’s total annual compensation. | ||
| Defined Benefit Plan Disclosure [Line Items] | |||
| Defined Benefit Plan, Employer Contributions | $ 15.6 | ||
| Pension Plans (The Pension Plan and Excess Pension Plan) | |||
| Defined Benefit Plan Disclosure [Line Items] | |||
| Defined Benefit Plan Obligation Assumed | $ 22.5 | ||
| Other Postretirement Benefits | |||
| Defined Benefit Plan Disclosure [Line Items] | |||
| Defined Benefit Plan Obligation Assumed | $ 10.2 |