Impairments	6 Months Ended
Jun. 30, 2016
Asset Impairment Charges [Text Block]	IMPAIRMENTS SemGas goodwill impairment In March 2016, our SemGas segment revised the volume forecast for its northern Oklahoma system based on revised volume forecasts provided by certain producers who have chosen to adjust plans for production following release of the Oklahoma Corporation Commission’s Regional Earthquake Response Plan that curtails the amount of volume that can be injected into disposal wells. Based on the reduction to our forecast, we tested our SemGas segment's long-lived assets, finite-lived intangible assets and goodwill for impairment at March 31, 2016. No impairment was indicated for SemGas' long-lived assets and finite-lived intangible assets based on an undiscounted cash flow analysis. However, we did record an impairment of SemGas' goodwill for the entire balance of $13.1 million. To test the goodwill for impairment, we used an income approach, supplemented by a market approach to calculate the fair value of the reporting unit. Under the income approach, we utilized a discounted cash flow model to determine the fair value of our SemGas operations. Significant judgments and assumptions included the discount rate, anticipated revenue and volume growth rates, estimated operating expenses and capital expenditures, which were based on our operating and capital budgets as well as our strategic plans. A significant underlying assumption is that commodity prices will eventually improve, water injection issues will be resolved and production volumes will begin to increase. If production does not increase in the future or the production takes longer than anticipated to return, this would negatively affect our key assumptions and potentially lead to finite-lived intangible and long-lived asset impairments in the future. We considered the market approach by comparing the revenue and earnings multiples implied by our income approach to those of comparable companies for reasonableness. Other-than-temporary impairment of equity method investment in NGL Energy During the fourth quarter of 2015, the market price of NGL Energy common units fell below our carrying value per unit and remained below our carrying value as of March 31, 2016. At December 31, 2015, in accordance with ASC 320-10-S99 “Investments - Debt and Equity Securities” we assessed whether such decline in value was other-than-temporary. During this initial assessment, the decrease in value was determined not to be other-than-temporary. The evidence management considered in such assessment included the nature and volatility of such decline, as well as the latest public financial guidance, condition, and results of NGL Energy. Subsequently, we continued to monitor events and developments and, based on NGL Energy's April 21, 2016 announcement of a reduction in its quarterly distribution and lowering of financial performance guidance for the most recent quarter, we concluded that the decline in the value of our investment is other-than-temporary as of March 31, 2016. As such, we recorded an impairment of $39.8 million to our investment in the limited partner units of NGL Energy for the six months ended June 30, 2016. The value of our limited partner investment in NGL Energy was written-down to the market price of $11.04 on December 31, 2015, the date through which we have recorded our equity in earnings as discussed in Note 3. See Note 3 for discussion of the sale of our NGL Energy limited partner units on April 27, 2016. Our investment in the general partner of NGL Energy is not considered to be impaired. There is no readily available market price for our general partner investment as these units are not publicly traded. Based on the relatively low book value of our general partner investment, the value of incentive distribution rights and comparable general partner transactions, we do not believe our investment in the general partner of NGL Energy is impaired.

IMPAIRMENTS

SemGas goodwill impairment

In March 2016, our SemGas segment revised the volume forecast for its northern Oklahoma system based on revised volume forecasts provided by certain producers who have chosen to adjust plans for production following release of the Oklahoma Corporation Commission’s Regional Earthquake Response Plan that curtails the amount of volume that can be injected into disposal wells.

Based on the reduction to our forecast, we tested our SemGas segment's long-lived assets, finite-lived intangible assets and goodwill for impairment at March 31, 2016. No impairment was indicated for SemGas' long-lived assets and finite-lived intangible assets based on an undiscounted cash flow analysis. However, we did record an impairment of SemGas' goodwill for the entire balance of $13.1 million.

To test the goodwill for impairment, we used an income approach, supplemented by a market approach to calculate the fair value of the reporting unit. Under the income approach, we utilized a discounted cash flow model to determine the fair value of our SemGas operations. Significant judgments and assumptions included the discount rate, anticipated revenue and volume growth rates, estimated operating expenses and capital expenditures, which were based on our operating and capital budgets as well as our strategic plans. A significant underlying assumption is that commodity prices will eventually improve, water injection issues will be resolved and production volumes will begin to increase. If production does not increase in the future or the production takes longer than anticipated to return, this would negatively affect our key assumptions and potentially lead to finite-lived intangible and long-lived asset impairments in the future. We considered the market approach by comparing the revenue and earnings multiples implied by our income approach to those of comparable companies for reasonableness.

Other-than-temporary impairment of equity method investment in NGL Energy

During the fourth quarter of 2015, the market price of NGL Energy common units fell below our carrying value per unit and remained below our carrying value as of March 31, 2016. At December 31, 2015, in accordance with ASC 320-10-S99 “Investments - Debt and Equity Securities” we assessed whether such decline in value was other-than-temporary. During this initial assessment, the decrease in value was determined not to be other-than-temporary. The evidence management considered in such assessment included the nature and volatility of such decline, as well as the latest public financial guidance, condition, and results of NGL Energy. Subsequently, we continued to monitor events and developments and, based on NGL Energy's April 21, 2016 announcement of a reduction in its quarterly distribution and lowering of financial performance guidance for the most recent quarter, we concluded that the decline in the value of our investment is other-than-temporary as of March 31, 2016. As such, we recorded an impairment of $39.8 million to our investment in the limited partner units of NGL Energy for the six months ended June 30, 2016. The value of our limited partner investment in NGL Energy was written-down to the market price of $11.04 on December 31, 2015, the date through which we have recorded our equity in earnings as discussed in Note 3. See Note 3 for discussion of the sale of our NGL Energy limited partner units on April 27, 2016.

Our investment in the general partner of NGL Energy is not considered to be impaired. There is no readily available market price for our general partner investment as these units are not publicly traded. Based on the relatively low book value of our general partner investment, the value of incentive distribution rights and comparable general partner transactions, we do not believe our investment in the general partner of NGL Energy is impaired.