SEGMENTS SEGMENTS (Policies)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Segment Accounting Policy [Text Block]

The accounting policies of the segments are described in Note A. Our chief operating decision-maker reviews the financial performance of each of our three segments, as well as our financial performance as a whole, on a regular basis. Beginning in 2016, adjusted EBITDA by segment is utilized in this evaluation. We believe this financial measure is useful to investors because it and similar measures are used by many companies in our industry as a measurement of financial performance and are commonly employed by financial analysts and others to evaluate our financial performance and to compare financial performance among companies in our industry. Adjusted EBITDA for each segment is defined as net income adjusted for interest expense, depreciation and amortization, noncash impairment charges, income taxes, allowance for equity funds used during construction, noncash compensation, and other noncash items. Prior periods have been adjusted to conform to current presentation. This calculation may not be comparable with similarly titled measures of other companies.