Commitments and Contingencies, Capital Commitments (Details) (Capital Commitments, TUCO to Yoakum to Hobbs Plant Transmission Line)	12 Months Ended
Dec. 31, 2014 kV
Capital Commitments \| TUCO to Yoakum to Hobbs Plant Transmission Line
Capital Commitments [Abstract]
Voltage capacity for transmission line (in kV)	345

Capacity for the transmission line under construction.

No definition available.

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