Commitments and Contingencies, Capital Commitments (Details) (Capital Commitments [Member], TUCO to Woodward District Extra High Voltage Interchange [Member])	12 Months Ended
	Dec. 31, 2012 kV
Capital Commitments [Member] | TUCO to Woodward District Extra High Voltage Interchange [Member]
Capital Commitments [Abstract]
Voltage capacity for transmission line (in kV)	345