Commitments, Contingencies And Uncertainties (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Loss Contingencies [Line Items]
GHG Emission Level, Percentage	17.00%
Four Corners Coal Plant Participants
Loss Contingencies [Line Items]
Public Utilities, Assessed Coal Severance Surtax Penalty and Interest	$ 30.0
Four Corners Generating Station
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	0.5
Public Utilities, Assessed Coal Severance Surtax Penalty and Interest	1.5
Four Corners Generating Station
Loss Contingencies [Line Items]
Cost of Pollution Control Equipment	$ 39
Four Corners Generating Station
Loss Contingencies [Line Items]
Date participation is ceased	Jul. 06, 2016