Commitments and Contingencies Commitments and Contingencies, Environmental Contingencies - Unrecorded Unconditional Purchase Obligation (Details) (USD $) In Millions, unless otherwise specified		12 Months Ended	1 Months Ended
	Jun. 30, 2013 Federal Clean Water Act Regulation	Dec. 31, 2013 EPA GHG Regulation	Apr. 30, 2012 Electric Generating Unit Mercury And Air Toxics Standards Rule MW	Dec. 31, 2013 Capital Commitments Industrial Boiler Maximum Achievable Control Technology Rules
Environmental Requirements [Abstract]
Number of potential regulatory options under the proposed Effluent Limitations Guidelines rule	4
Number of issues granted review by the U.S. Supreme Court		1
Generating capacity (in MW)			25
Number of years before affected facilities must demonstrate compliance, low end of range			3 years
Number of years before affected facilities must demonstrate compliance, high end of range			4 years
Liability for estimated cost to comply with regulation				$ 17.2