- Definition

Net quantities of an enterprise's interests in proved developed reserves of either crude oil (including condensate and natural gas liquids), natural gas, synthetic oil and gas, or other nonrenewable natural resource that is intended to be upgraded into synthetic oil and gas as of the beginning and the end of the year. "Net" quantities of reserves include those relating to the enterprise's operating and nonoperating interests in properties. Quantities of reserves relating to royalty interests owned are included in "net" quantities if the necessary information is available to the enterprise. "Net" quantities does not include reserves relating to interests of others in properties owned by the enterprise. The unit of measure for reserve quantities is defined as "barrels" for oil and synthetic oil reserves or "cubic feet" or "cubic meters" for natural gas and synthetic gas reserves.

+ References+ Details

Acquisition and Disposition of Properties (Details) (USD $)	3 Months Ended			6 Months Ended		3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Mar. 31, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Birmingham Metro Operations Center Alabama Gas Corporation	Dec. 31, 2012 Natural Gas Black Warrior Basin Properties Mcf
Gas and Oil Acreage [Line Items]
Proved Developed Reserves (Volume)							97,000,000
Real Estate, Sales Price						$ 14,000,000
Lease back period after sale						18 months
Asset impairment charges	$ 0	$ 0	$ 21,545,000	$ 0	$ 21,545,000
Discount rate	10.00%
Expected time period for future natural gas prices curves to shift lower		5 years