Natural Gas Producing Activities (Unaudited) (Details 2)	12 Months Ended
	Dec. 31, 2011 BillionCubicFootEquivalent MillionsCubicFeet ThousandBarrels well Y	Dec. 31, 2010 BillionCubicFootEquivalent Y	Dec. 31, 2009 BillionCubicFootEquivalent Y
Natural Gas Producing Activities (Unaudited)
Experience of primary Company engineer (in years)	23
Independent audit review percentage of total gas and hydrocarbon reserves	100.00%
Percentage of proved reserves covered by a detail, well by well, independent audit	80.00%
Percentage of properties covered by an independent audit of aggregated groups of wells	20.00%
Maximum number of wells per group in the independent audit of aggregated groups	200
Proved developed reserves:
Equivalent number of million cubic feet of natural gas in each thousand barrels of oil	6
Production Barrels of Oil Equivalents	1
Acquisition of proved developed reserves (Bcfe)	39.7
Actual production (in Bcfe)	198.8	139.0	104.9
Increase in reserves due to extensions, discoveries and other additions (in Bcfe)	694.2	1,893.4	1,158.6
Increase in reserves of natural gas equivalents due to drilling of qualified reserve extensions, discoveries and other additions (in Bcfe)			715
Increase in reserves from offset well drilling (in Bcfe)			400
Upward or (downward) revision in previous natural gas equivalent reserve estimates (in Bcfe)	(388.4)	(603.8)	(94.8)
Change in prior natural gas equivalent reserve estimate due to change in rules (in Bcfe)			55
Price per barrel used in computation of reserves (in dollars per Bbl)	92.84	76.68	58.43
Decrease in natural gas equivalent year end price (in dollars per Dth)			0.06
Maximum period for which reserves are classified as proved undeveloped (in years)	5	5
Term of the Company's drilling plan (in years)			5
Columbia Gas Transmission Corp
Distribution Channel
Prices used in calculation of reserves (in dollars per Dth)	4.198	4.502	4.046
Dominion Transmission, Inc
Distribution Channel
Prices used in calculation of reserves (in dollars per Dth)	4.243	4.563	4.128
East Tennessee Natural Gas Pipeline
Distribution Channel
Prices used in calculation of reserves (in dollars per Dth)	4.159	4.407	3.909
Transcontinental Gas Pipe Line Corp
Distribution Channel
Prices used in calculation of reserves (in dollars per Dth)	4.172	4.422	3.920
Marcellus
Distribution Channel
Prices used in calculation of additional reserves (in dollars per Dth)	1.139
Kentucky
Distribution Channel
Prices used in calculation of additional reserves (in dollars per Dth)	2.149
Natural Gas
Proved developed and undeveloped reserves:
Beginning of year	5,205,692	4,056,059	3,097,260
Revision of previous estimates	(393,129)	(606,308)	(94,728)
Purchase of natural gas in place	39,436	2,536
Sale of natural in place	(1,223)	(1,679)	(741)
Extensions, discoveries and other additions	694,180	1,893,387	1,158,602
Production	(197,570)	(138,303)	(104,334)
End of year	5,347,386	5,205,692	4,056,059
Proved developed reserves:
Beginning of year, proved developed reserves	2,520,569	2,061,353	1,881,767
End of year, proved developed reserves	2,948,546	2,520,569	2,061,353
Oil
Proved developed and undeveloped reserves:
Beginning of year	2,307	2,016	2,125
Revision of previous estimates	781	411	(10)
Purchase of natural gas in place	51
Production	(208)	(120)	(99)
End of year	2,931	2,307	2,016
Proved developed reserves:
Beginning of year, proved developed reserves	2,307	2,016	2,125
End of year, proved developed reserves	2,931	2,307	2,016