Supplemental Gas Data Average Unit Prices (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 MMcf	Dec. 31, 2012 MMcf	Dec. 31, 2011 MMcf
Average Sales Price and Production Costs Per Unit of Production [Line Items]
Oil and Gas Delivery Commitments and Contracts, Remaining Contractual Volume	60.3
Proved Developed and Undeveloped Reserves, Production	172,380,000	156,325,000	153,504,000
Natural Gas, Per Thousand Cubic Feet [Member]
Average Sales Price and Production Costs Per Unit of Production [Line Items]
Average Gas Sales Price before effects of financial settlements	$ 3.85	$ 3.00	$ 4.27
Average effects of financial settlements (per thousand cubic feet)	0.45	1.22	0.63
Average gas sales price including effects of financial settlements (per thousand cubic feet)	$ 4.30	$ 4.22	$ 4.90
Average lifting costs, excluding ad valorem and severance taxes (per thousand cubic feet)	.56	.58	.68