Supplemental Gas and Oil Information (Unaudited) Average price per unit (Details)	12 Months Ended
	Dec. 31, 2015 $ / bbl $ / Mcf	Dec. 31, 2014 $ / bbl $ / Mcf	Dec. 31, 2013 $ / bbl $ / Mcf
Natural Gas [Member]
Average Sales Price and Production Costs Per Unit of Production [Line Items]
12 month average first-of the month commodity price | $ / Mcf	2.59	4.35	3.67
Oil [Member]
Average Sales Price and Production Costs Per Unit of Production [Line Items]
12 month average first-of the month commodity price | $ / bbl	50.28	94.99	96.94