Gas Reserves (details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Gas Reserves [Abstract]
Gas Reserves Percent Gas Supplies YTD	6.00%	4.00%
Gas Reserves, Current	$ 18,083	$ 13,140	$ 14,966
Gas Reserves Noncurrent Gross	130,836	81,692	92,179
Gas Reserves Amortization	15,618	5,767	7,486
Total Gas Reserves	133,301	89,065	99,659
Deferred Taxes Related To Gas Reserves	40,553	23,940	28,329
Net Gas Reserves Investment	$ 92,748	$ 65,125	$ 71,330