Gas Reserves (details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Gas Reserves [Abstract]
Gas Reserves Percent Gas Supplies YTD	6.00%	3.00%
Gas Reserves, Current	$ 15,324	$ 11,021	$ 14,966
Gas Reserves Noncurrent Gross	126,215	69,097	92,179
Gas Reserves Amortization	12,453	4,071	7,486
Total Gas Reserves	129,086	76,047	99,659
Deferred Taxes Related To Gas Reserves	39,963	26,839	28,329
Net Gas Reserves Investment	$ 89,123	$ 49,208	$ 71,330