SUPPLEMENTAL INFORMATION - NATURAL GAS AND CRUDE OIL PROPERTIES Capitalized Costs Related to Natural Gas and Crude Oil Producing Activities (Unaudited) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Capitalized Costs Relating to Oil and Gas Producing Activities, by Geographic Area [Line Items]
Proved natural gas and crude oil properties	$ 2,881,189	$ 2,267,165
Unproved natural gas and crude oil properties	60,498	188,206
Uncompleted Wells, Equipment and Facilities	109,385	164,402
Capitalized Costs	3,051,072	2,619,773
Less accumulated DD&A	(1,131,705)	(808,431)
Capitalized Costs, Net	$ 1,919,367	$ 1,811,342