SUPPLEMENTAL INFORMATION - NATURAL GAS AND CRUDE OIL PROPERTIES Capitalized Costs Related to Natural Gas and Crude Oil Producing Activities (Unaudited) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Capitalized Costs Relating to Oil and Gas Producing Activities, by Geographic Area [Line Items]
Proved natural gas and crude oil properties	$ 1,781,681	$ 2,075,924
Unproved natural gas and crude oil properties	307,203	319,327
Capitalized Costs, Uncompleted Wells, Equipment and Facilities	51,773	62,392
Capitalized Costs	2,140,657	2,457,643
Less accumulated DD&A	(529,607)	(905,458)
Capitalized Costs, Net	$ 1,611,050	$ 1,552,185