Disclosure About Oil and Gas Producing Activities (Unaudited) (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Net Cash Flows Abstract
Future Cash Inflows	$ 14,861,131,000	$ 9,380,970,000	$ 22,196,913,000
Future Production Costs	(4,540,209,000)	(3,217,771,000)	(6,113,282,000)
Future Development Costs	(2,014,751,000)	(1,661,394,000)	(4,294,375,000)
Future Income Taxes	(1,897,340,000)	(733,855,000)	(3,340,516,000)
Future Net Cash Flows	6,408,831,000	3,767,950,000	8,448,740,000
Discount at 10%	(3,220,862,000)	(1,873,633,000)	(4,652,684,000)
Standardized measure of discounted future net cash flows	$ 3,187,969,000	$ 1,894,317,000	$ 3,796,056,000