Disclosure About Oil and Gas Producing Activities (Unaudited) (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Net Cash Flows Abstract
Future Cash Inflows	$ 27,331,391	$ 14,861,131	$ 9,380,970
Future Production Costs	(8,627,657)	(4,540,209)	(3,217,771)
Future Development Costs	(3,859,385)	(2,014,751)	(1,661,394)
Future Income Taxes	(3,898,355)	(1,897,340)	(733,855)
Future Net Cash Flows	10,945,994	6,408,831	3,767,950
Discount at 10%	(5,712,511)	(3,220,862)	(1,873,633)
Standardized measure of discounted future net cash flows	$ 5,233,483	$ 3,187,969	$ 1,894,317