Supplemental Gas Data PV-10 (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]
Revenues	$ 21,602,594	$ 11,777,550	$ 14,804,398
Production costs	(7,105,962)	(4,823,670)	(5,262,635)
Development costs	(3,902,875)	(2,450,589)	(1,674,829)
Income tax expense	(4,025,626)	(1,711,251)	(2,989,435)
Future Net Cash Flows	6,568,131	2,792,040	4,877,499
Discounted to present value at a 10% annual rate	(4,887,320)	(2,055,834)	(3,130,318)
Total standardized measure of discounted net cash flows	$ 1,680,811	$ 736,206	$ 1,747,181