Disclosure About Oil and Gas Producing Activities (Unaudited) (Details 3) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Increase (Decrease) in Standardized Measure of Discounted Future Net Cash Flow Relating to Proved Oil and Gas Reserves [Roll Forward]
Standardized Measure, beginning	$ 1,865,649,000	$ 5,233,483,000	$ 3,187,969,000
Net revisions of previous quantity estimates	(9,623,000)	(2,126,998,000)	(603,795,000)
Extensions, discoveries and other changes	209,603,000	15,254,000	1,787,643,000
Sales of reserves in place	0	0	(398,506,000)
Acquistion of reserves	0	0	2,552,491,000
Changes in future development costs	11,556,000	1,618,068,000	(1,013,652,000)
Sales of oil and gas, net of production costs	(454,725,000)	(550,879,000)	(949,389,000)
Net change in prices and production costs	(72,939,000)	(6,996,416,000)	1,010,052,000
Development costs incurred during the period that reduce future development costs	22,523,000	548,112,000	342,987,000
Accretion of discount	186,565,000	709,736,000	413,177,000
Net changes in production rates and other	(67,663,000)	1,551,413,000	(175,419,000)
Net change in income taxes	0	1,863,876,000	(920,075,000)
Aggregrate changes	(174,703,000)	(3,367,834,000)	2,045,514,000
Standardized Measure, ending	$ 1,690,946,000	$ 1,865,649,000	$ 5,233,483,000