Supplemental Gas Data PV-10 (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]
Revenues	$ 11,303,409	$ 11,837,732	$ 28,502,852
Production costs	5,850,941	6,584,947	10,100,868
Development costs	1,550,294	1,220,010	3,368,621
Income tax expense	1,482,826	1,532,454	5,711,989
Future Net Cash Flows	2,419,348	2,500,321	9,321,374
Discounted to present value at a 10% annual rate	1,464,231	1,481,017	6,337,216
Total standardized measure of discounted net cash flows	$ 955,117	$ 1,019,304	$ 2,984,158	$ 1,680,811