Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue
Revenues from contracts with customers	$ 1,019,555	$ 713,837	$ 2,865,104	$ 2,175,389
Income from derivatives and other sources	56,977	(65,957)	228,874	458,459
Total revenue and other	1,076,532	647,880	3,093,978	2,633,848
Natural gas sales
Disaggregation of Revenue
Revenues from contracts with customers	527,122	409,141	1,498,324	1,330,062
Oil sales
Disaggregation of Revenue
Revenues from contracts with customers	59,722	26,527	128,869	79,999
Marketing
Disaggregation of Revenue
Revenues from contracts with customers	89,598	50,767	394,189	166,659
Exploration and production
Disaggregation of Revenue
Total revenue and other	982,131	594,244	2,590,409	2,458,524
Exploration and production | Natural gas sales
Disaggregation of Revenue
Revenues from contracts with customers	527,122	409,141	1,498,324	1,330,062
Exploration and production | Natural gas liquids sales (ethane)
Disaggregation of Revenue
Revenues from contracts with customers	56,185	24,205	115,947	64,078
Exploration and production | Natural gas liquids sales (C3+ NGLs)
Disaggregation of Revenue
Revenues from contracts with customers	282,084	200,328	712,477	525,926
Exploration and production | Oil sales
Disaggregation of Revenue
Revenues from contracts with customers	59,722	26,527	128,869	79,999
Gathering and compression
Disaggregation of Revenue
Total revenue and other	4,441	2,609	12,849	7,472
Gathering and compression | Gathering and compression
Disaggregation of Revenue
Revenues from contracts with customers	4,439	2,609	12,848	7,472
Water handling and treatment
Disaggregation of Revenue
Total revenue and other	404	260	2,450	1,193
Water handling and treatment | Water handling and treatment
Disaggregation of Revenue
Revenues from contracts with customers	405	260	2,450	1,193
Marketing
Disaggregation of Revenue
Total revenue and other	89,556	50,767	488,270	166,659
Marketing | Marketing
Disaggregation of Revenue
Revenues from contracts with customers	$ 89,598	$ 50,767	$ 394,189	$ 166,659