Revenues from Contracts with Customers - Schedule of Revenue Attributable to Identified Revenue Streams is Disaggregated (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Total Revenue	$ 756,608
Natural gas sales
Disaggregation of Revenue [Line Items]
Total Revenue	491,248	[1]
NGLs sales
Disaggregation of Revenue [Line Items]
Total Revenue	202,831	[2]
Oil sales
Disaggregation of Revenue [Line Items]
Total Revenue	$ 62,529

[1] Natural gas sales revenue reported above includes $55.9 million of brokered revenues and $3.8 million of marketing revenue.

[2] NGLs sales revenue reported above includes $304,000 of brokered revenues.