Revenues from Contracts with Customers - Schedule of Revenue Attributable to Identified Revenue Streams is Disaggregated (Detail) - USD ($) $ in Thousands		3 Months Ended	6 Months Ended
		Jun. 30, 2018	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Total Revenue		$ 759,474	$ 1,516,082
Natural gas sales
Disaggregation of Revenue [Line Items]
Total Revenue	[1]	457,706	948,954
NGLs sales
Disaggregation of Revenue [Line Items]
Total Revenue	[2]	225,432	428,263
Oil sales
Disaggregation of Revenue [Line Items]
Total Revenue		$ 76,336	$ 138,865

[1] Natural gas sales revenue reported above for the second quarter includes $93.4 million of brokered revenues and $3.9 million of marketing revenue. The six months includes $149.3 million of brokered revenues and $7.7 million of marketing revenue.

[2] NGLs sales revenue reported above for the second quarter includes $729,000 of brokered revenues and for six months includes $1.0 million of brokered revenues.