Revenues from Contracts with Customers - Disaggregation of Revenue by Identified Revenue Stream (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Total Revenue		$ 809,868	$ 756,608
Natural gas sales
Disaggregation of Revenue [Line Items]
Total Revenue	[1]	572,510	491,248
NGLs sales
Disaggregation of Revenue [Line Items]
Total Revenue	[2]	198,237	202,831
Oil sales
Disaggregation of Revenue [Line Items]
Total Revenue		$ 39,121	$ 62,529

[1] Natural gas sales revenue reported above for first quarter 2019 includes $134.8 million of brokered revenues and $3.0 million of marketing revenue. First quarter 2018 includes $55.9 million of brokered revenues and $3.8 million of marketing revenue.

[2] NGLs sales revenue reported above for the first quarter 2019 includes $424,000 of brokered revenues and first quarter 2018 includes $304,000 of brokered revenues.