Property, Plant, and Equipment - Historical Cost Table (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 12,599,722	$ 12,355,671
Less accumulated depreciation	3,685,006	3,290,740
Net property, plant, and equipment	8,914,716	9,064,931
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	9,708	9,495
Gathering Systems – Pipelines [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 5,203,293	5,092,004
Estimated useful life	30 years
Gathering Systems – Compressors [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 2,033,154	1,929,377
Estimated useful life	15 years
Processing Complexes And Treating Facilities [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 3,380,567	3,237,801
Estimated useful life	25 years
Transportation Pipeline And Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 171,069	173,572
Transportation Pipeline And Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	6 years
Transportation Pipeline And Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	45 years
Produced-Water Disposal Systems [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 810,275	754,774
Estimated useful life	20 years
Assets Under Construction [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 289,418	486,584
Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 702,238	$ 672,064
Other [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Other [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	40 years