Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2018
Property, Plant and Equipment [Line Items]
Total capitalized interest	$ (73)	$ (49)	$ (84)
Goodwill	110	1,310		$ 1,400
Goodwill Impairment	1,281	0	$ 0
Intangible assets, net	310	$ 0
Amortization expense	30
Stranded tax assets	$ 6
Minimum
Property, Plant and Equipment [Line Items]
Useful lives of gathering facilitates and processing plants (in years)	3 years
Intangible asset, useful life	7 years
Maximum
Property, Plant and Equipment [Line Items]
Useful lives of gathering facilitates and processing plants (in years)	30 years
Intangible asset, useful life	13 years
Pro Forma | ASU 2016-02 | Minimum
Property, Plant and Equipment [Line Items]
Operating lease liability	$ 200
Operating lease, right of use asset	200
Pro Forma | ASU 2016-02 | Maximum
Property, Plant and Equipment [Line Items]
Operating lease liability	350
Operating lease, right of use asset	350
Texas
Property, Plant and Equipment [Line Items]
Goodwill				$ 1,300
Midstream
Property, Plant and Equipment [Line Items]
Goodwill	$ 110