Reportable Segments - Schedule of Financial Data for Business Segments and Services (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			2
Total Revenues	$ 596	$ 699	$ 1,759	$ 2,229
Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)	250	263	653	958
Operation and maintenance, General and administrative	124	136	386	389
Depreciation and amortization	105	108	314	323
Impairments of property, plant and equipment and goodwill	0	0	28	0
Taxes other than income tax	17	17	52	52
Operating Income	100	175	326	507
Total assets	11,775		11,775		$ 12,266
Capital expenditures	50	101	152	353
Operating Segments | Gathering and Processing
Segment Reporting Information [Line Items]
Total Revenues	463	542	1,331	1,759
Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)	244	238	631	895
Operation and maintenance, General and administrative	77	79	250	238
Depreciation and amortization	75	77	223	229
Impairments of property, plant and equipment and goodwill			28
Taxes other than income tax	10	10	32	31
Operating Income	57	138	167	366
Total assets	9,525		9,525		9,739
Capital expenditures	21	70	79	267
Operating Segments | Transportation and Storage
Segment Reporting Information [Line Items]
Total Revenues	205	234	622	802
Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)	78	102	215	394
Operation and maintenance, General and administrative	47	57	137	152
Depreciation and amortization	30	31	91	94
Impairments of property, plant and equipment and goodwill			0
Taxes other than income tax	7	7	20	21
Operating Income	43	37	159	141
Total assets	5,524		5,524		5,886
Capital expenditures	29	31	73	86
Eliminations
Segment Reporting Information [Line Items]
Total Revenues	(72)	(77)	(194)	(332)
Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)	(72)	(77)	(193)	(331)
Operation and maintenance, General and administrative	0	0	(1)	(1)
Depreciation and amortization	0	0	0	0
Impairments of property, plant and equipment and goodwill			0
Taxes other than income tax	0	0	0	0
Operating Income	0	0	0	0
Total assets	(3,274)		(3,274)		$ (3,359)
Capital expenditures	0	0	0	0
Product
Segment Reporting Information [Line Items]
Total Revenues	280	320	764	1,156
Product | Operating Segments | Gathering and Processing
Segment Reporting Information [Line Items]
Total Revenues	271	294	739	1,096
Product | Operating Segments | Transportation and Storage
Segment Reporting Information [Line Items]
Total Revenues	79	100	213	381
Product | Eliminations
Segment Reporting Information [Line Items]
Total Revenues	(70)	(74)	(188)	(321)
Natural Gas, Gathering, Transportation, Marketing and Processing
Segment Reporting Information [Line Items]
Total Revenues	316	379	995	1,073
Natural Gas, Gathering, Transportation, Marketing and Processing | Operating Segments | Gathering and Processing
Segment Reporting Information [Line Items]
Total Revenues	192	248	592	663
Natural Gas, Gathering, Transportation, Marketing and Processing | Operating Segments | Transportation and Storage
Segment Reporting Information [Line Items]
Total Revenues	126	134	409	421
Natural Gas, Gathering, Transportation, Marketing and Processing | Eliminations
Segment Reporting Information [Line Items]
Total Revenues	$ (2)	$ (3)	$ (6)	$ (11)