Reportable Segments - Schedule of Financial Data for Business Segments and Services (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) segment	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			2
Total Revenues	$ 515	$ 735	$ 1,163	$ 1,530
Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)	177	317	403	695
Operation and maintenance, General and administrative	136	124	262	253
Depreciation and amortization	105	110	209	215
Impairments	0	0	28	0
Taxes other than income tax	17	17	35	35
Operating Income	80	167	226	332
Total assets	12,061		12,061		$ 12,266
Capital expenditures	48	109	102	252
Operating Segments | Gathering and Processing
Segment Reporting Information [Line Items]
Total Revenues	391	587	868	1,217
Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)	176	297	387	657
Operation and maintenance, General and administrative	92	75	173	159
Depreciation and amortization	74	78	148	152
Impairments			28
Taxes other than income tax	11	10	22	21
Operating Income	38	127	110	228
Total assets	9,552		9,552		9,739
Capital expenditures	24	90	58	197
Operating Segments | Transportation and Storage
Segment Reporting Information [Line Items]
Total Revenues	183	252	417	568
Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)	59	123	137	292
Operation and maintenance, General and administrative	45	50	90	95
Depreciation and amortization	31	32	61	63
Impairments			0
Taxes other than income tax	6	7	13	14
Operating Income	42	40	116	104
Total assets	5,662		5,662		5,886
Capital expenditures	24	19	44	55
Eliminations
Segment Reporting Information [Line Items]
Total Revenues	(59)	(104)	(122)	(255)
Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)	(58)	(103)	(121)	(254)
Operation and maintenance, General and administrative	(1)	(1)	(1)	(1)
Depreciation and amortization	0	0	0	0
Impairments			0
Taxes other than income tax	0	0	0	0
Operating Income	0	0	0	0
Total assets	(3,153)		(3,153)		$ (3,359)
Capital expenditures	0	0	0	0
Product
Segment Reporting Information [Line Items]
Total Revenues	196	393	484	836
Product | Operating Segments | Gathering and Processing
Segment Reporting Information [Line Items]
Total Revenues	193	379	468	802
Product | Operating Segments | Transportation and Storage
Segment Reporting Information [Line Items]
Total Revenues	59	114	134	281
Product | Eliminations
Segment Reporting Information [Line Items]
Total Revenues	(56)	(100)	(118)	(247)
Natural Gas, Gathering, Transportation, Marketing and Processing
Segment Reporting Information [Line Items]
Total Revenues	319	342	679	694
Natural Gas, Gathering, Transportation, Marketing and Processing | Operating Segments | Gathering and Processing
Segment Reporting Information [Line Items]
Total Revenues	198	208	400	415
Natural Gas, Gathering, Transportation, Marketing and Processing | Operating Segments | Transportation and Storage
Segment Reporting Information [Line Items]
Total Revenues	124	138	283	287
Natural Gas, Gathering, Transportation, Marketing and Processing | Eliminations
Segment Reporting Information [Line Items]
Total Revenues	$ (3)	$ (4)	$ (4)	$ (8)