Revenue Recognition Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 2,515	$ 2,953	$ 7,355	$ 9,096
Leasing services	317	226	910	660
Derivatives adjustments on commodity sales	40	21	208	51
Other	47	14	112	50
Total other revenues	404	261	1,230	761
Total revenues	2,919	3,214	8,585	9,857
Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Total revenues	1,803	1,925	5,229	6,073
Products Pipelines
Disaggregation of Revenue [Line Items]
Total revenues	442	484	1,282	1,350
Terminals
Disaggregation of Revenue [Line Items]
Total revenues	423	507	1,282	1,521
CO2
Disaggregation of Revenue [Line Items]
Total revenues	251	298	792	913
Operating Segments | Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,656	1,844	4,783	5,840
Leasing services	119	57	346	167
Derivatives adjustments on commodity sales	(6)	23	35	61
Other	40	10	91	35
Total other revenues	153	90	472	263
Total revenues	1,809	1,934	5,255	6,103
Operating Segments | Products Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	394	438	1,140	1,216
Leasing services	42	45	126	129
Derivatives adjustments on commodity sales	0	0	0	0
Other	6	1	16	5
Total other revenues	48	46	142	134
Total revenues	442	484	1,282	1,350
Operating Segments | Terminals
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	281	397	881	1,199
Leasing services	143	111	404	325
Derivatives adjustments on commodity sales	0	0	0	0
Other	0	0	0	0
Total other revenues	143	111	404	325
Total revenues	424	508	1,285	1,524
Operating Segments | CO2
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	190	283	579	874
Leasing services	13	13	34	39
Derivatives adjustments on commodity sales	46	(1)	173	(10)
Other	2	3	6	10
Total other revenues	61	15	213	39
Total revenues	251	298	792	913
Corporate and eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(6)	(9)	(28)	(33)
Leasing services	0	0	0	0
Derivatives adjustments on commodity sales	0	(1)	0	0
Other	(1)	0	(1)	0
Total other revenues	(1)	(1)	(1)	0
Total revenues	(7)	(10)	(29)	(33)
Firm services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,071	1,227	3,256	3,737
Firm services | Operating Segments | Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	818	882	2,479	2,701
Firm services | Operating Segments | Products Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	69	89	215	253
Firm services | Operating Segments | Terminals
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	185	256	563	785
Firm services | Operating Segments | CO2
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1	1	1	1
Firm services | Corporate and eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(2)	(1)	(2)	(3)
Fee-based services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	503	593	1,532	1,756
Fee-based services | Operating Segments | Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	173	182	523	561
Fee-based services | Operating Segments | Products Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	228	265	670	752
Fee-based services | Operating Segments | Terminals
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	91	132	307	398
Fee-based services | Operating Segments | CO2
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	8	14	31	45
Fee-based services | Corporate and eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3	0	1	0
Total services revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,574	1,820	4,788	5,493
Total services revenues | Operating Segments | Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	991	1,064	3,002	3,262
Total services revenues | Operating Segments | Products Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	297	354	885	1,005
Total services revenues | Operating Segments | Terminals
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	276	388	870	1,183
Total services revenues | Operating Segments | CO2
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	9	15	32	46
Total services revenues | Corporate and eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1	(1)	(1)	(3)
Natural gas sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	506	617	1,381	1,973
Natural gas sales | Operating Segments | Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	507	618	1,385	1,979
Natural gas sales | Operating Segments | Products Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Natural gas sales | Operating Segments | Terminals
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Natural gas sales | Operating Segments | CO2
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1	0	1	1
Natural gas sales | Corporate and eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(2)	(1)	(5)	(7)
Product other than natural gas
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	435	516	1,186	1,630
Product other than natural gas | Operating Segments | Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	158	162	396	599
Product other than natural gas | Operating Segments | Products Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	97	84	255	211
Product other than natural gas | Operating Segments | Terminals
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	5	9	11	16
Product other than natural gas | Operating Segments | CO2
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	180	268	546	827
Product other than natural gas | Corporate and eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(5)	(7)	(22)	(23)
Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	941	1,133	2,567	3,603
Total revenues	982	1,154	2,772	3,659
Commodity sales | Operating Segments | Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	665	780	1,781	2,578
Commodity sales | Operating Segments | Products Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	97	84	255	211
Commodity sales | Operating Segments | Terminals
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	5	9	11	16
Commodity sales | Operating Segments | CO2
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	181	268	547	828
Commodity sales | Corporate and eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ (7)	$ (8)	$ (27)	$ (30)