Revenue Recognition Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 2,154	$ 2,971	$ 4,840	$ 6,143
Leasing services	299	216	593	434
Derivatives adjustments on commodity sales	64	7	168	30
Other	43	20	65	36
Total other revenues	406	243	826	500
Total revenues	2,560	3,214	5,666	6,643
Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Total revenues	1,565	1,956	3,426	4,148
Products Pipelines
Disaggregation of Revenue [Line Items]
Total revenues	345	442	840	866
Terminals
Disaggregation of Revenue [Line Items]
Total revenues	418	506	859	1,014
CO2
Disaggregation of Revenue [Line Items]
Total revenues	232	310	541	615
Operating Segments | Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,432	1,880	3,127	3,996
Leasing services	114	55	227	110
Derivatives adjustments on commodity sales	(11)	19	41	38
Other	36	14	51	25
Total other revenues	139	88	319	173
Total revenues	1,571	1,968	3,446	4,169
Operating Segments | Products Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	298	397	746	778
Leasing services	42	43	84	84
Derivatives adjustments on commodity sales	0	0	0	0
Other	5	2	10	4
Total other revenues	47	45	94	88
Total revenues	345	442	840	866
Operating Segments | Terminals
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	287	402	600	802
Leasing services	132	105	261	214
Derivatives adjustments on commodity sales	0	0	0	0
Other	0	0	0	0
Total other revenues	132	105	261	214
Total revenues	419	507	861	1,016
Operating Segments | CO2
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	144	306	389	591
Leasing services	11	13	21	26
Derivatives adjustments on commodity sales	75	(12)	127	(9)
Other	2	3	4	7
Total other revenues	88	4	152	24
Total revenues	232	310	541	615
Corporate and eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(7)	(14)	(22)	(24)
Leasing services	0	0	0	0
Derivatives adjustments on commodity sales	0	0	0	1
Other	0	1	0	0
Total other revenues	0	1	0	1
Total revenues	(7)	(13)	(22)	(23)
Firm services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,052	1,251	2,185	2,510
Firm services | Operating Segments | Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	796	889	1,661	1,819
Firm services | Operating Segments | Products Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	67	84	146	164
Firm services | Operating Segments | Terminals
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	189	279	378	529
Firm services | Operating Segments | CO2
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Firm services | Corporate and eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	(1)	0	(2)
Fee-based services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	442	573	1,029	1,163
Fee-based services | Operating Segments | Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	157	187	350	379
Fee-based services | Operating Segments | Products Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	182	252	442	487
Fee-based services | Operating Segments | Terminals
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	95	118	216	266
Fee-based services | Operating Segments | CO2
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	10	15	23	31
Fee-based services | Corporate and eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(2)	1	(2)	0
Total services revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,494	1,824	3,214	3,673
Total services revenues | Operating Segments | Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	953	1,076	2,011	2,198
Total services revenues | Operating Segments | Products Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	249	336	588	651
Total services revenues | Operating Segments | Terminals
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	284	397	594	795
Total services revenues | Operating Segments | CO2
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	10	15	23	31
Total services revenues | Corporate and eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(2)	0	(2)	(2)
Natural gas sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	376	603	875	1,356
Natural gas sales | Operating Segments | Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	377	607	878	1,361
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	0	0	0	1
Natural gas sales | Corporate and eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(1)	(4)	(3)	(6)
Product other than natural gas
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	284	544	751	1,114
Product other than natural gas | Operating Segments | Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	102	197	238	437
Product other than natural gas | Operating Segments | Products Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	49	61	158	127
Product other than natural gas | Operating Segments | Terminals
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3	5	6	7
Product other than natural gas | Operating Segments | CO2
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	134	291	366	559
Product other than natural gas | Corporate and eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(4)	(10)	(17)	(16)
Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	660	1,147	1,626	2,470
Total revenues	723	1,156	1,790	2,505
Commodity sales | Operating Segments | Natural Gas Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	479	804	1,116	1,798
Commodity sales | Operating Segments | Products Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	49	61	158	127
Commodity sales | Operating Segments | Terminals
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3	5	6	7
Commodity sales | Operating Segments | CO2
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	134	291	366	560
Commodity sales | Corporate and eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ (5)	$ (14)	$ (20)	$ (22)