Equity Method Investments - Summary of Balance Sheet and Income Statement Data for Equity Method Investments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance Sheets
Outstanding Balance	$ 2,692	$ 2,091
Total Capacity	3,590	2,990
Available Capacity	896	896
Amberjack
Statements of Income
Total revenues	315	204
Total operating expenses	73	47
Operating income	242	157
Net income	243	157
Balance Sheets
Current assets	56	46
Non-current assets	804	846
Total assets	860	892
Current liabilities	4	4
Non-current liabilities	32	4
Equity (Deficit)	824	884
Total liabilities and equity (deficit)	860	892
Mars
Statements of Income
Total revenues	282	241	$ 256
Total operating expenses	104	87	82
Operating income	178	154	174
Net income	179	154	174
Balance Sheets
Current assets	57	53	48
Non-current assets	173	178	187
Total assets	230	231	235
Current liabilities	8	5	5
Non-current liabilities	22	18	0
Equity (Deficit)	200	208	230
Total liabilities and equity (deficit)	230	231	235
Bengal
Statements of Income
Total revenues	77	69	73
Total operating expenses	30	28	28
Operating income	47	41	45
Net income	47	41	45
Balance Sheets
Current assets	35	27	25
Non-current assets	157	156	157
Total assets	192	183	182
Current liabilities	6	9	11
Non-current liabilities	0	0	0
Equity (Deficit)	186	174	171
Total liabilities and equity (deficit)	192	183	182
Explorer
Statements of Income
Total revenues	258
Total operating expenses	115
Operating income	143
Net income	111
Balance Sheets
Current assets	93
Non-current assets	530
Total assets	623
Current liabilities	44
Non-current liabilities	442
Equity (Deficit)	137
Total liabilities and equity (deficit)	623
Colonial
Statements of Income
Total revenues	829
Total operating expenses	449
Operating income	380
Net income	255
Balance Sheets
Current assets	323
Non-current assets	2,920
Total assets	3,243
Current liabilities	519
Non-current liabilities	2,873
Equity (Deficit)	(149)
Total liabilities and equity (deficit)	3,243
Poseidon
Statements of Income
Total revenues	132	116	117
Total operating expenses	35	35	33
Operating income	97	81	84
Net income	87	73	79
Balance Sheets
Current assets	30	19	19
Non-current assets	190	203	218
Total assets	220	222	237
Current liabilities	16	16	18
Non-current liabilities	246	243	237
Equity (Deficit)	(42)	(37)	(18)
Total liabilities and equity (deficit)	220	222	237
Other
Statements of Income
Total revenues	190	152	124
Total operating expenses	108	67	46
Operating income	82	85	78
Net income	73	76	66
Balance Sheets
Current assets	60	50	92
Non-current assets	917	876	625
Total assets	977	926	717
Current liabilities	73	65	99
Non-current liabilities	469	456	245
Equity (Deficit)	435	405	373
Total liabilities and equity (deficit)	977	926	717
May 2018 Acquisition | Amberjack
Statements of Income
Total revenues		295
Total operating expenses		74
Operating income		$ 221
June 2019 Acquisition | Explorer
Statements of Income
Total revenues	443
Total operating expenses	196
Operating income	247
June 2019 Acquisition | Colonial
Statements of Income
Total revenues	1,437
Total operating expenses	735
Operating income	$ 702
October 2017 Acquisitions | Permian Basin
Statements of Income
Total revenues			8
Total operating expenses			5
Operating income			$ 3