Revenue Recognition - Impact of Adoption (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer									$ 447	$ 469	$ 414
Lease revenue – related parties									56	56
Operations and maintenance – third parties									65	108	104
Costs and Expenses, Related Party									59	54	46
Cost of product sold – third parties									5	7	0
Cost of product sold – related parties									31	25	0
Net income	$ 144	$ 146	$ 119	$ 137	$ 147	$ 155	$ 115	$ 65	546	482	392
Deferred revenue – related party	0				3				0	3
Third Parties | Transportation, Terminaling And Storage Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer									143	209	236
Third Parties | Product Revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer									5	2	0
Related Parties | Transportation, Terminaling And Storage Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer									264	229	178
Related Parties | Product Revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer									35	29	$ 0
Calculated under Revenue Guidance in Effect before Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Lease revenue – related parties									108	107
Operations and maintenance – third parties									64	107
Costs and Expenses, Related Party									58	52
Cost of product sold – third parties									0	6
Cost of product sold – related parties									0	0
Net income									546	487
Calculated under Revenue Guidance in Effect before Topic 606 | Third Parties | Transportation, Terminaling And Storage Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer									142	209
Calculated under Revenue Guidance in Effect before Topic 606 | Third Parties | Product Revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer									0	0
Calculated under Revenue Guidance in Effect before Topic 606 | Related Parties | Transportation, Terminaling And Storage Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer									215	183
Calculated under Revenue Guidance in Effect before Topic 606 | Related Parties | Product Revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer									0	0
Difference between Revenue Guidance in Effect before and after Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue – related party	0				3				0	3
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Lease revenue – related parties									(52)	(51)
Operations and maintenance – third parties									1	1
Costs and Expenses, Related Party									1	2
Cost of product sold – third parties									5	1
Cost of product sold – related parties									31	25
Net income									0	(5)
Deferred revenue – related party	$ 0				$ 0				0	0
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606 | Third Parties | Transportation, Terminaling And Storage Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer									1	0
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606 | Third Parties | Product Revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer									5	2
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606 | Related Parties | Transportation, Terminaling And Storage Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer									49	46
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606 | Related Parties | Product Revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer									$ 35	$ 29