Sales to Related Parties (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Related Party Transaction [Line Items]
Rental income - related parties		$ 234	$ 325	[1]
Other income - related parties		64	26	[1]
MPC
Related Party Transaction [Line Items]
Rental income - related parties		234	325
Other income - related parties		48	10
Product sales to MPC that net to zero		173	223
Other Affiliates [Member]
Related Party Transaction [Line Items]
Other income - related parties		16	16
Product [Member]
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		33	41	[1],[2]
Product [Member] | MPC
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties	[3]	33	41
Service [Member]
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		928	803	[1],[2]
Service [Member] | MPC
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		927	803
Service [Member] | Other Affiliates [Member]
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		$ 1	$ 0

[1] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] There were additional product sales to MPC that net to zero within the consolidated financial statements as the transactions are recorded net due to the terms of the agreements under which such product was sold. For the three months ended March 31, 2020, these sales totaled $173 million. For the three months ended March 31, 2019, these sales totaled $223 million.