Other Assets and Liabilities from Related Parties (Detail) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Other current assets	$ 59	$ 110
Current Assets, Related Parties	591	656
Operating Lease, Right-of-Use Asset	323	365
Other Assets, Related Parties, Noncurrent	675	303
Operating Lease, Liability, Current	65	66
Current Liabilities, Related Parties	364	1,008
Operating Lease, Liability, Noncurrent	258	302
Liabilities, Related Parties, Noncurrent	281	290
MPC
Related Party Transaction [Line Items]
Receivables - related parties	543	621
Prepaid Insurance	11	9
Other current assets	1	0
Sales-type Lease, Interest Income	29	4
Sales-type Lease, Unguaranteed Residual Asset	22	7
Due from Related Parties, Noncurrent	32	21
Operating Lease, Right-of-Use Asset	231	232
Net Investment in Lease, Noncurrent	390	43
Due to Related Parties, Current	247	911
Operating Lease, Liability, Current	1	1
Operating Lease, Liability, Noncurrent	230	230
Other Affiliates [Member]
Related Party Transaction [Line Items]
Receivables - related parties	7	22
Due to Related Parties, Current	42	37
Minimum Committed Volume Contracts [Member] | MPC
Related Party Transaction [Line Items]
Deferred Revenue Related Parties	54	42
Reimbursable Projects [Member] | MPC
Related Party Transaction [Line Items]
Deferred Revenue Related Parties	19	16
Deferred Revenue, Noncurrent, Related Parties	45	53
Other Noncurrent Liabilities [Member] | Other Affiliates [Member]
Related Party Transaction [Line Items]
Deferred Revenue Related Parties	1	1
Other Noncurrent Liabilities [Member] | Other Affiliates [Member]
Related Party Transaction [Line Items]
Deferred Revenue, Noncurrent, Related Parties	$ 6	$ 7