Consolidated Balance Sheets - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents		$ 15	$ 77
Receivables, net		593	611
Current Assets, Related Parties		656	556
Inventories		110	98
Other current assets		110	98
Total current assets		1,484	1,440
Equity method investments		5,275	4,901
Property, plant and equipment, net		22,145	21,525
Intangibles, net		1,270	1,359
Goodwill		9,536	10,016
Other noncurrent assets		52	60
Total assets		40,430	39,325
Current liabilities:
Accounts payable		242	266
Accrued liabilities		187	272
Accrued property, plant and equipment		283	399
Accrued interest payable		210	184
Operating Lease, Liability, Current		66	0
Other current liabilities		136	645
Total current liabilities		2,132	2,268
Long-term deferred revenue		217	132
Liabilities, Related Parties, Noncurrent		290	46
Long-term debt		19,704	17,922
Deferred income taxes		12	14
Operating Lease, Liability, Noncurrent		302	0
Deferred credits and other liabilities		192	208
Total liabilities		22,849	20,590
Commitments and contingencies (see Note 23)
Series A preferred units		968	1,004
Equity
Total MPLX LP partners’ capital		16,364	17,575
Accumulated other comprehensive loss	[1]	(15)	(16)
Noncontrolling interests		249	156
Total equity		16,613	17,731
Total liabilities, preferred units and equity		40,430	39,325
Operating Lease, Right-of-Use Asset		365	0
Other Assets, Related Parties, Noncurrent		303	24
Current Liabilities, Related Parties		1,008	502
MPC
Current liabilities:
Operating Lease, Liability, Current		1	0
Operating Lease, Liability, Noncurrent		230	0
Equity
Operating Lease, Right-of-Use Asset		232	0
Limited Partners Common Units | Public
Equity
Total MPLX LP partners’ capital		10,800	8,336
Total equity		10,800	8,336
Limited Partners Common Units | MPC
Equity
Total MPLX LP partners’ capital		4,968	(1,612)
Total equity		4,968	(1,612)
Series B Preferred Stock [Member]
Equity
Total MPLX LP partners’ capital		611	0
LOOP and Explorer
Equity
Accumulated other comprehensive loss		(15)	(16)
Retained Earnings [Member] | MPC
Equity
Total equity		$ 0	$ 10,867

[1] These components of “Accumulated other comprehensive loss” are included in the computation of net periodic benefit cost by LOOP and Explorer and are therefore included on the Consolidated Statements of Income under the caption “Income/(loss) from equity method investments.”