Consolidated Balance Sheets - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents		$ 57	$ 15
Receivables, net		522	593
Current Assets, Related Parties		600	656
Inventories		105	110
Other current assets		45	110
Total current assets		1,329	1,484
Equity method investments		3,992	5,275
Property, plant and equipment, net		21,829	22,145
Intangibles, net		1,055	1,270
Goodwill		7,722	9,536
Operating Lease, Right-of-Use Asset		352	365
Other Assets, Related Parties, Noncurrent		677	303
Other noncurrent assets		50	52
Total assets		37,006	40,430
Current liabilities:
Accounts payable		138	242
Accrued Liabilities, Current		135	187
Current Liabilities, Related Parties		297	1,008
Accrued Property Plant and Equipment Current		234	283
Accrued interest payable		214	210
Operating Lease, Liability, Current		67	66
Other current liabilities		129	136
Total current liabilities		1,214	2,132
Long-term deferred revenue		241	217
Liabilities, Related Parties, Noncurrent		290	290
Long-term debt		20,467	19,704
Deferred income taxes		11	12
Operating Lease, Liability, Noncurrent		284	302
Deferred credits and other liabilities		175	192
Total liabilities		22,682	22,849
Commitments and contingencies (see Note 21)
Series A preferred units		968	968
Equity
Total MPLX LP partners’ capital		13,108	16,364
Accumulated other comprehensive loss	[1]	(16)	(15)
Noncontrolling interests		248	249
Total equity		13,356	16,613
Total liabilities, preferred units and equity		37,006	40,430
MPC
Current assets:
Operating Lease, Right-of-Use Asset		231	232
Current liabilities:
Operating Lease, Liability, Current		1	1
Operating Lease, Liability, Noncurrent		230	230
Series B Preferred Stock [Member]
Equity
Total MPLX LP partners’ capital		601	611
Limited Partners Common Units | Public
Equity
Total MPLX LP partners’ capital		9,509	10,800
Total equity		9,509	10,800
Limited Partners Common Units | MPC
Equity
Total MPLX LP partners’ capital		3,014	4,968
Total equity		3,014	4,968
LOOP and Explorer
Equity
Accumulated other comprehensive loss		(16)	(15)
Retained Earnings [Member] | MPC
Equity
Total equity		$ 0	$ 0

[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.”